JP2001001370A - Ultrasonic injection mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic injection mold capable of further enhancing a high transfer property, a low shrinkage factor and low double refraction only by applying simple improvement to the mold and enabling the injection molding of a large-sized molded article. SOLUTION: In an ultrasonic injection mold having a movable mold 4 and a fixed mold 3 between which a cavity is formed and the ultrasonic wave generation means 7 attached to the movable mold 4 or fixed mold 3 in order to apply ultrasonic waves to the cavity at a time of injection molding, notches 20 are formed to one places or a plurality of places of the movable mold 4 and the fixed mold 3 to provide thin-walled parts. Lateral vibration and/or radial vibration transmitted in the radial direction of the cavity may be generated from the ultrasonic generation means 7 other than vertical vibration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. 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 having excellent transferability and capable of effectively preventing the occurrence of birefringence and warpage.

[0002]

2. Description of the Related Art Conventionally, in injection molding of a molding material such as a resin, in order to obtain an injection molded product having high transferability and low shrinkage, injection molding is performed while applying ultrasonic vibration to the molding material during the injection molding. There are known ways to do this. For example,
Japanese Patent Application Laid-Open No. 7-2088 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. I have. Also, Japanese Patent Laid-Open No.
Japanese Patent Publication No. 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.

However, in the above-described conventional ultrasonic molding method, ultrasonic waves must be locally applied to a mold in order to efficiently apply ultrasonic waves, and this method is not suitable for large molded products and is not suitable for the mold. There was a problem that the structure became complicated. In order to solve such a problem, the applicant of the present application has disclosed in
No. 661 discloses an injection molding method 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. According to this method, the optimal equivalent diameter D of the mold can be selected in accordance with 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, in recent years, demands for precision injection molding have been increasing, and there has been a demand for injection molding having higher transferability, lower shrinkage, and lower birefringence. However, in the injection molding method described in Japanese Patent Application Laid-Open No. 10-661, although the equivalent diameter D satisfies the above-mentioned requirement in a mold having a diameter of 0.5λ or less, when the equivalent diameter D is 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. Further, 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]

SUMMARY OF 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 by simply improving the mold. Particularly, in the injection molding method described in JP-A-10-661, the equivalent diameter D is 0.5λ.
An object of the present invention is to provide a mold for ultrasonic injection molding capable of obtaining a molded article having excellent transferability, low shrinkage, and low birefringence when injection molding a large molded article exceeding the above.

[0006]

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 wave generating means includes transverse vibration and / or width-directional 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.

Therefore, the invention according to claim 1 provides a movable mold and a fixed mold having a cavity formed on an abutting surface thereof and the movable mold for applying ultrasonic waves to the cavity during injection molding. An ultrasonic injection molding die having a mold or ultrasonic generating means attached to the fixed die, wherein the ultrasonic generating means applies transverse vibration and / or Alternatively, it is configured to generate widthwise vibration transmitted in the widthwise direction of the cavity. 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 required thickness of the 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. The molding can be performed by using.

According to a second aspect of the present invention, there is provided a mold for ultrasonic injection molding, wherein a movable mold and a fixed mold having a cavity formed on an abutting surface, and an ultrasonic wave is applied to the cavity during injection molding. An ultrasonic generating means attached to the movable mold or the fixed mold to perform the ultrasonic injection molding, wherein the movable mold and the fixed mold have a thin wall at one or more positions. It is configured by forming a part.

In the thin portion, a part of the mold is cut out,
It can be formed by 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 according to 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.

Further, when the thickness of the thin portion is set to 0.4 to 0.6 times, preferably 0.5 times the thickness of the mold, an optimum injection molded product can 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), and 0.5 × (D−λ /
2) is preferable.

Here, the equivalent diameter is disclosed in JP-A-10-661.
As defined in the publication, the equivalent diameter D is expressed by D = 4 × cross-sectional area / cross-sectional outer peripheral length. 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 section of the mold is rectangular, the equivalent diameter D
= 2ab / (a + b), [a, b: long side and short side of mold]. In addition, the wavelength (λ) indicates the speed (v) at which a sound wave is transmitted through the material forming the mold, and the frequency (Hz).
, Ie, λ = v / Hz.

[0012] In addition to forming 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]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a mold for ultrasonic injection molding according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited at all by the following embodiments, and can be variously modified within the scope of the present invention. FIG. 1 is a side view showing a cross section of a part of an ultrasonic injection molding die according to an embodiment of the present invention, and FIG. 2 is a perspective view showing cutouts formed in a fixed die and a movable die. FIG. 2 (a) shows a stepped mold with cutouts, and FIG. 2 (b) shows a cylindrical mold with cutouts.

[Injection Molding Range] In the present invention, injection molding includes all types 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 of the present invention, a molding material in a molten state is press-fitted into a cavity from a molding machine, the molding material is molded into a predetermined shape according to the cavity shape, and then cooled and a molded product is taken out. Is included.

[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.

[Mold] The mold includes a fixed mold 3 and a movable mold 4
A cavity for molding a molded product by injecting a molding material in a molten state is formed on the contact surfaces 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.

[Structure of Die] As shown in FIG. 1, the mold for ultrasonic injection molding of this embodiment has a fixed die 3 having a circular cross section having a sprue 5 on a center axis X, and a fixed die 3 having the same. And a movable mold 4 having a circular cross section arranged opposite to the mold 3. 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.

The equivalent diameter D of the fixed mold 3 and the movable mold 4
Is preferably 以上 or more of the wavelength λ of the ultrasonic vibration generated by the ultrasonic vibrator 7 described later. For example,
When the mold is formed 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.

The fixed die 3 is fixed to the fixed die fixing plate 2 by a fixed die holding member 2 ', and the movable die 4 is fixed to the movable die fixing plate 10 by a movable die 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 clamped and opened.

[Form of Thin Section] In the fixed mold 3 and the movable mold 4, notches 20 (see FIG. 2) are formed on respective surfaces facing the fixed mold fixed plate 2 and the movable mold fixed plate 10. Is formed. In FIG. 2, only the movable mold 4 is shown, but the same applies to the fixed mold 3, so that the 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. This notch 20
Is a portion where the thickness L (the dimension in the direction of the central axis X) of the molds 3 and 4 is reduced, that is, a thin portion.

[Form of Notch] One or more notches 20 are formed so as to divide the outer peripheral edge of the circular shape (in this embodiment, four notches 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
As described above, it is preferable to select an optimum material according to 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. .

The sectional shape of the notch 20 is optional,
Depending on the shape of the molded product, the characteristics of the ultrasonic wave to be applied, the ease of processing, etc., it is possible to select the optimal one from various shapes such as square, wedge, triangle, arc, etc. . 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 preferably 0.5 times. Is preferred. Width M (dimension in the direction from the outer edge of the mold to the center of the mold)
Is 0.4 × (D−λ / 2) to 0.6 × (D−λ / 2)
0.5 × (D−λ / 2)
It is preferred that The thickness N of the notch 20 (see FIG. 2) is 0.4 × (D−λ / 2) to 0.6 × (D−
λ / 2), and it is preferable to select 0.5 × (D−
λ / 2). Depth T, width M and thickness N
Is out of the above range, the amplitude in the cavity 6 becomes non-uniform, and it becomes impossible to obtain a molded product having 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, the thickness L is reduced to 1 /
2λ, and the depth of the notch 20 is preferably １ ／ λ. Note that the cylindrical mold as shown in FIG. 2 (b) does not have a flange like the mold of FIG. 2 (a). It is preferable that a bar-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.

[Another form of thin portion] 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 similar shape to the cavity 6. Further, the shape of the slit 20 ′ and how it is arranged 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, In the radial direction of the cavity 6 from the center of the cavity 6, nλ / 4 (n
= 1, 3, 5...) 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.
The slit 20 ′ located on the center side of the cavity 6 has n
Cavity 6 having a radius of λ / 4 (n = 1, 3, 5,...)
It is good to be formed along the concentric circle of. 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 the most suitable 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, the shape of the molded product, and the like.

[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 molding material in a molten state is supplied from the sprue to the cavity, the frequency is always tracked according to 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.

[Vibration Frequency] The vibration frequency of the ultrasonic wave oscillated from the ultrasonic vibrator 7 is preferably 1 KHz to 10 MHz, and is set within the range of 10 KHz to 100 KHz in order to effectively apply vibration to the molding material during molding. Preferably, it is selected, and more preferably, it is selected within the range of 15 KHz to 25 KHz. The amplitude is usually preferably about 20 μm. Further, the ultrasonic wave oscillated from the ultrasonic vibrator 7 is transmitted to the vibration direction converter 8 and the molds 3 and 4 described below.
Thus, the vibration is converted to include one or both of the lateral vibration and the radial vibration transmitted in the radial direction of the cavity 6 in addition to the longitudinal vibration. By using such a composite 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.

[Vibration direction converter] A vibration direction converter 8 is mounted on the central axis X on the surface of the movable mold 4 facing the hydraulic cylinder 11 side. 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 8a orthogonal to the central axis X, and the vibrating body 8 parallel to the central axis X is provided.
The end face of b is in contact with the movable mold 4. Vibration direction converter 8
By making the two or three or more vibrating bodies constituting the vibrating direction converting body 8 different in length, it becomes possible to amplify the input vibration and output it to the mold.

The vibration direction converter 8 is an LL converter, an L-
Any of the multi-dimensional direction converters of the LL converter and the RL converter may be used. The output of the ultrasonic vibrator 7 is 1.2 Kw
Although it is preferable to use a mold having a size of about 3 mm, when the molds 3 and 4 are large, an RL converter is used, and a plurality of, for example, three ultrasonic vibrators 7 are attached to the vibration input end. The total output of the ultrasonic vibrator 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, when a stainless steel material is used, the maximum amplitude is about 20 μm.
m, the maximum amplitude for duralumin is about 40 μm, and the maximum amplitude for titanium alloy is about 100 μm.

The vibration generated by the ultrasonic vibrator 7 is
The vibration is converted in the orthogonal direction by the vibration direction converter 8. 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. By doing so, 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 made to coincide with the fixed die holding portion, the movable die holding portion, and the connection portion between the injection nozzle and the fixed die. Vibration in this portion can be almost eliminated, and loss of vibration energy can be minimized.

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.
Thermoplastic resins such as polypropylene and polycarbonate,
Examples thereof include metal powders containing these thermoplastics.

[Mold release means] Mold release means for reliably releasing the molded article from the cavity 6 when the fixed mold 3 and the movable mold 4 are opened to remove the molded article. Is preferably provided. 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.

As the molded product releasing means, the above-mentioned protruding pin 12 which comes and goes in the cavity 6 when the mold is opened is generally used, but other means such as a robot hand for directly removing the molded product are used. It may be. Also,
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 article requiring fine surface processing.

[Examples] Hereinafter, the results of experiments performed using the ultrasonic injection mold of the present invention will be described in comparison with comparative examples. (1) Example 1 A fixed mold 3 and a 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 were obtained so that two molded articles could be obtained by one injection molding. L-
The vibration direction converter 8 of the L converter has a fundamental frequency of 15 KH.
z ultrasonic transducer 7 (SONOP manufactured by Seidensha Electronics Co., Ltd.)
ET1200B). Polycarbonate (made by Idemitsu Petrochemical Co., Ltd.)
Toughlon MD-1500) was used. Other conditions are shown below. Mold shape and dimensions: circular mold, D = 200 mm Vibration wavelength: λ = 338.2 mm D / λ = 0.59 Molding temperature: 320 ° C. Frequency of vibration applied to cavity: 15.9 KHz Setting amplitude: more than 5 μm Sound wave application time: 5 seconds

(2) Comparative Example 1 The same conditions as in (1) were used 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 is, as shown in FIG. 4, the ratio 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 (h / H).
Is shown.

[0034]

[Table 1]

As is apparent from Table 1, the best results were 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, D = 0.5λ-
Even within the range of 0.6λ, an improvement in the transfer rate was observed.

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, the graph of FIG. As a result, a sufficient amplitude could be obtained almost uniformly over almost the entire cavity 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]

According to the present invention, it is possible to obtain an excellent molded product having 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 molded product 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 an embodiment of the present invention.

FIG. 2 is a perspective view showing one embodiment of a notch formed in a mold.

FIG. 3 is a plan view of a mold showing an example of arrangement of slits.
FIG. 3A shows an example in which a single slit is formed concentrically with the cavity, and FIG. 3B shows an example in which two slits 20 are 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 cavity surface in the first embodiment.

FIG. 6 is a graph showing a vibration state of a cavity surface in Comparative Example 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle 2 Fixed mold fixing plate 2 'Fixed mold holding member 3 Fixed mold 4 Movable mold 5 Sprue 6 Cavity 7 Ultrasonic vibrator 8 Vibration direction converter 10 Movable mold fixing plate 10' Movable mold holding member 11 Hydraulic cylinder 12 Protruding pin 20 Notch

Claims (8)

[Claims] 1. A movable mold and a fixed mold having a cavity formed therein, and an ultrasonic generator attached to the movable mold or the fixed mold to apply ultrasonic waves to the cavity during injection molding. Means for ultrasonic injection molding, comprising: a transverse vibration and / or a width direction vibration transmitted in a width direction of the cavity, in addition to the longitudinal vibration, to the entire movable mold and the fixed mold. A mold for ultrasonic injection molding characterized by generating. 2. A movable mold and a fixed mold having a cavity formed therein, and an ultrasonic generator attached to the movable mold or the fixed mold for applying ultrasonic waves to the cavity during injection molding. Means for forming a thin wall at one or a plurality of positions of the movable mold and the fixed mold. 3. The ultrasonic injection molding metal according to claim 2, wherein a plurality of the thin portions are radially formed from the cavity side toward outer peripheral edges of the movable mold and the fixed mold. Type. 4. The method according to claim 2, 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. Ultrasonic injection mold. 5. The ultrasonic injection molding metal according to claim 4, wherein the thickness of the thin portion is 0.5 times the thickness (L) of the fixed mold and the movable mold. Type. 6. When the equivalent diameter of the mold is D and the wavelength of 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 ultrasonic injection molding die according to any one of claims 2 to 5, wherein the diameter is within a range of 0.6 x (D-λ / 2). 7. The thickness (N) between the thin portions is 0.5 ×
The ultrasonic injection molding die according to claim 6, wherein (D-λ / 2). 8. The ultrasonic wave generating means generates transverse vibration and / or widthwise vibration transmitted in the widthwise direction of the cavity, in addition to longitudinal vibration, in the whole of the fixed mold and the movable mold. The mold for ultrasonic injection molding according to any one of claims 2 to 7, wherein