JP3562567B2 - Ultrasonic injection mold - Google Patents

Description

【００３５】
表１から明らかなように、切り込み２０を形成し、超音波振動子７から複合振動を発生させた実施例１で最も良好な結果が得られた。なお、比較例２に示すように、複合振動を与えただけでも、Ｄ＝０．５λ〜０．６λの範囲内でも転写率の向上が認められた。
【００３６】
実施例１におけるキャビティ６の振動状態を図５のグラフに、比較例２におけるキャビティ面の振動状態を図６のグラフに示す
図５のグラフからわかるように、実施例１の場合には、キャビティ６のほぼ全体にわたって、ほぼ均一に十分な振幅を得ることができた。
図６のグラフからわかるように、切り込みを形成しない場合は、振幅はキャビティの全体にわたってばらついている。キャビティの中央では高い振幅が得られるが、キャビティの周縁近傍では振幅が小さくなり、その部分では十分な振幅が得られていない。
【００３７】
【発明の効果】
本発明によれば、既存の金型に簡単な改良を施すだけ転写性が高く、収縮率及び複屈折の低い品質の優れた成形品を得ることが可能になる。
特に、特開平１０−６６１号公報に記載の射出成形方法においても、相当直径Ｄが０．５λ〜０．６λの範囲内で及び０．６λ以上の範囲で成形品の品質を向上させることが可能になるので、大型の金型で大型の成形品を射出成形することが可能になる。
【図面の簡単な説明】
【図１】本発明の一実施形態にかかる超音波射出成形用金型の概略を示す一部を断面した側面図である。
【図２】金型に形成する切り欠きの一実施形態を示す斜視図である。
【図３】スリットの配置例を示す金型の平面図で、図３（ａ）は、単一のスリットがキャビティと同心に形成された例を示し、図３（ｂ）は、二つのスリット２０がキャビティと同心円状に形成された例を示す。
【図４】実施例における表１との関係で、成形品の転写率を説明するための図である。
【図５】実施例１におけるキャビティの表面の振動状態を示すグラフである。
【図６】比較例２におけるキャビティの表面の振動状態を示すグラフである。
【符号の説明】
１ ノズル
２ 固定金型固定板
２′ 固定金型保持部材
３ 固定金型
４ 可動金型
５ スプルー
６ キャビティ
７ 超音波振動子
８ 振動方向変換体
１０ 可動金型固定板
１０′ 可動金型保持部材
１１ 油圧シリンダ
１２ 突出しピン
２０ 切り欠き[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mold for ultrasonic injection molding, and more particularly to a mold for ultrasonic injection molding that has excellent transferability and can effectively prevent the occurrence of birefringence and warpage.
[0002]
[Prior art]
Conventionally, in the injection molding of a molding material such as a resin, there has been known a method of performing injection molding while applying ultrasonic vibration to the molding material at the time of injection molding in order to obtain an injection molded product having high transferability and low shrinkage. ing.
For example, Japanese Patent Publication No. 57-2088 discloses an injection molding method in which a conical horn is attached to a mold gate for connecting a cavity and a runner in a communicating manner, and vibration is applied from the horn to a molding material in the gate. Is disclosed.
Further, Japanese Patent Application Laid-Open No. 58-134722 discloses a method of performing injection molding using a mold having a cavity formed in a horn of an ultrasonic vibrator.
Further, Japanese Patent Application Laid-Open No. 61-270131 discloses a method of performing injection molding with a mold having an ultrasonic vibration device incorporated in a cavity.
[0003]
However, in the conventional ultrasonic molding method described above, the ultrasonic waves must be locally applied to the mold in order to efficiently apply the ultrasonic waves, which is not suitable for large molded products and the structure of the mold is complicated. Was a problem.
In order to solve such a problem, the present applicant disclosed in Japanese Patent Application Laid-Open No. 10-661 that injection molding is performed in which the equivalent diameter D of a mold is set to less than 0.6 times the wavelength λ at the time of one-wave resonance of ultrasonic vibration. A method has been disclosed. According to this method, the optimal equivalent diameter D of the mold can be selected according to the frequency of the ultrasonic wave oscillated from the ultrasonic vibrator, and high transfer can be achieved even if the molded article to be injection-molded becomes large. There is a characteristic that the property and the low shrinkage can be maintained.
[0004]
By the way, the demand for precision injection molding in recent years has been increasing, and injection molding with higher transferability, lower shrinkage ratio and lower birefringence has been demanded.
However, in the injection molding method described in Japanese Patent Application Laid-Open No. 10-661, although the above requirement can be satisfied with a mold having an equivalent diameter D of 0.5λ or less, within a range of 0.5λ to 0.6λ, There was a problem that transferability, shrinkage and birefringence were slightly inferior, and a sufficiently satisfactory molded product could not be obtained.
When the equivalent diameter D is 0.6λ or more, transferability, shrinkage and birefringence are inferior, and there is a problem that a satisfactory molded product cannot be obtained.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and it is possible to further improve the high transferability, the low shrinkage, and the low birefringence only by making a simple improvement to the mold. In the injection molding method described in JP-A-661, even when a large molded product having an equivalent diameter D exceeding 0.5λ is injection-molded, a molded product excellent in high transferability, low shrinkage, and low birefringence is obtained. It is an object of the present invention to provide a mold for ultrasonic injection molding which can be performed.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the present inventor conducted experiments with variously changed mold shapes. As a result, the present inventor has found that the ultrasonic vibration transmitted from the ultrasonic generating means includes transverse vibration and / or width-wise vibration transmitted in the width direction of the cavity in addition to longitudinal vibration, thereby forming It has been found that the thickness of the mold can be reduced while maintaining the quality of the product.
It has also been found that by forming a thin portion in a mold, an optimum vibration can be given to a cavity or a molding material injected into the cavity.
[0007]
Therefore, the invention according to claim 1 includes a movable mold and a fixed mold in which a cavity is formed, and the movable mold or the fixed mold for applying ultrasonic waves to the cavity during injection molding. Ultrasonic injection molding mold having an attached ultrasonic generating means,
The equivalent diameter D of the movable mold and the fixed mold is set to １ ／ or more of the wavelength λ of the ultrasonic vibration generated by the ultrasonic generating means, and the entire movable mold and the fixed mold have a longitudinal vibration. Besides generating transverse vibration and / or widthwise vibration transmitted in the widthwise direction of the cavity,
A thin portion is formed at one or more of the movable mold and the fixed mold.
[0008]
By using such a complex vibration, the amplitude of the vibration transmitted in the width direction of the cavity can be suppressed. In other words, the thickness of the required mold can be reduced to about half compared to the case where only longitudinal vibration is used, so even when a large molded product is injection molded, a relatively thin mold is used. Can be formed.
[0009]
Further, the thin portion can be formed by cutting out a part of the mold or partially forming a hole or a groove. The choice of such a notch, hole, or groove, and in which part of the mold it is formed, depends on the size of the mold, the form of vibration to be applied, the type and temperature of the molding material to be injected, the molded product. It may be appropriately selected in accordance with various conditions such as the shape of the material. In the case of a thin disk-shaped injection molded product, a plurality of notches may be formed radially from the cavity side toward the outer peripheral edges of the movable mold and the fixed mold.
[0010]
Also, when the thickness of the thin portion was set to 0.4 to 0.6 times, preferably 0.5 times the thickness of the mold, an optimal injection molded product could be obtained.
Further, when the equivalent diameter of the mold is D and the wavelength of the vibration transmitted from the ultrasonic wave generating means to the cavity is λ, the width (M) of the thin portion is 0.4 × (D−λ / 2) to 0.6 × (D−λ / 2), preferably 0.5 × (D−λ / 2).
[0011]
Here, the equivalent diameter is expressed as equivalent diameter D = 4 × cross-sectional area / cross-sectional outer peripheral length as defined in Japanese Patent Application Laid-Open No. 10-661. For example, when the cross section of the mold is circular, the equivalent diameter D is equal to the diameter of the mold. When the cross-sectional shape of the mold is rectangular, it is represented by an equivalent diameter D = 2ab / (a + b), [a, b: long and short sides of the mold].
The wavelength (λ) is expressed by dividing the speed (v) at which the sound wave is transmitted through the material forming the mold by the frequency (Hz), that is, λ = v / Hz.
[0012]
In addition to the formation of the thin portion as described above, a synergistic effect can be obtained by imparting a composite vibration as described in claim 1 to the mold.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the ultrasonic injection mold according to the present invention will be described in detail with reference to the drawings.
The present invention is not limited by the following embodiments, and can be variously changed within the scope of the present invention.
FIG. 1 is a cross-sectional side view of a part of a mold for ultrasonic injection molding according to an embodiment of the present invention, and FIG. 2 is a perspective view showing cutouts formed in a fixed mold and a movable mold. FIG. 2 (a) shows a stepped die having a notch formed therein, and FIG. 2 (b) shows a columnar die having a cutout formed therein.
[0014]
[Injection molding range]
In the present invention, the injection molding includes all kinds of injection molding including an injection step, such as multicolor injection molding, injection compression molding, and gas injection molding.
Further, in the injection molding step in the present invention, after the molding material in a molten state is pressed into the cavity from the molding machine, the molding material is molded into a predetermined shape corresponding to the cavity shape, and then cooled and the molded product is taken out. Is included.
[0015]
[Injection molding machine]
The injection molding machine used in the present invention is not particularly limited as long as it can perform the above-mentioned injection molding. In addition, the number of molded products is also arbitrary. In this embodiment, a two-cavity mold having two sets of a fixed mold 3 and a movable mold 4 described in detail below is used.
[0016]
[Mold]
The mold includes a fixed mold 3 and a movable mold 4, and a cavity for molding a molded product by injecting a molding material in a molten state is formed on an abutting surface of both molds.
The fixed mold and the movable mold can be formed of metal, ceramics, graphite, etc., but should be formed of a material with low transmission loss of ultrasonic waves transmitted in the mold, for example, titanium alloy or duralumin. preferable.
[0017]
[Mold composition]
As shown in FIG. 1, the mold for ultrasonic injection molding according to this embodiment is arranged so as to face a fixed mold 3 having a circular cross section having a sprue 5 on a central axis X, and facing the fixed mold 3. And a movable mold 4 having a circular cross section. In this embodiment, the cavity 6 is for molding a thin disk-shaped molded product such as an optical disk, and has a width (a diameter in a circular cavity, hereinafter referred to as a “diameter” in this embodiment) larger than a depth dimension thereof. ) Direction is considerably larger.
[0018]
It is preferable that the equivalent diameter D of the fixed mold 3 and the movable mold 4 is １ ／ or more of the wavelength λ of the ultrasonic vibration generated by the ultrasonic vibrator 7 described later. For example, when the mold is made of duralumin, the speed of the ultrasonic wave transmitted through the duralumin is about 5200 m / s. Therefore, if an ultrasonic wave having a frequency of 15.9 KHz is applied to the mold, the wavelength λ Is about 327 mm. Therefore, the equivalent diameter D is preferably larger than 164 mm.
[0019]
The fixed mold 3 is fixed to the fixed mold fixing plate 2 by a fixed mold holding member 2 ', and the movable mold 4 is fixed to the movable mold fixing plate 10 by a movable mold holding member 10'.
Further, the movable mold fixing plate 10 is attached to the tip of a piston rod of the hydraulic cylinder 11, and moves the movable mold 4 forward and backward with respect to the fixed mold 3 as the piston rod moves forward and backward. The movable mold 4 is closed and opened.
[0020]
[Form of thin part]
Notches 20 (see FIG. 2) are formed in the fixed mold 3 and the movable mold 4 on respective surfaces facing the fixed mold fixed plate 2 and the movable mold fixed plate 10. In FIG. 2, only the movable mold 4 is illustrated, but the same applies to the fixed mold 3, so that illustration is omitted.
A plurality of the notches 20 are formed radially from the center side of the fixed mold 3 and the movable mold 4 toward the outer peripheral edge, and open to the outside of the mold at the outer peripheral edge. The portion where the notch 20 is formed is a portion where the thickness L (the dimension in the direction of the center axis X) of the molds 3 and 4 is reduced, that is, a thin portion.
[0021]
[Form of notch]
One or a plurality of notches 20 are formed so as to divide the outer peripheral edge of the circular shape (in this embodiment, four notches 20 are provided so as to equally divide the outer peripheral edge). The number of the notches 20 and the thickness N of the notches 20 are preferably selected as described above in accordance with various conditions such as the type and temperature of the material to be injected, the shape of the molded product, and the like. .
If the notches 20 having the same shape are formed so as to equally divide the outer peripheral edge of the circular shape as in this embodiment, there is an advantage that the vibration distribution in the cavity 6 can be made uniform. .
[0022]
Although the cross-sectional shape of the notch 20 is arbitrary, various shapes such as a square shape, a wedge shape, a triangular shape, and an arc shape are used depending on the shape of the molded product, the characteristics of the ultrasonic wave to be applied, and the ease of processing. The best one can be selected from the things.
The depth T (dimension in the thickness direction of the mold) of the notch 20 is preferably selected within a range of 0.4 to 0.6 times the thickness L of the mold. Preferably, it is doubled. That is, the thickness of the thin portion of the mold is preferably selected from the range of 0.4 to 0.6 times the thickness L of the fixed mold 3 and the movable mold 4, and is 0.5 times. Is preferred.
The width M (dimension in the direction from the outer edge of the mold toward the center of the mold) is selected from the range of 0.4 × (D−λ / 2) to 0.6 × (D−λ / 2). And preferably 0.5 × (D−λ / 2).
The thickness N (see FIG. 2) of the notch 20 is preferably selected from the range of 0.4 × (D−λ / 2) to 0.6 × (D−λ / 2). 0.5 × (D−λ / 2).
If the depth T, width M, and thickness N are outside the above ranges, the amplitude in the cavity 6 will not be uniform, and it will be impossible to obtain a molded product with good transferability, shrinkage, and birefringence.
The above relationship holds regardless of the shape of the mold. Even if the dies have different shapes as shown in FIGS. 2A and 2B, the notch 20 may be formed so that the depth T, the width M, and the thickness N satisfy the above conditions. In a mold as shown in FIGS. 2A and 2B, it is preferable that the thickness L is 1 / 2λ and the depth of the notch 20 is 1 / 4λ. Note that the cylindrical mold shown in FIG. 2B does not have a flange like the mold shown in FIG. 2A, so that holding the mold becomes a problem. It is preferable that a rod-shaped mold holding member is inserted into each of the above, and the mold is fixed to the mold holding member by welding or screwing.
[0023]
[Other forms of thin part]
The thin portion may be formed by forming slit-shaped grooves in the fixed mold 3 and the movable mold 4. The slit may be formed in a region of the fixed mold 3 and the movable mold 4 in which the cavity is formed, in a shape similar to the cavity 6.
The shape of the slit 20 ′ and the arrangement in the fixed mold 3 and the movable mold 4 are arbitrary, but a portion where the vibration wave transmitted in the width direction of the cavity 6 becomes a node, that is, It is preferably formed at a position of nλ / 4 (n = 1, 3, 5...) In the radial direction of the cavity 6 from the center of the cavity 6 and closest to the outer peripheral edge of the cavity 6.
FIG. 3 shows an example of the arrangement of the slits 20 '.
In the example shown in FIG. 3A, a single slit 20 ′ is formed annularly concentrically with the circular cavity 6. In the example shown in FIG. 3B, two slits 20 ′ are formed in an annular shape concentric with the cavity 6. In the case of the example shown in FIG. 3B, the slit 20 ′ located on the center side of the cavity 6 extends along a concentric circle of the cavity 6 having a radius of nλ / 4 (n = 1, 3, 5,...). It is good to be formed. The thin portion is not limited to the cutout 20 or the slit-shaped groove, but may be formed by a hole or a groove having another shape. It is preferable to select an optimum one according to various conditions such as the size of the mold, the form of vibration to be applied, the type and temperature of the material to be injected, and the shape of the molded product.
[0024]
[Ultrasonic vibrator]
The ultrasonic oscillator may be designed and manufactured in advance so that the resonance frequency of the resonator becomes a frequency that the ultrasonic vibrator 7 can track. In this way, when the nozzle 1 of the molding machine (not shown) is pressed against the sprue 5 and the molten molding material is supplied from the sprue to the cavity, the frequency is always tracked in accordance with the change in the resonance frequency with respect to the load variation. It becomes possible. Further, it is possible to set so as to supply a necessary amount of power according to a change in power consumption of the ultrasonic oscillator.
[0025]
[Vibration frequency]
The vibration frequency of the ultrasonic wave oscillated from the ultrasonic vibrator 7 is preferably 1 KHz to 10 MHz, and is preferably selected within the range of 10 KHz to 100 KHz in order to effectively apply vibration to the molding material at the time of molding. More preferably, it is selected within the range of ２５25 KHz. The amplitude is usually preferably about 20 μm.
Further, the ultrasonic wave oscillated from the ultrasonic vibrator 7 is transmitted by the vibration direction converter 8 and the molds 3 and 4 described below, in addition to the longitudinal vibration, the transverse vibration or the diameter transmitted in the radial direction of the cavity 6. It is converted to include one or both of the directional vibrations. By using such a complex vibration, the amplitude of the vibration transmitted in the radial direction of the cavity 6 can be reduced. That is, if the amplitude transmitted in the radial direction of the cavity 6 is kept the same, the thickness of the fixed mold 3 and the movable mold 4 can be reduced.
[0026]
[Vibration direction converter]
A vibration direction converter 8 is attached to the surface of the movable mold 4 facing the hydraulic cylinder 11 on the central axis X. The vibration direction conversion member 8 can orthogonally convert the vibration input from the vibration input surface and output the vibration input surface from the vibration output surface. Of the two vibration members 8a and 8b constituting the vibration direction conversion member 8, An ultrasonic vibrator 7 as a vibration source is attached to an end face of one vibrating body 8 a orthogonal to the central axis X, and an end face of the vibrating body 8 b parallel to the central axis X is in contact with the movable mold 4. The vibration direction converter 8 can amplify the input vibration and output it to the mold by setting two or three or more vibrators constituting the vibration direction converter 8 to different lengths.
[0027]
The vibration direction converter 8 may be any of a multi-dimensional direction converter such as an LL converter, an LLL converter, or an RL converter. The output of the ultrasonic vibrator 7 is preferably about 1.2 Kw, but when the molds 3 and 4 are large, an RL converter is used, and a plurality of vibration input terminals, for example, By attaching three ultrasonic transducers 7, the total output of the ultrasonic transducer 7 can be tripled.
The amplitude of the ultrasonic wave output from the ultrasonic vibrator 7 is determined according to the fatigue strength of the metal forming the fixed mold 3 or the movable mold 4 against the ultrasonic vibration. For example, the maximum amplitude when using a stainless steel material is about 20 μm, the maximum amplitude for duralumin is about 40 μm, and the maximum amplitude for a titanium alloy is about 100 μm.
[0028]
The vibration generated by the ultrasonic vibrator 7 is converted by the vibration direction converter 8 in the orthogonal direction. In this case, the vibration direction converter 8 and the stationary mold 3 are positioned so that the antinode of vibration resonance is located at the joint between the vibration direction converter 8 and the stationary mold 3. Further, the cavity 6 is located at the antinode of vibration resonance. In this way, the cavity 6 can be vibrated at the maximum amplitude, and the flow of the molding material in the molten state can be optimized.
Further, it is preferable that the resonance node is matched with the fixed mold holding unit, the movable mold holding unit, and the connection between the injection nozzle and the fixed mold. Vibration in this part can be almost eliminated, and loss of vibration energy can be minimized.
[0029]
The nozzle 1 for supplying the molding material to the cavity 6 is connected to the inlet of the sprue 5 of the fixed mold 3. The molding material injected from the nozzle 1 is not particularly limited as long as it is used for ultrasonic injection molding, and examples thereof include thermoplastic resins such as polypropylene and polycarbonate, and metal powders containing these thermoplastics.
[0030]
[Mold release means]
When the fixed mold 3 and the movable mold 4 are opened to remove the molded product, it is preferable to provide a molded product release means for reliably releasing the molded product from the cavity 6.
In this embodiment, a protruding pin 12 as a molded product releasing means is fixed to the movable mold fixing plate 9, and its tip is inserted through the vibration direction converter 8 and the movable mold 4 along the central axis X to form a cavity. Extends to 6. The protruding pin 12 is movable forward and backward by a cylinder (not shown) in order to protrude and remove a molded product molded in the cavity 6.
[0031]
In addition, as the molded product releasing means, the above-mentioned protruding pin 12 which appears and disappears in the cavity 6 at the time of opening the mold is generally used, but other means such as a robot hand for directly taking out the molded product are used. Is also good. Further, the movable mold 4 may be vibrated, or a combination of the vibration of the movable mold 4 and air blow may be used. If the mold release means by vibration is used, it is not necessary to form a punch taper in the fine irregularities formed in the cavity 6 when molding a molded product requiring fine surface processing.
[0032]
[Example]
Hereinafter, the results of an experiment performed using the ultrasonic injection mold of the present invention will be described in comparison with comparative examples.
(1) Example 1
The fixed mold 3 and the movable mold 4 were formed from duralumin 7075, and a square cavity 6 having a diameter of 60 mm × 60 mm × 3 mm was formed in the mold. In addition, two pieces can be obtained so that two molded articles can be obtained by one injection molding.
One ultrasonic vibrator 7 (SONOPET 1200B manufactured by Seidensha Electronics Co., Ltd.) having a fundamental frequency of 15 KHz was attached to the vibration direction converter 8 of the LL converter.
Polycarbonate (Teflon MD-1500 manufactured by Idemitsu Petrochemical Co., Ltd.) was used as a molding material to be injected.
Other conditions are shown below.
Mold shape and dimensions: circular mold, D = 200mm
Vibration wavelength: λ = 338.2 mm D / λ = 0.59
Molding temperature: 320 ° C
Frequency of vibration applied to cavity: 15.9 KHz
Set amplitude: 5 μm
Ultrasonic wave application time: 5 seconds
(2) Comparative example 1
The conditions were the same as (1) except that no ultrasonic wave was applied.
(3) Comparative example 2
The same conditions as in (1) above were used except that no notch was formed.
The transfer rate was measured by performing injection molding under the above conditions, and the results are summarized in Table 1 below. The transfer rate indicates a ratio (h / H) of the filling dimension h of the molding material to the height H from the bottom to the top of the irregularities formed in the cavity 6, as shown in FIG.
[0034]
[Table 1]

[0035]
As is clear from Table 1, the best result was obtained in Example 1 in which the notch 20 was formed and the composite vibration was generated from the ultrasonic vibrator 7. In addition, as shown in Comparative Example 2, an improvement in the transfer rate was observed even when the composite vibration was applied alone, even in the range of D = 0.5λ to 0.6λ.
[0036]
As can be seen from the graph of FIG. 5 showing the vibration state of the cavity 6 in Example 1 and the graph of FIG. 5 showing the vibration state of the cavity surface in Comparative Example 2, FIG. Sufficient amplitude could be obtained almost uniformly over almost the entire area of No. 6.
As can be seen from the graph of FIG. 6, when no cut is formed, the amplitude varies throughout the cavity. A high amplitude is obtained at the center of the cavity, but the amplitude is small near the periphery of the cavity, and a sufficient amplitude is not obtained at that portion.
[0037]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, it is possible to obtain an excellent molded product with high transferability, low shrinkage and low birefringence by simply improving the existing mold.
In particular, even in the injection molding method described in JP-A-10-661, it is possible to improve the quality of a molded product when the equivalent diameter D is in the range of 0.5λ to 0.6λ and in the range of 0.6λ or more. As a result, a large-sized mold can be injection-molded with a large-sized mold.
[Brief description of the drawings]
FIG. 1 is a partially sectional side view schematically showing an ultrasonic injection molding mold according to one embodiment of the present invention.
FIG. 2 is a perspective view showing one embodiment of a notch formed in a mold.
3A and 3B are plan views of a mold showing an example of the arrangement of slits. FIG. 3A shows an example in which a single slit is formed concentrically with a cavity, and FIG. 3B shows two slits. 20 shows an example in which 20 is formed concentrically with the cavity.
FIG. 4 is a diagram for explaining a transfer rate of a molded product in relation to Table 1 in Examples.
FIG. 5 is a graph showing a vibration state of a surface of a cavity in the first embodiment.
FIG. 6 is a graph showing a vibration state of a cavity surface in Comparative Example 2.
[Explanation of symbols]
Reference Signs List 1 Nozzle 2 Fixed mold fixing plate 2 'Fixed mold holding member 3 Fixed mold 4 Movable mold 5 Sprue 6 Cavity 7 Ultrasonic transducer 8 Vibration direction converter 10 Movable mold fixing plate 10' Movable mold holding member 11 Hydraulic cylinder 12 Protruding pin 20 Notch

Claims (7)

A super mold having a movable mold and a fixed mold having a cavity formed therein, and ultrasonic generating means attached to the movable mold or the fixed mold for applying ultrasonic waves to the cavity during injection molding. A mold for sonic injection molding,
The equivalent diameter D of the movable mold and the fixed mold is set to １ ／ or more of the wavelength λ of the ultrasonic vibration generated by the ultrasonic generating means, and the entire movable mold and the fixed mold have a longitudinal vibration. Besides generating transverse vibration and / or transverse vibration transmitted in the width direction of the cavity,
  Ultrasonic injection molding dies, wherein thin portions are formed at one or more of the movable dies and the fixed dies. 2. The ultrasonic injection molding die according to claim 1, wherein a plurality of the thin portions are formed radially from the cavity side toward outer peripheral edges of the movable die and the fixed die. 3. 3. The ultrasonic injection molding according to claim 1, wherein the thickness of the thin portion is 0.4 to 0.6 times the thickness (L) of the fixed mold and the movable mold. Mold. The mold for ultrasonic injection molding according to claim 3, wherein the thickness of the thin portion is 0.5 times the thickness (L) of the fixed mold and the movable mold. When the equivalent diameter of the mold is D and the wavelength of the vibration transmitted from the ultrasonic wave generating means to the cavity is λ, the width (M) of the thin portion is 0.4 × (D−λ / 2). The mold for ultrasonic injection molding according to any one of claims 1 to 4, wherein the diameter is within a range of 0.6 to (D-λ / 2). The mold for ultrasonic injection molding according to claim 5, wherein a thickness (N) between the thin portions is 0.5 × (D−λ / 2). The ultrasonic generator may generate a transverse vibration and / or a width-wise vibration transmitted in a width direction of the cavity, in addition to the longitudinal vibration, in the whole of the fixed mold and the movable mold. Item 7. The ultrasonic injection mold according to any one of Items 1 to 6.

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