JP2002370255A - Injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize high speed filling in injection molding to enhance the quality of a product while reducing output necessary for high speed filling. SOLUTION: When the molten material P in the inner peripheral space 1a of the leading end of a heating cylinder 1 is injected by rapidly advancing a screw 2, the ultrasonic oscillator main body 41 of an ultrasonic oscillator 4 is excited to propagate ultrasonic vibration to the wall surface in the vicinity of an injection nozzle 11 through a horn 42 to excite the molten material P flowing toward a mold 3 along the inner periphery of the nozzle. By this constitution, the friction force of the injection nozzle 11 with the inner wall of the heating cylinder 1 in the vicinity thereof is reduced and the internal friction of the molten material P is also reduced and, therefore, the molten material P is enhanced in its apparent flowability to be injected in the mold 3 at a high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding machine for injection-molding a molten material into a mold in an injection molding technique, and more particularly to an injection molding machine for realizing high-speed filling of a material.

[0002]

2. Description of the Related Art FIG. 2 is a partial sectional view showing a conventional injection molding machine together with a part of a mold. As shown in FIG. 2, this type of injection molding machine has a
Nozzle 102 that can be in close contact with sprue 104a of No. 4
And a screw 103 disposed inside the heating cylinder 101 so as to be rotatable around the axis and movable in the axial direction.

That is, in an injection molding machine, a molding resin material in the form of a pellet filled from a material charging port (not shown) located on the right side of the figure is rotated by a screw 103 so that the resin in the heating cylinder 101 is removed. It is sent to the space 101a on the tip side of the screw 103 while being measured, and is heated and melted and kneaded in the process. Next, the molten material P is injected and filled into the mold 104 from the injection nozzle 102 by the screw 103 having receded to the right side in the drawing in the above-described measuring process and advancing to the left side in the drawing. It cures and becomes a product.

In injection molding, a mold 10 is used.
It is known that the injection filling of the molten material P into the mold 4 at a high speed and that the filling of the mold 104 is completed before the molten material P changes in viscosity contribute to the improvement of product quality. I have. In recent years, a high-speed filling molding machine has been developed for this purpose, and a high-output driving device for driving the screw 103 with high speed and high responsiveness has also been developed.
However, although the technology of the driving device required for high-speed molding is advanced, it cannot be said that the molding technology focusing on the movement of the material is sufficiently advanced.

For example, a molten material P made of a synthetic resin is
When pressurized, it is elastically deformed, though not as much as rubber material.
Also, at the time of injection, the molten material P and the heating cylinder 101
The frictional force with the inner wall of the injection nozzle 102, particularly the frictional force with the inner wall of the injection nozzle 102, and the molecular frictional force inside the material increase, so that even if the screw 103 is advanced at a high speed, the molten material P cannot follow the movement with good response. . For this reason, as the screw 103 moves forward, the molten material P is first compressed and then starts to move toward the mold 104, and eventually the flow rate of the molten material P in the mold 104 Is screw 1
It is only about 1/10 of the moving speed of 03.

In the heating cylinder 101, the molten material P
Is compressed, a load is applied to the screw 103 by the reaction force, so that the molding pressure increases. In addition, the higher the injection speed, the greater the effect. Therefore, it is necessary to further increase the output of the driving device for driving the screw 103, and also increase the rigidity of the driving device to withstand the load. There is a need.

If the output of the driving device for operating the screw 103 is increased, the injection speed of the molten material P into the mold 104 can be increased, but the molten material P is filled at the speed viewed from the injection molding machine side. Not necessarily. That is, after the screw 103 is moved forward, the heating cylinder 10
Until the molten material P starts moving from inside 1 toward the mold 103, a time delay occurs due to the above-described generation and compression of friction, and as a result, only about 1/10 of the target speed can be realized. This means that the energy loss is large, and that it is not possible to satisfy the demand for completing the filling in a shorter time and further improving the product quality.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and its technical problem is to improve the product quality by realizing high-speed filling in injection molding. It is to plan.

Another technical problem to be solved by the present invention is to reduce energy consumption by reducing the output required for high-speed filling, or to reduce the size of the apparatus.

[0010]

Means for Solving the Problems As means for effectively solving the above-mentioned technical problems, an injection molding machine according to the present invention is characterized in that a heating cylinder is injected into a mold from the heating cylinder. An ultrasonic oscillator for vibrating the molten material is attached.

According to a second aspect of the present invention, in the injection molding machine according to the first aspect, the ultrasonic oscillation device includes a horn for propagating the excited ultrasonic vibration, and the horn is provided with a heating horn. This is in contact with the injection nozzle of the cylinder or its vicinity.

According to a third aspect of the present invention, in the injection molding machine according to the first aspect of the present invention, the driving of the ultrasonic oscillation device is controlled so as to be synchronized with the injection operation by advancing the screw. is there.

[0013]

FIG. 1 is a partial sectional view schematically showing a preferred embodiment of an injection molding machine according to the present invention together with a part of a mold. In this figure, reference numeral 1 denotes a heating cylinder, 2 denotes a screw disposed inside the heating cylinder 1 so as to be rotatable around an axis and to be movable in an axial direction (left-right direction in the drawing), and 3 denotes a mold. A sprue 32 serving as a material supply port to a molding space (cavity) 31 of the mold 3 is provided at the tip of the heating cylinder 1 facing left in the drawing.
An injection nozzle 11 capable of closely contacting with the nozzle is formed.

A hopper-shaped material input port (not shown) is provided on the right side of the heating cylinder 1 in the drawing, and pellet-shaped synthetic resin material for molding is injected into the heating cylinder 1 from this material input port. Is done. Further, a heater (not shown) for heating and melting the injected pellet-shaped synthetic resin material is wound around the outer periphery of the heating cylinder 1.

That is, the heating cylinder 1
The synthetic resin material in the form of pellets fed into the inside is sent to the inner peripheral space 1a in the tip of the heating cylinder 1 by the rotation of the screw 2, and is kneaded while being melted by the heat of the heater in the process. Become. In addition, as the molten material P is sent to and stored in the inner circumferential space 1a of the tip of the heating cylinder 1, the screw 2
While rotating, it is moved backward to the right in the figure. Then, by setting the retraction stroke at this time, the molten material P injected into the mold 3 in one shot (one injection molding) is set.
Is properly weighed.

An ultrasonic oscillator 4 is mounted near the injection nozzle 11 in the heating cylinder 1. The ultrasonic oscillator 4 includes an ultrasonic oscillator main body 41 and a horn 42 connected to the ultrasonic oscillator main body 41 and having a tip abutting on a part of an outer peripheral surface near a tip of the heating cylinder 1. , And is fixed to the heating cylinder 1 via the pedestal 43. Therefore, the ultrasonic oscillator 4
Is integrated with the heating cylinder 1 and the heating cylinder 1
The horn 42 is always in contact with the heating cylinder 1 at the same position even if the horn moves forward or backward toward the mold 3.

The ultrasonic oscillator main body 41 includes an oscillator selected from, for example, a piezoelectric ceramic oscillator, a Langevin type oscillator, a magnetostrictive oscillator, and the like.
The high-frequency oscillation voltage supplied from the high-frequency oscillation circuit 44 is converted into ultrasonic vibration. Note that, as is well known, an ultrasonic wave is a sound wave having a frequency exceeding an audio frequency range and generally means a sound wave of 20 kHz or more.

The horn 42 is made of metal,
The ultrasonic vibration excited by the ultrasonic oscillation device main body 41 is amplified to a required amplitude and propagated to the injection nozzle 11 of the heating cylinder 1 and its vicinity. That is, the horn 42 resonates by the excitation of the ultrasonic oscillation device main body 41, repeats expansion and contraction at the frequency of the ultrasonic wave, and excites the molten material P via the injection nozzle 11 and the wall surface in the vicinity thereof. .

A high-frequency oscillation circuit 44 for applying an excitation voltage to the ultrasonic oscillation device main body 41 operates at a timing when the screw 2 is moved forward from the metering operation completion position toward the left side in the figure, that is, in the heating cylinder 1. Is driven in synchronization with the operation timing when the molten material P is injected and filled into the mold 3, and is controlled to stop when the filling of the molten material P into the mold 3 is completed.

According to the injection molding machine of the present embodiment having the above-described configuration, as described above, first, the synthetic resin pellets introduced from the material inlet are rotated by the rotation of the screw 2 so that the synthetic resin pellets in the heating cylinder 1 are in the front end. Sent to the surrounding space 1a,
In the process, the mixture is kneaded while being melted by the heat of the heater, and becomes a molten material P. In addition, the screw 2 is moved toward the right side in the drawing, and stops rotating by a signal from a sensor that detects this at the time when the screw 2 reaches a preset weighing completion position. Of the molten material P having the filling amount of?

Next, the tip of the injection nozzle 11 of the heating cylinder 1 is brought into close contact with the sprue 32 of the mold 3 by moving the injection molding machine toward the left side in the figure. The molten material P in the inner peripheral space 1a of the tip end of the heating cylinder 1 is rapidly moved from the injection nozzle 11 to the molding space of the mold 3 by rapidly advancing the screw 2 at the measurement completion position in the inside toward the left side in the figure. 31 is injected and filled. The molten material P filled in the molding space 31
Is cross-linked and hardened here to be a synthetic resin product having a shape corresponding to the molding space 31.

By rapidly advancing the screw 2 to the left side in the figure, the high-frequency oscillation circuit 44 is simultaneously driven when the molten material P in the inner peripheral space 1a of the heating cylinder 1 is injected. A high-frequency excitation voltage is applied to the ultrasonic oscillation device main body 41 of the ultrasonic oscillation device 4. The ultrasonic vibration generated by the excitation of the ultrasonic oscillation device main body 41 is amplified to a required amplitude via a horn 42, propagated to the wall surface near the injection nozzle 11 in the heating cylinder 1, and The molten material P injected toward the mold 3 is vibrated.

When the ultrasonic vibration is applied to the molten material P, the molten material P makes intermittent contact with the injection nozzle 11 and the inner wall of the heating cylinder 1 in the vicinity thereof.
The frictional force between the heating cylinder 1 and the injection nozzle 11 is reduced. The ultrasonic vibration incident on the molten material P is
The part is reflected at the interface between the injection nozzle 11 and the heating cylinder 1 in the vicinity of the injection nozzle 11 and interferes with the incident wave to become a standing wave. In a portion that becomes a “node” of such a standing wave,
The molten material P is repeatedly expanded and contracted every half cycle of the vibration, and the molten material P is agitated because the displacement is large in the "antinode" portion. Therefore, by such an action,
The internal friction of the molten material P is also reduced, and the apparent fluidity is increased.

For this reason, the molten material P in the inner circumferential space 1a of the tip of the heating cylinder 1 is injected into the mold 3 at a high speed, responding to the high-speed advance of the screw 2 with good response. Therefore, the filling of the molten material P is performed in a short time, and the filling is completed before the viscosity of the molten material P changes, so that the occurrence of uneven viscosity in the mold 3 is suppressed and the product quality is improved. be able to.

Further, as a result of the apparent fluidity of the molten material P being increased, the molten material P is less likely to be compressed in the inner peripheral space 1a of the heating cylinder 1, so that the injection pressure is reduced.
For this reason, the output of the drive device for making the screw 2 move forward can be reduced. In addition, since the injection pressure required for high-speed filling is reduced, it is not necessary to increase the rigidity of the device, so that a smaller output and a smaller size can be achieved. Therefore, it is possible to reduce the equipment cost, the amount of electric power, and the installation space.

Further, since the molten material P is well stirred and mixed by the application of the ultrasonic wave, the degree of kneading is improved, and the molten material P is filled into the molding space 31 of the mold 3 in a short time. As described above, uneven viscosity is less likely to occur. For this reason, the pressure in the molding space 31 is made uniform, and the dimensional accuracy of the product is improved. Further, it is difficult to generate a weld defect that is unfavorable in mechanical strength and aesthetic appearance of the product, thereby improving the quality of the product. Can be.

When the filling of the molten material P into the mold 3 is completed, the driving of the high-frequency oscillation circuit 44 is stopped, and the ultrasonic oscillation operation of the ultrasonic oscillation device main body 41 is also stopped. Thereafter, the injection molding machine is separated from the mold 3, the mold 3 is opened, and the product is taken out.

[0028]

According to the injection molding machine according to the first aspect of the present invention, when the molten material is injected into the mold from the heating cylinder by the ultrasonic oscillation device attached to the injection nozzle of the heating cylinder or the vicinity thereof. The vibrator is configured to vibrate the molten material to reduce the frictional force between the molten material flowing toward the mold and the inner walls of the heating cylinder and the injection nozzle, and reduce the internal friction of the molten material. .
For this reason, the apparent fluidity of the molten material increases,
High-speed filling can be achieved, and as a result, the homogeneity of the molten material and the uniformity of the pressure inside the mold improve the product dimensional accuracy, and improve the mechanical strength of the molded product, thereby improving the quality of the product. Improvement can be achieved.

In addition, since the apparent fluidity of the molten material is increased, the injection pressure at the time of high-speed filling is reduced, so that it is not necessary to increase the output and rigidity of the apparatus, thereby reducing power consumption. In addition, space can be saved.

According to the injection molding machine of the second aspect of the present invention, since the ultrasonic vibration is propagated to or near the front end of the heating cylinder via the horn, the ultrasonic vibration is directed from the inner peripheral space into the mold. The injected molten material can be efficiently vibrated.

According to the injection molding machine of the third aspect of the present invention, the driving of the ultrasonic oscillator is controlled so as to be synchronized with the injection operation by the advancement of the screw, so that the molten material can be efficiently produced only at the time of injection. By vibrating, the effect of the first aspect of the invention can be reliably realized.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view schematically showing a preferred embodiment of an injection molding machine according to the present invention together with a part of a mold.

FIG. 2 is a partial cross-sectional view schematically showing an injection molding machine according to a conventional technique together with a part of a mold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating cylinder 1a Inner end space 11 Injection nozzle 2 Screw 3 Mold 31 Molding space 32 Sprue 4 Ultrasonic oscillator 41 Ultrasonic oscillator main body 42 Horn 43 Mount 44 High frequency oscillator circuit P Melted material

Claims (3)

[Claims] 1. A molten material (P) injected into a mold (3) from a heating cylinder (1) by a heating cylinder (1).
An injection molding machine characterized by having an ultrasonic oscillator (4) for applying vibration. 2. An ultrasonic oscillator (4) comprising a horn (42) for transmitting excited ultrasonic vibrations, the horn (42) being an injection nozzle (11) of a heating cylinder (1).
The injection molding machine according to claim 1, wherein the injection molding machine is in contact with the vicinity of the injection molding machine. 3. The injection molding machine according to claim 1, wherein the driving of the ultrasonic oscillator (4) is controlled so as to be synchronized with the injection operation by the advancement of the screw (2).