JPH03213319A - Injection molding method and its device - Google Patents

Abstract

PURPOSE:To make an injection molding device small and upgrade the power of vibration by connecting a vibration generating device on the positions other than the opposite side of a cavity on the upper section or the lower section and the like of a movable mold and/or a fixed side mold, and carrying out molding while the mold is resonated by vibration through a vibration direction conversion body. CONSTITUTION:A movable side mold 2 and a fixed side mold 3 are retained by using a component with possible smallest contact area and retaining a node section of resonance generated by vibration. Then, a vibration generating device 10 supported integrally with a fixing jig 7 is connected with the upper section of a vibration direction conversion body 21 of the movable side mold 2 by means of installation components 11 such as screws or the like. Then, a nozzle 4 of a molding machine 13 is brought into contact with the sprue 3a of the fixed wide mold 3, and a molding material injected into a cavity (a) and molded through said sprue 3a, and supersonic vibration is generated in a vibrator 10 by a supersonic oscillator 12 to resonate the mold 1 by wave length (n). At that time, a loop section of resonance is conformed with the cavity 2a and molding is carried out. The supersonic effect can be utilized effectively to the machine and the flow of the molding material is improved by said arrangement.

Description

[Detailed Description of the Invention] [Published by the Company] The present invention provides for injection molding of a molding material such as a polymeric material.
The present invention relates to an injection molding method and apparatus that can mold a molded product with high physical properties and good appearance.

[Prior Art] Conventionally, injection molding methods have the great advantage of high productivity, and have therefore been widely used for molding products made of thermoplastic resins or materials whose main composition is thermoplastic resins.

However, in recent years, due to advances in research on the physical properties of thermoplastic resins, the rigidity, heat resistance, and chemical resistance of molded products have become more dependent on the material (
It has become known that the molecular weight of the thermoplastic resin (thermoplastic resin) greatly affects the molecular weight.

However, the molecular weight of thermoplastic resins molded using conventional injection molding methods is not so large, and is generally smaller than that of those commercialized as film grades. Therefore, in some cases, the physical properties of molded products such as rigidity, heat resistance, and chemical resistance were poor.Therefore, in order to improve the physical properties, we improved the flow of resin during injection molding. As a result, molding methods that allow the use of resins with high molecular weights constituting molded products have begun to be considered, and several proposals have been made to date. For example, a method of applying ultrasonic vibration to the gate part of a mold, as proposed in Japanese Patent Publication No. 57-2088, or a method of induction heating the mold surface using high frequency, as proposed in Japanese Patent Application Publication No. 61-44616. And so on.

On the other hand, when a polymeric material is used for injection molding, the polymeric material is filled into a mold in a heated state.

For this reason, the molded product thermally expands when heated and contracts when cooled in the mold, resulting in only a molded product smaller than the cavity size of the mold.

Therefore, from the viewpoint of improving the dimensional accuracy of molded products, several proposals have been made to reduce the shrinkage of the material filled in the mold. For example, a method of molding by lowering the temperature of the two materials by significantly increasing the injection pressure and similarly increasing the mold clamping force, or JP-A-58-]
As proposed in No. 14722, the cavity is configured with a horn for ultrasonic vibration, and the material is injected into the cavity and the non-uniformity of the material temperature during the cooling process is attempted to be significantly reduced. Is there a way?

[Problems to be Solved by the Invention] However, the above-mentioned conventional molding method has the following problems.

Namely, Japanese Patent Publication No. 57-2088, Japanese Patent Publication No. 581
The technology proposed in No. 34722 has the problem that the structure of the mold is very complicated, that the ultrasonic vibrations adversely affect the mold itself and other parts of the equipment, and that the material and horn are directly connected. Due to the contact structure, a large load is placed on the horn and the vibration generating part, which poses the problem of not being able to apply sufficient ultrasonic vibration to the material.

Further, as a result of experiments, it has been found that the fluidity of the resin does not improve as expected even when the surface of the mold is heated in the technique proposed in JP-A No. 61-44616.

Furthermore, the method of molding at a low clamping temperature of the material by significantly increasing the injection pressure and similarly high mold clamping force causes distortion in the molded product, making it more likely to deform when used as a product. There was a problem.

Therefore, the present inventors proposed in Japanese Patent Application No. 1-62196 a method and apparatus for injection molding while making the mold resonate, and demonstrated that the above problems could be solved.

However, in the device proposed in Japanese Patent Application No. 1-62196, the ultrasonic vibrator, which is a vibration generator, is coupled to the side opposite to the cavity of the movable mold, so the mold clamping cylinder is extended rearward. As a result, the molding machine became very long and large.

The present invention has been made in view of the above-mentioned circumstances, and the vibration generator is coupled to a position other than the side opposite to the cavity, such as the upper or lower part of the movable mold and/or the fixed mold. The invention of the molding method aims at providing an injection molding method in which the mold is made to resonate by applying vibration from the vibration generator to the mold via a vibration direction converter.

In addition, the invention of the molding device made it possible to downsize the injection molding device, and also made it possible to increase the power of vibration by combining multiple vibration generators with a vibration direction converter and applying vibrations at the same time. The purpose is to provide injection molding equipment.

[Means for Solving the Problem] In order to achieve the above object, the invention of an injection molding method is a method of injection molding a molding material, in which molding is performed while causing a mold to resonate by vibration via a vibration direction converter. This is the method.

A preferable method is to perform molding while causing the mold to resonate using ultrasonic vibrations.

In addition, in order to achieve the above object, the invention of an injection molding device is as follows:
In an apparatus that performs injection molding by supplying molding material from a molding machine to a mold cavity consisting of a movable mold and a fixed mold, the movable mold and the fixed mold are fixed by a fixing jig. In addition, a vibration direction converter is formed in the movable mold and/or the fixed mold, and a vibration generator is coupled to the vibration direction converter.

Preferably, the vibration generator is an ultrasonic vibrator,
The ultrasonic transducer is coupled to any position other than the position opposite to the cavity.

[Example code] Examples of the above solution will be described below.

First, a specific example of an injection molding apparatus will be described based on FIG. 1.

In the figure, 5l is a mold, which is divided into a movable mold 2 and a fixed mold 3, and the movable mold 2 has a vibration direction converter 21 integrally formed therein. The vibration direction converter 21 is a device that changes the direction of vibration transmission to some extent, and the angle thereof can be arbitrarily selected. By using a known L-L converter, L-R converter, L-L-L converter, etc., it is possible to convert the vibration transmission direction by, for example, 90 degrees.

A cavity 2a is provided on the contact surface of the movable mold 2 with the fixed mold 3, and a sprue 3a is provided on the contact surface of the fixed mold 3 corresponding to the cavity 2a.

Metals, ceramics, graphite, etc. can be used for the mold l, but materials with less vibration transmission loss and less fatigue even when the vibration amplitude is increased, such as titanium alloy, phosphorus, etc. It is preferable to use bronze, duralumin, etc.

Furthermore, the surface of the mold 1 may be subjected to treatments such as plating and graining. Further, the mold 1 can be divided into three or more parts, but in this case, it is preferable that the divided screens be located as close to the resonant abdomen as possible in order to improve the transmission of vibrations.

In addition, regarding mold temperature control and molded product ejection methods, please refer to
Although known methods can be used, it is preferable that the joint attached to the mold for introducing or discharging the mold temperature control medium into the mold be installed near the joint. When provided in a mold, it is preferable that the clearance between the ejection bottle and the hole through which it passes is set to a minimum value at the position of the knot in the state before ejection.

4 is a nozzle of the molding machine 13, which injects and supplies molding material to the cavity 2a via the sprue 3a. Sprue 3
The contact surface of a with the nozzle 4 is located approximately at a node (described later) of the ultrasonic vibration (displacement waveform) in the stationary mold 3. C5 is a first holding member (mold clamping member), which is supported by a cylinder 6 so as to be movable forward and backward, and a fixing jig 7 is attached to the tip thereof.

The movable mold 2 is held by the fixing jig 7.
This is achieved by providing a groove 2b on the outer periphery of the groove 2b and abutting a tapered fixing plate 7a on the groove 2b. Therefore, in this case, the movable mold 2 is held by the fixed plate 7a in line contact, and the contact area between the movable mold 2 and the fixed plate 7a becomes extremely small. Thereby, it is possible to minimize the external leakage of the vibrations of the mold 2.

A second holding member 8 is fixed to the outside of the cylinder 6, and a mounting 918a is attached to the tip thereof.

A fixing jig 9 is provided in the mounting 98a in a horizontal direction toward the stationary mold 3, and the tip 9a of this fixing jig 9 is a screw. On the other hand, in the axial direction of the stationary side mold 3, the holding hole 3b is provided up to the position of the resonance node of the stationary side joint fi3 without contacting the side surface of the fixing jig 9. The stationary mold 3 is held by inserting the tip 9a of the fixture 9 into the tip of the holding hole 13.

It is preferable to hold the movable side mold 2 and the stationary side mold 3 by using a holding member having as small a contact area as possible to hold the resonance nodes (described later) due to vibration.

Reference numeral 10 denotes a vibration generator (vibrator) that is integrally supported with the fixing jig 7, and screws and the like are attached to the upper part of the vibration direction converter 21 of the movable mold 2 by means of a member 11. .

As for the vibration, the frequency is IOH, ~10MH.

This can be done by using vibrations. Among these vibrations,
In order to obtain the vibration effect in a short time and to suppress excessive heat generation of the molding material, it is preferable to use ultrasonic waves of 10 KH to 100 KH.

As the vibration generator, devices such as an ultrasonic vibrator, an electrodynamic vibrator, a mechanical vibrator, and a hydraulic vibrator can be used.

Note that the coupling position of the vibration direction converting body 21 to the vibrator 10 can be selected from any position other than the position on the side opposite to the cavity 2a of the movable mold 2. Further, the vibrator 10 can be coupled via a vibration transmitter, and a plurality of vibration transmitters can be installed. In addition, a vibration direction converter is also formed on the fixed side mold,
It is also possible to combine oscillators. Therefore, the vibrator can be coupled to the movable mold and/or the fixed mold via the vibration direction converter.

Reference numeral 12 denotes an ultrasonic oscillator, which generates ultrasonic vibrations in the vibrator lO to excite the movable mold 2 and the fixed mold 3 to resonate.

This resonance frequency is designed and manufactured to a frequency that can be tracked by the ultrasonic oscillator, so the nozzle 4 of the molding machine is pressed against the sprue 38, and the molding material is applied to the sprue 3a.
When supplying power to the cavity 2a via the power source, the system constantly tracks changes in the resonant frequency due to momentary load fluctuations, and also adjusts the required amount of power (
maximum output).

Further, as the vibration mode, in addition to the longitudinal vibration described later, known vibration modes such as two-lateral vibration, torsional vibration, radial vibration, and flexural vibration can be used.

Next, an example of an injection molding method performed using the above injection molding apparatus will be described.

The nozzle 4 of the molding machine 13 is pressed against the sprue 3a of the stationary mold 3, and the molding material is injected into the cavity 2a through the sprue 3a, and the ultrasonic oscillator 1
2, the mold l is made to resonate with n wavelengths by generating ultrasonic vibration (longitudinal vibration) in the vibrator 10. The timing for generating ultrasonic vibrations can be selected depending on the desired effect.

In the first embodiment of the injection molding method, molding is performed by aligning the resonance belly (the part of the displacement waveform farthest apart and the point vibrating most strongly) with the cavity 2a. In this way, the vibration effect of the ultrasonic waves can be utilized to the maximum extent possible, and the flow of the molding material can be improved.

Further, in the second embodiment, the molding is performed by aligning the resonance node (the point where the displacement waveforms intersect and are not vibrating) with the cavity 2a. In this way, the dimensional shrinkage of the molded product is significantly reduced due to the stress effect of the ultrasonic waves.

The vibration frequency when performing the above molding is l as described above.
It is preferable to use a frequency of OKH to 100KH. The larger the amplitude of the ultrasonic vibration, the more effective it will be, but it is preferable to set it according to the material and fatigue strength of the mold.

In order to effectively apply vibration in various vibration modes, the mold 1 is caused to resonate at n wavelengths. In this n-wavelength resonance, n is m/2 (m is a positive integer), but in order to match the resonance to the mold fixing part and the nozzle contact part,
It is preferable that the number of knots is as small as possible, n<3.

In addition, even in the case of n<3, if the resonance abdomen is aligned with the cavity 2a and the vibration effect of the ultrasonic wave is made to resonate to the maximum extent possible, the flow of the molding material will be good as described above. Become.

When carrying out the above-mentioned first and second embodiments, the positions where the movable mold 2 and the fixed mold 3 are held by the fixing jigs 7 and 9, respectively, are made to coincide with the nodes of resonance caused by ultrasonic waves. If molding is performed while causing resonance, transmission of vibration to the outside can be effectively prevented.

Molding materials that can be molded by the above-mentioned injection molding method and apparatus include organic materials such as plastics, rubber, and elastomers, inorganic materials such as inorganic polymers, ceramics, metals, and glass, other foods, and mixed materials thereof. Examples include materials that have some fluidity during molding.

Examples of plastics include the following thermoplastic resins: α-olefin resins (polyethylene, polypropylene, polystyrene, Synthiotactic W polystyrene, reinforced vinyl resin, polybutene, ultra-high molecular weight Polyethylene, polymethylpentene, ionomer, polybutylene, etc.) Polyester resin (polyethylene terephthalate, polyethylene terephthalate, polyarylate, etc.) Polyether resin 11fI (polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, polyester resin) Allyl sulfone, polyoxybensylene, polyphenylene oxide, polycyanoallyl ether [JP-A-52-223226], etc.) Polycarbonate resin Polyimide resin Polyamide resin Polyamideimide resin Methacrylic resin Fluorine resin MBS (Methacrylate Phtadiene Styrene) resin AAS (acrylate acrylonitrile styrene)
Resin AS (acrylonitrile styrene) Resin ACS (chlorinated acrylonitrile polyethylene styrene) Resin ABS (acrylonitrile butadiene styrene)
ResinsPolyacetal resinsCellulose resinsPolyvinylidene chlorideChlorinated polyethyleneEVA (ethylene vinyl acetate) resinsPolyurethane resinsSilicone resinsAllyl resinsFuran resinsLiquid crystal polymersEpoxy resins as thermosetting resinsPhenol resinsPolybutadiene resinsSilicone resinsUnsaturated polyesters Resin amino resin etc.

As a thermoplastic elastomer Styrene-butadiene elastomer polyester elastomer Polyethylene elastomer Urethane elastomer Vinyl chloride elastomer, etc.

Furthermore, injection molding in the present invention includes multicolor molding, insert molding, outsert molding, injection compression molding, injection foam molding9 reaction injection molding, mixed color injection molding, etc.
This includes all molding methods in which a molding material in a fluid or rubber-like state is press-fitted into a mold, shaped into a predetermined shape, and then the molded product is taken out.

``ψachika'' Hereinafter, the injection molding method of the embodiment of the present invention and the experimental results conducted using the apparatus will be explained while comparing with a comparative example.

Experimental Example 1 Injection molding apparatus: The apparatus shown in FIG. 1 Injection molding was performed under the above conditions while the mold was resonated, and the flow length at that time was determined.

Flow length is measured by measuring the length of resin flowing into the cavity.
The evaluation was based on the average value of 0 times.

The results are shown in Table 1.

The experiment was conducted under the same conditions as Experimental Example 1, except that the mold was not caused to resonate by ultrasonic waves.

An experiment was conducted under the same conditions as Comparative Example 1 by heating the mold to 200° C. using a far-infrared heater. This example is considered to be equivalent to the conventional example in which molding is performed by raising the mold surface temperature using a high-frequency induction heating device.

Comparative Example 3 As shown in FIG. 7, an experiment was conducted under the same conditions as Experimental Example 1, except that the vibrator 10 was positioned at the contact portion between the movable mold 2 and the fixed mold 3. At this time, the mold was not in a resonant state.

Table 1 shows the results of Comparative Examples 1 to 3.

[Margins below] Table 1) () is the standard deviation As a result, according to the present invention, not only when no ultrasonic waves are applied, but also when ultrasonic waves are simply applied or when the mold is heated, It was found that the fluidity of the molding material was much improved.

Experimental Example 2 Injection molding apparatus: Same as the apparatus shown in FIG. 1 except that the fixed mold and the movable mold were slightly longer.

Molding material: Polypropylene (J-7000, manufactured by Idemitsu Petrochemical Co., Ltd.) Injection molding was performed under the above conditions while making the mold resonate, and the diameter of the molded product was measured.

Evaluation was performed using the average value of 10 molded products.

The results are shown in Table 2.

Comparative Example 4 An experiment was conducted under the same conditions as Experimental Example 2, except that the mold was not caused to resonate by ultrasonic waves.

An experiment was conducted under the same conditions as in Experimental Example 2, except that the vibrator 10 was positioned at the contact portion between the movable mold 2 and the fixed mold 3 (see FIG. 7).

LL kk Isa A eHa frog eyes? As a result, according to the present invention, not only when no ultrasound is applied, but also when compared with the case where ultrasound is simply applied,
It has been found that a molded product with significantly small dimensional shrinkage can be obtained.

Experimental Example 3 The load current of the ultrasonic oscillator was measured when molding was performed in Experimental Example 1 while holding the mold in a line contact state.

The results are shown in Table 3.

Experimental Example 4 The mold was held using a fixing plate whose tip was not tapered. In this case, the fixing plate is in surface contact with the mold.

Table 3 In Experimental Example 4 (surface contact) where the load current was high, it was clearly found that vibrations were flowing out through the fixed plate.

As a result, it was found that holding the mold by line contact is very effective.

Experimental Example 5 Injection molding apparatus: The apparatus shown in FIG. 1 Molding material: 30% by weight of talc Contained under the same conditions as for polypropylene, molding was carried out under the same conditions as described above while causing the resonator of the mold to resonate.

The indentation (x m m ) of the weld portion at the location where the welt line occurred as shown in FIG. 6(b) was determined.

The results are shown in Table 4.

Comparative Example 6 Molding was carried out under the same conditions as Experimental Example 5 except that the ultrasonic oscillation was stopped.

The results are shown in Table 4.

Table 4 [Effects of the Invention] As described above, according to the invention of the injection molding method, vibrations can be efficiently transmitted by causing the mold to resonate with the vibrations.

In addition, it maximizes the vibration effect and improves the fluidity of the molding material, making it possible to mold composite materials containing large amounts of high-molecular weight plastics and fillers, which were difficult with conventional molding techniques, and in low-temperature ranges. This makes molding easier and reduces weld marks on the molded product.

Furthermore, by making the mold resonate, vibration can be transmitted more efficiently and the stress effect of vibration can be utilized, which is better than simply applying vibration to the mold.

Dimensional shrinkage of molded products can be significantly reduced.

According to the invention of the injection molding device, it is possible to improve the fluidity of the molding material, and it is possible to mold products with excellent physical properties and dimensional accuracy, and it is also possible to minimize the outflow of vibrations from resonant parts. This has the effect of not adversely affecting other parts of the device.

Moreover, the injection molding apparatus can be downsized, and the vibration power can be increased by using a plurality of vibration generators.

[Brief explanation of drawings]

Figure 1 is a cutaway side view of the main parts of the injection molding apparatus used in Experimental Example 1, Figure 2 is a plan view of the cavity used in Experimental Example 1,
Figure 3 is an explanatory diagram of the displacement waveform and wavelength when the mold resonates, Figure 4 is an explanatory diagram of the cavity used in the molding experiment of Experimental Example 2, and Figure 5 is an explanatory diagram of the resonance conditions in the molding experiment of Experimental Example 2. Explanatory diagram. FIG. 6(a) is an explanatory diagram of the cavity used in the experiment of Experimental Example 5, FIG. 6(b) is an explanatory diagram of the weld part dent, and FIG. 7 is a schematic diagram of the apparatus side used in Comparative Examples 3 and 5. shows. l: Mold 2: Movable side mold 21: Vibration direction converter 2a: Cavity 2b: Groove 3: Fixed side mold 3a Varnish blue 3b: Holding hole 7.9: Fixing jig 10: Vibrator

Claims (2)

[Claims] (1) An injection molding method for injection molding a molding material, characterized in that molding is performed while causing a mold to resonate by vibration via a vibration direction converter. (2) The injection molding method according to claim 1, wherein the vibration is ultrasonic vibration. (3) In a device that performs injection molding by supplying molding material from a molding machine to the cavity of a mold consisting of a movable mold and a fixed mold, the movable mold and the fixed mold are held in a fixing jig. An injection molding apparatus characterized in that a vibration converter is formed in the movable mold and/or the fixed mold, and a vibration generator is coupled to the vibration converter.