Patent Application
20140182347
1. Field of the Invention
The present invention relates generally to ultrasonic extrusion apparatuses which cause resonance of extrusion dies using ultrasonic vibrations, thus reducing friction between the extrusion dies and extrusion materials and, more particularly, to an ultrasonic extrusion apparatus which has an increased number of ultrasonic vibrators provided around the extrusion die in a circumferential direction to increase the vibration output, whereby when extruding a metal material such as a magnesium material, friction between the metal material and the extrusion die can be reduced, thus improving the performance of the extrusion process (preventing a reduction in an extrusion rate, generation of heat, cracking of a product, errors in measurements, etc.).
2. Description of the Related Art
Generally, it is difficult to shape a metal material such as a magnesium material because of friction between tools and the material to be shaped.
For this reason, an extrusion method is mainly used to shape a metal material. Typically, as shown in
This metal extrusion method is a method which is used to manufacture high-density and high-quality products at a high production rate. However, the conventional extrusion method has many problems which occur because of friction between the extrusion die 10 and the metal material 20 to be extruded.
To overcome these problems, as shown in
In the conventional ultrasonic resonance system 50, two ultrasonic vibrators 40 are respectively provided on upper and lower portions of too extrusion die 10. The ultrasonic vibrators 40 generate ultrasonic waves. For this, an ultrasonic wave generator 60, first and second amplifiers 62 and 64, a pressure controller 66, an oscilloscope 68, a heater controller 70, etc. are connected to the ultrasonic vibrators 40.
In detail, the ultrasonic wave generator 60 outputs a voltage at 10V in a from of sine wave to operate the ultrasonic vibrators 40. Each of the first and second amplifiers 62 and 64 amplifies the voltage output from the ultrasonic wave generator 60 to from 10 to 100 times and supplies it to the corresponding ultrasonic vibrator 40.
Furthermore, the pressure controller 66 controls a piston 72 of a double-acting extruder with a pressure ranging from 0 ton to 500 tons. The oscilloscope 68 measures the voltage and current applied to the ultrasonic vibrators 40. The heater controller 70 maintains the temperature of extrusion material (magnesium) 20, which is approximately 200° C., so that the extrusion material 20 is prevented from being cooled.
As shown in
However, as shown in
Furthermore, a plurality of mounting holes 16 are formed in a circumferential outer surface of the die body 12 at diametrically opposite positions. The two ultrasonic vibrators 40 are fastened to two portions of the die body 12 through the corresponding amounting holes 16 end apply vibrations to the extrusion die 10.
However, in the conventional extrusion die 10, a front surface of the die body 12 is a planar surface and is brought into direct contact with the extrusion material 20. Thus, extrusion pressure, ranging from about 90 tons to about 150 tons, for extruding the extrusion material 20 is directly transmitted to the front surface of the die body 12. A rear surface of the die body 12 is also planar, is brought into close contact with a front surface of the die holder 84, and is reliably integrally fixed to the die holder 84.
Therefore, in the case of the conventional extrusion die 10, even if vibrations are applied from the ultrasonic vibrators 40 to the extrusion die 10, they are disturbed by high extrusion pressure of the extrusion material 20 and dispersed to the outside through the die holder 84. Thus, the vibrations cannot be effectively transmitted to the extrusion die 10, so it is difficult to obtain a satisfactory vibration effect. Moreover, a phenomenon in which a vibration mode deviates from normal conditions is also caused.
In addition, because only the two ultrasonic vibrators 40 that are disposed on the upper and lower portions of the die body 12 apply vibrations to the die body 12 in the directions facing each other, vibrations cannot be evenly applied to the overall shaping space in the extrusion die 10, but vibrations are partially applied to only the upper and lower portions of the die body 12, thus greatly reducing substantial ultrasonic vibration effect.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an ultrasonic extrusion apparatus for metal material which is configured such that vibrations generated from ultrasonic vibrators mounted to an extrusion die are effectively transmitted to the extrusion die, whereby when an extrusion process is conducted, friction between the extrusion die and the metal material is minimized so that high-density and high-quality metal products can be manufactured at a high production rate.
Another object of the present invention is to provide an ultrasonic extrusion apparatus for metal material in which pressure required to shape the metal material that is applied to a front surface of the extrusion die can be minimized, and outward dispersion of vibrations transmitted from the ultrasonic vibrator to the extrusion die can be minimized, so that vibrations generated from the ultrasonic vibrators can be more effectively transmitted to the extrusion die while the extrusion process is being carried out.
In order to accomplish the above object, the present invention provides an ultrasonic extrusion apparatus for extruding a metal material in such a way that an extrusion die is resonated by ultrasonic vibrations, the ultrasonic extrusion apparatus including: a die body disposed between an extrusion piston end a die holder; front and rear conical surfaces respectively formed on front and rear surfaces of the die body, each of the front and rear conical surfaces being concave; an extrusion hole passing through central portions of the front and rear conical surfaces, the extrusion hole being defined by a first inner diameter part through which the metal material is actually extruded and a second inner diameter part having a diameter larger than the first inner diameter part so that the metal material that has passed through the first inner diameter part is prevented from coding into contact with the second inner diameter part; and a plurality of ultrasonic vibrators mounted to a circumferential outer surface of the die body, the ultrasonic vibrators applying the ultrasonic vibrations to the die body, wherein the ultrasonic vibrators are arranged around the circumferential outer surface of the die body to be symmetrical based on the extrusion hole so that the ultrasonic vibrations are evenly applied to the die body.
Furthermore, a plurality of chamfering surfaces may be formed on the circumferential outer surface of the die body at positions spaced apart from each other at regular intervals with respect to a circumferential direction, a mounting hole may be formed in a central portion of each of the chamfering surfaces, and the ultrasonic vibrators may be mounted to the respective chamfering surfaces through the corresponding mounting holes.
The chamfering surfaces may comprise six chamfering surfaces formed on the circumferential outer surface of the die body, and the ultrasonic vibratos may comprise six ultrasonic vibrators mounted to the respective six chamfering surfaces through the corresponding six mounting holes.
The ultrasonic extrusion apparatus may further include a cylindrical jig disposed on the front conical surface of the die body, wherein the extrusion piston may be disposed in the jig so that a shaping pressure is formed in the jig, thus reducing an extruding pressure applied to the front conical surface of the die body.
The ultrasonic extrusion apparatus may further include a vibration isolation unit disposed between the rear conical surface of the die body and the die holder to reduce a vibration transmitted from the die body to the die holder, the vibration isolation unit including: front and rear circular plates disposed facing each other; and a connector disposed inside the front and rear circular plates, wherein front surfaces of the front circular plate and connector may be closely fixed to a rear surface of the die body, and rear surfaces of the rear circular plate and connector may be closely fixed to a front surface of the die holder, and a through hole may be formed in a central portion of the connector so that the extrusion hole communicates with an internal space of the die holder through the through hole.
The through hole of the connector may have a diameter larger than the diameter of the extrusion hole of the die body.
In an ultrasonic extrusion apparatus according to the present invention, front and rear conical surfaces that are concave are respectively formed on front and rear surfaces of a die body which is disposed between an extrusion piston and a die holder. In addition, a cylindrical jig is provided on the front conical surface. Thereby, extrusion pressure which is transmitted to the front surface of the die body can foe markedly reduced.
Furthermore, a vibration isolation unit is installed between the rear conical our face of the die body and a die holder so that vibrations which are transmitted from the die body to the die holder can be markedly reduced.
Moreover, a plurality of ultrasonic vibrators which apply vibrations to the extrusion die are arranged around the extrusion die in the circumferential direction so that vibrations can be evenly applied to the entirety of extrusion die. Therefore, vibrations which are generated from the ultrasonic vibrators mounted to the extrusion die can be effectively transmitted to the extrusion die so that friction between the metal material and the extrusion die can be minimized during the extrusion process.
Ultimately, compared to the conventional ultrasonic extrusion apparatus, the ultrasonic extrusion apparatus of the present invention can produce high-density and high-quality metal products at a high production rate.
The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.
Reference now should be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components.
An ultrasonic extrusion apparatus 100 for metal material according to the present invention is used in an ultrasonic resonance system which shapes metal extrusion material while resonance of the extrusion die 110 is caused by ultrasonic vibrations. As shown in
The die body 130 forms a main body of the extrusion die 110. Front and rear conical surfaces 132 and 134 which are concave are respectively formed in front and rear surfaces of the die body 130.
In detail, as shown in
The extrusion hole 140 is defined both by a first inner diameter part 142 which actually extrudes material, and by a second inner diameter part 144 which has a diameter larger than that of the first inner diameter part 142 so that the extrusion material that has passed through the first inner diameter part 142 does not make contact with the second inner diameter part 144. It can be understood that the extrusion hole 140 is reduced in size compared to the conventional structure shown in
Furthermore, the ultrasonic extrusion apparatus 100 according to the present invention includes a plurality of ultrasonic vibrators 150 which are provided on a circumferential outer surface of the die body 130 to apply ultrasonic vibrations to the die body 130.
The ultrasonic vibrators 150 are respectively fastened into mounting holes 130 which are formed in the circumferential outer surface of the die body 130 at positions spaced apart from each other at regular intervals with respect to the circumferential direction. In an embodiment, preferably, six mounting holes 138 are forced at regular circumferential intervals, and six ultrasonic vibrators 150 are fastened into the respective mounting holes 138 so that ultrasonic vibrations are applied to the die body 130.
To install the ultrasonic vibrators 150 on the die body 130, the circumferential outer surface of the die body 130 is diametrically symmetrical based on the extrusion hole 140. In addition, chamfering surfaces 136 are formed on the circumferential outer surface of the die body 130 and spaced apart from each other at regular intervals in the circumferential direction.
The mounting holes 138 are respectively formed in central portions of the chamfering surfaces 136. The ultrasonic vibrators 150 are mounted to the respective chamfering surfaces 136 by the corresponding mounting holes 138.
The mounting structure or the ultrasonic vibrators 150 is illustrated in detail in
As such, in the ultrasonic extrusion apparatus 100 for metal material according to the present invention, the sin ultrasonic vibrators 150 are arranged around the circumferential outer surface of the die body 130 of the extrusion die 110, whereby vibrations can be uniformly applied to the overall portion of the extrusion die 110.
The ultrasonic extrusion apparatus 100 according to the present invention further includes a cylindrical jig 160 which is disposed on the front conical surface 132 of the die body 130.
As shown in
Furthermore, an extrusion piston 120 is disposed in the jig 160. A heater 162 is provided around a circumferential outer surface of the jib 160.
When the extrusion operation is conducted, the extrusion piston 120 is operated in the jig 160 that has the cylindrical structure, so that shaping pressure is formed in the jib 160, and extrusion pressure transmitted to the front conical surface 132 of the die body 130 can be markedly reduced.
The ultrasonic extrusion apparatus 100 according to the present invention further includes a vibration isolation unit 170 which is disposed between the rear conical surface 134 of the die body 130 and the die holder 122.
The vibration isolation unit 170 includes front and rear circular plates 172a and 172b which face each other, a connector 176 which is disposed inside the front and rear circular plates 172a and 172b, and a plurality of springs 178 which are provided between the front and rear circular plates 172a and 172b.
Front surfaces of the front circular plate 172a and connector 176 of the vibration isolation unit 170 are closely fixed to a rear surface of the die body 130. Rear surfaces of the rear circular plate 172b and connector 176 are closely fixed to a front surface of the die holder 122.
Furthermore, a through hole 176a is formed in a central portion of the connector 176 so that the extrusion hole 140 communicates with the internal space 122a of the die holder 122 through the through hole 176a. The diameter of the through hole 176a of the connecter 176 is larger than that of the extrusion hole 140 of the die body 130.
The vibration isolation unit 170 having the above-mentioned construction functions to reduce vibrations transmitted from the die body 130 to the die holder 122.
In the ultrasonic extrusion apparatus 100 according to the present invention, when the structure thereof is designed, the optimal vibration mode can be determined in such a way that simulations are conducted in consideration of a variety of factors.
In detail, as shown in
As shown in the graph of
Meanwhile, as shown in
A target value of the vibration mode is the same 20.5 kHz. The simulation analysis was carried out to observe the variation in the vibration mode as the height h is increased to 50 mm, 60 mm and 70 mm.
When the height h of the extrusion die 110 was 50 mm, the value of the vibration mode was 20.5 kHz, which is the target value, but at 60 mm it was 19.8 kHz, and at 70 mm it was 18.7 kHz.
Furthermore, when the height h increased to 60 mm, the vibration mode was varied in such a way that the extrusion die shrunk inwards. When the height h was 70 mm, the vibration mode was varied in such a way that the extrusion die turned inside out.
As shown in
Here, a first-step hole of the first inner diameter part 142 that has a radius of 10 mm is fixed in size for extrusion. In this experiment, the simulation analysis was performed to observe variation in the vibration mode as the size of the hole of the second inner diameter part 144 varies.
According to the result of the simulations performed while the radius of the second inner diameter part 144 varies to 11.5 mm, 15.5 mm and 19.5 mm, the frequency of the vibration mode varied to 20.5 kHz, 19.8 kHz and 19.2 kHz. It can be understood that, compared to variation in the size of the hole, the variation in the vibration mode is less.
Furthermore, as shown in
Although it was expected that variation in the vibration mode would be comparatively large depending on the size of the front or rear conical surface 132 or 134, it was 20.7 kHz, that is, it was cot largely changed. Therefore, it was confirmed that the size of the front or rear conical surface 132 or 134 did not largely affect variation in the vibration mode.
As such, according to the result of simulations for the ultrasonic extrusion apparatus 100 of the present invention that were carried out in consideration of different kinds of factors, the vibration mode varied most significantly in accordance with the radius r of the extrusion die 110, and, to a lesser extent, in accordance with the height h of the extrusion die 110. It could be under stood that the radius of the extrusion hole 140 can be used to finely control the vibration mode.
As shown in
As can be understood from the result of the analysis, although vibrations are biased towards the center of the extrusion die 10, they are concentrated on opposite corners and a lower portion of the extrusion die 10. This means that vibrations generated by the ultrasonic vibrators 40 spread downward and sideways so that the vibrations are not reliably transmitted towards the center of the extrusion die 10.
Furthermore, in the conventional extrusion die 10, when vibrations are applied thereto, they must be concentrated on small holes formed on an upper end of the extrusion die 10 so as to reduce friction, thus reducing pressure by which an extrusion material must be pushed forwards. However, vibrations are concentrated just on the center of the extrusion die 10. Thus, when an actual extrusion process is conducted, the effect of the ultrasonic vibrators is reduced.
However, as shown in
Therefore, according to the result of the analysis of the ultrasonic extrusion apparatus 100 of the present invention, it is most important that the extrusion die 110 is designed such that the shape thereof is as balanced as possible. Furthermore, the size of the extrusion die 110 must be determined depending on the size of the extrusion die 110 and the number of vibrators.
In the ultrasonic extrusion apparatus 100 of the present invention having the above-mentioned construction, the front and rear conical surfaces 132 and 134 that are concave are respectively formed on the front and rear surfaces of the die body 130 which is disposed between the extrusion piston 120 and the die holder 122. In addition, the cylindrical jig 160 is provided on the front conical surface 132. Thereby, the extrusion pressure which is transmitted to the front surface of the die body 130 can be markedly reduced.
Furthermore, in the present invention, the vibration isolation unit 170 is installed between the rear conical surface 134 of the die body 130 and the die holder 122 so that vibrations which are transmitted from the die body 130 to the die holder 122 can be markedly reduced. Moreover, the six ultrasonic vibrators 150 which apply vibrations to the extrusion die 110 are arranged around the extrusion die 110 in the circumferential direction so that vibrations can be evenly applied to the entirety of extrusion die 110.
Therefore, vibrations which are generated from the ultrasonic vibrators 150 mounted to the extrusion die 110 can be effectively transmitted to the extrusion die 110. Thereby, when the extrusion process is conducted, friction between the extrusion die 110 and extrusion material can be minimized. As a result, compared to the conventional ultrasonic extrusion apparatus, high-density and high-quality metal products can be manufactured at a high production rate.
Although the preferred embodiment of the present invention has been disclosed for illustrative purposes, the present invention is not limited to such a special structure. Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. For example, although the number of chamfering surfaces 136 formed on the circumferential outer surface of the die body 130 has been illustrated as being six so that the six ultrasonic vibrators 150 are mounted to the respective chamfering surfaces 136 through the six corresponding mounting holes 138, the number of chamfering surfaces 136 or ultrasonic vibrators 150 may be changed, e.g., within a range from four to twelve. It should be understood that such simple design modifications or changes fall within the bounds of the present invention.
