JPH0428522A - Extrusion molding method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is an extrusion method that improves the fluidity of the material in a die during extrusion molding of a molding material, thereby improving the productivity of molded products. Regarding the molding method.

[Prior Art] In recent years, molding materials such as plastics have been made to have higher molecular weight or
Increasing the loading of fillers such as inorganic substances is progressing.

However, during extrusion molding, plastic materials improved in this way have poor fluidity within the die, causing surface roughness of the molded product called melt fracture, or the pressure within the die becomes extremely high, causing the die to collapse. In order to prevent the molded product from becoming distorted due to deformation, it has been necessary to lower the extrusion speed, that is, to reduce the production speed.

Therefore, several proposals have been made to solve the above problems by improving the fluidity of the molding material within the die during extrusion molding.

For example, one method is to increase the extrusion speed by increasing the fluidity of the molding material by applying mechanical vibrations to the die of an extrusion molding machine, thereby increasing the extrusion speed. Proposed.

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

That is, since vibrations are forcibly applied to a die that is simply fixed to an extrusion molding machine, there is a problem in that the vibrations are hardly transmitted in reality and a satisfactory result cannot be obtained.

The present invention has been made in view of the above problems, and
By effectively applying ultrasonic vibration to the dice,
It transmits vibrations efficiently, improves the fluidity of especially highly viscous molding materials in the die, dramatically improves the productivity of extrusion molding, and uses these materials to make ultra-thin molds.

The objective was to provide an extrusion molding method that could extrude extremely thin products.

[Means for Solving the Problems] In order to achieve the above object, the extrusion molding method of the first invention includes:
In a method of extruding a molding material by applying vibrations to a die, the vibrations are transmitted to the molding material at the die extrusion port perpendicular to the outflow direction, and molding is performed while causing the die to resonate at n wavelengths. This is the method.

In addition, in the extrusion molding method of the second invention, in order to efficiently produce the vibration effect of the first invention, molding is performed by aligning the extrusion opening of the die with the abdomen of resonance caused by vibration, that is, the position where the vibration effect is greatest. Here's how to do it.

[Example] A specific example of the above solution will be described below.

First, a specific example of an extrusion molding apparatus for carrying out the present invention will be explained based on FIG.

In the figure, 1 is a die, which is divided into a die member 2 and a die member 3. An extrusion port 1b is provided on the contact surface of the die member 2 with the die member 3. The die l can be made of various materials such as metal, ceramics, graphite, etc. Among these materials, it is preferable to use a material with low vibration transmission loss at the molding temperature. In particular, aluminum, duralumin,
Titanium alloy, graphite or preferred.

In addition, it is preferable that the contact surfaces of the die member 2 and the die member 3, which are divided in this way, be in surface contact as much as possible in order to transmit vibrations efficiently, and depending on the shape of the molded product to be molded, , it is also possible to make the die l into an undivided, integral type, or conversely into three or more parts. When dividing the die 1, it is preferable that the dividing surface of the die 1 be provided as close as possible to the resonance region caused by the vibration so that vibrations can be transmitted efficiently.

Reference numeral 4 denotes a nozzle of an extrusion molding machine (not shown), which supplies the molding material to the die 1 through the inlet 1a, and finally extrudes the molding material from the extrusion port ib. Further, the nozzle 4 is attached to the die member 3 by a mounting means such as a screw at a position approximately at a node of vibration (displacement waveform) in the die member 3.
is fixed.

5 and 6 are die member 2 and die member 3, respectively.
There are flanges as holding members provided at the positions of the resonance nodes of the die members 2 and 3 due to ultrasonic waves, respectively.

This flange 5.6 is preferably made as thin as possible in order to prevent vibrations from flowing out from the die 1 and to reduce vibration loss in this portion.

Bolts 7 uniformly tighten the die members 2 and 3 via flanges 5 and 6. Further, in order to suppress vibrations from the die l from flowing out, it is preferable that the bolt 7 does not touch the die l.

8 is an ultrasonic vibrator, and an inlet 2a to the die member 2
The tip end thereof is brought into contact with the die surface on the opposite side, and is connected with a mounting member 9 such as a screw.

A horn capable of converting the amplitude of the ultrasonic vibrator 8 can be coupled between the ultrasonic vibrator 8 and the die member 2. Furthermore, it is preferable that the ultrasonic vibrator 8 and the die member 2 be coupled together through the resonance region of the ultrasonic waves in order to improve the transmission efficiency of ultrasonic vibrations.

Note that the vibration generator that causes the dice 1 to resonate may be any device that has a vibration frequency of 101 (z to 10 MHz), such as an ultrasonic device, an electrodynamic device, a hydraulic device, or the like.

Furthermore, if the die member 3 having the function of an L-L converter conventionally used for converting the direction of ultrasonic vibration is used, the ultrasonic wave will be placed on the die surface in a position perpendicular to the coupling direction of the nozzle 4. It is also possible to couple acoustic transducers.

Reference numeral 10 denotes an ultrasonic oscillator, which causes an ultrasonic vibrator 8 to generate ultrasonic vibrations, and excites the die 1 at a resonance frequency, thereby causing the die l to resonate.

The resonance frequency of this die l is designed and manufactured to a frequency that can be tracked by the ultrasonic oscillator.The molding material is supplied to the die l from the nozzle 4 of the extrusion molding machine, and finally the extrusion port 1b The system constantly tracks slight changes in the resonant frequency due to momentary load fluctuations as the molding material is extruded from the molding material, and the required amount of power (below the maximum output) is adjusted according to the momentary changes. ). In other words, automatic frequency tracking and automatic power control methods are adopted.

Also, the vibration mode of the die is longitudinal vibration.

It is possible to use known vibration modes such as transverse vibration, torsional vibration, radial vibration, and flexural vibration.

In the present invention, vibration is applied to the die, and the vibration is transmitted perpendicularly to the direction in which the molding material flows out.

Next, a specific example of the extrusion molding method of the present invention carried out using the above extrusion molding apparatus will be described.

A nozzle 4 of a molding machine (not shown) is connected to the die member 3,
A molding material is supplied to the die l to perform extrusion molding, and an ultrasonic oscillator lO generates ultrasonic vibrations in the ultrasonic vibrator 8, thereby causing the die l tt n wavelength resonance.

Can the vibration frequency be arbitrarily selected?

In order to make the vibration effect extremely effective on the fluidized material, it is preferable to set the frequency to 10 KH, to 100 KM.

In addition, n in n-wavelength resonance may be m/2 (m: a positive integer) (Figure 2), or n<3 in order to reduce the loss of ultrasonic vibration of all dies. preferable.

Furthermore, in order to effectively improve the fluidity of the molding material, the amplitude of the ultrasonic vibration applied to the die l should be set to o, ig■ ~
It is preferable to set it to 50 gm.

Molding materials that can be molded by the extrusion method described above include organic materials such as plastics, inorganic polymers, ceramics, metals, S* materials such as glass, other foodstuffs, and mixed materials thereof. Examples include materials that have fluidity. In particular, when applied to plastics, the occurrence of melt fractures is reduced and molded products with high product value can be obtained.

Moreover, the extrusion molding method in the present invention includes inflator molding, sheet molding, and round bar molding.

Vibe molding, profile extrusion molding, multilayer extrusion molding, blow molding,
It refers to all molding methods such as wire coating, monofilament molding, etc. in which a molding material in a fluid state is passed through a die in order to extrude it into a predetermined shape.

The extrusion molding method of the present invention is also applicable to pultrusion molding, which is basically similar to extrusion molding.

In that case as well, a remarkable effect can be found in suppressing surface roughness of the molded product.

[Experimental Example] Hereinafter, the results of an experiment conducted using the extrusion molding method of the present invention will be explained while comparing with a comparative example.

Experimental Example 1 Extrusion molding apparatus: Apparatus vibration mode shown in FIG. 1: Longitudinal vibration Under the above conditions, the die was resonated to perform double extrusion molding, and the occurrence of melt fractures at that time was investigated. In addition, we measure the time until the surface temperature of the extrudate stabilizes, and further measure the pressure inside the nozzle, which is a measure of the flow resistance of the molding material generated from the nozzle to the die, at the point when the surface temperature of the extrudate stabilizes. The measurement was made at an extrusion rate of 0.5 g/hr.

Fruit 1 11 The experiment was conducted under the same conditions as in Experimental Example 1, except that the die 1 was used, with the extrusion port 1b positioned at the antinode position due to ultrasonic resonance.

The results of Experimental Examples 1 and 2 are shown in Table 1.

In addition to using the device shown in Figure 4, the shape of the die extrusion port,
The experiment was conducted under the same conditions as in Experimental Example 2, including the fact that the shape of the lip portion land was the same as in Experimental Example 2.

Comparative Example 2 An experiment was conducted under the same conditions as Experimental Example 1 except that the ultrasonic oscillation was stopped.

Comparative Example 3 As shown in FIG. 5, an experiment was conducted under the same conditions as Experimental Example 1, except that the ultrasonic transducer 8 was pressed against the joint position of the die members 2 and 3. At this time, the dice were not resonating.

The results of Comparative Examples 1, 2 and 3 are shown in Table 1.

[Left below] As a result, by applying vibrations, especially ultrasonic waves, to make the T-die resonate, the flow resistance of the molding material is reduced, and the occurrence of melt fractures can be suppressed even at extremely high extrusion speeds. It has been found that this method can improve productivity.

In particular, if vibrations are transmitted to the molding material at the die extrusion port perpendicular to the direction in which it flows out, the temperature rise of the molding material due to the vibrations can be reduced. It was found that it was possible to significantly reduce the

[Effects of the Invention] As described above, according to the extrusion molding method of the present invention, vibrations are efficiently transmitted by effectively applying vibrations to the die, and by utilizing the resonance abdomen, molding material, In particular, it is possible to improve the fluidity of materials with poor fluidity in the die, reduce the occurrence of melt fractures, significantly reduce the loss at the start-up of molding, and dramatically improve the productivity of extrusion molding. I can do it.

[Brief explanation of drawings]

Fig. 1 is a cutaway side view of essential parts of a specific example of an extrusion molding apparatus for implementing the present invention, Fig. 2 is an explanatory diagram of the displacement waveform and wavelength of ultrasonic vibration in the extrusion molding method of the present invention, and Fig. 3 is an explanatory diagram of the displacement waveform and wavelength during die resonance in the extrusion molding device used in Experimental Example 1, FIG. 4 is a cutaway side view of the main part of the extrusion molding device used in Comparative Example 1, and FIG. Figure 3 shows a schematic diagram of another device using a child. 1: Dice 2, 3: Dice members la, lb
: Inflow port 1b: Extrusion port 5.6: Dice holding part 8: Ultrasonic vibrator 10: Ultrasonic oscillator

Claims (2)

[Claims] (1) In a method of extruding a molding material by applying vibration to a die, the vibration is transmitted to the molding material at the die extrusion port perpendicular to the outflow direction, and the die is made to resonate at n wavelengths. An extrusion molding method characterized by molding. (2) The extrusion molding method according to claim 1, characterized in that the molding is performed while resonating so that the resonance region due to the vibration coincides with the position of the extrusion opening of the die.