JP2004351486A - Method and apparatus for manufacturing magnesium alloy plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a magnesium alloy plate wherein the magnesium alloy plate has an excellent formability in a plastic forming and is manufactured in the largest area ever manufactured and good productivity. <P>SOLUTION: In the method for manufacturing the magnesium alloy plate, following two processes are performed once or more, the same times respectively in that order; the first process to introduce the magnesium alloy plate 2 into a bending apparatus, to press the plate from the inlet side and pull the plate from the outlet side, to make the plate pass through the inlet and outlet at the same speed, and to bend the plate at a 0-90° inner angle in a plate thickness direction without changing the plate thickness; and the second process to bend the plate processed in the first process in the same way, but in the opposite direction of the plate thickness. By giving the plate shearing deformation like this, the magnesium alloy plate having the excellent formability is manufactured in the large area and good productivity. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for manufacturing a magnesium alloy sheet used for plastic working.
[0002]
[Prior art]
Among metal materials, magnesium alloys are lighter, have higher strength, have better vibration damping and workability, and have a relatively low melting point compared to other metals, so they require less energy for recycling. It has the characteristic that it is completed. Most of the magnesium alloy molded products are manufactured by a casting method such as die casting or injection molding. Since these molded articles have casting defects on the surface and inside, it is difficult to increase the coating yield, especially for exterior parts.
[0003]
On the other hand, in a molded product formed by pressing or the like, such surface defects are extremely reduced. However, since the magnesium alloy has a dense hexagonal crystal, the slip surface of deformation is small, and there is a difficulty in plastic workability such as rolling and bending. Therefore, press working using a magnesium alloy as a raw material is rarely practically used. Recently, magnesium alloys such as wrought materials (ASTM-standard AZ31 alloy) and special materials (ASTM-standard LA141 alloy) have been partially formed by forging or pressing. It has been reported that ductility appears on the surface of the material due to differences in metal structure such as crystal grain size and orientation and can be improved (see Non-Patent Document 1 by Yamanoi et al.).
[0004]
For example, the crystal grain size is reduced, or in the X-ray diffraction pattern, the diffraction intensity based on the presence of the (100) plane is weak and the diffraction intensity based on the presence of the (101) plane is increased. That is, by arranging the bottom (0001) plane (appearing as a plane equivalent to the (001) plane in the X-ray diffraction pattern) of the crystal in a direction inclined by 45 ° with respect to the tensile axis, the slip direction of the bottom and the maximum shear slip direction can be determined. The idea is to match them and improve the deformability. When the X-ray diffraction pattern is a material having a stronger diffraction intensity on the (101) plane than a plate material having a higher diffraction intensity on the (100) plane, the degree of freedom in the sliding direction is increased and the plastic workability at room temperature is improved. Are known. Further, as the crystal grain size becomes smaller, ductility is further improved. As a means for specifically realizing this, there is an ECAE (Equal-Channel-Angular-Extrusion) method. The magnesium alloy sheet produced by the ECAE method is described in detail in, for example, Non-Patent Document 2 of Mukai et al. The AZ31 alloy containing 3% by weight of aluminum and 1% by weight of zinc is subjected to 90 ° bending at 200 ° C. by the ECAE method, so that the diffraction intensity of the (101) plane becomes larger than that of the other planes. It is shown that a fine crystal structure of about 1 μm can be formed while the crystal grain size of the sheet material is usually 10 μm or more.
[0005]
FIG. 4 shows a configuration of an apparatus for performing a conventional lateral extrusion method for an aluminum alloy, that is, an ECAE method (see Patent Document 1). In FIG. 4, the aluminum alloy material 24 can be subjected to lateral shear deformation by inserting the aluminum alloy material 24 into one container 21 and extruding the aluminum alloy material 24 toward the next container or die 22 by the ram 23. . Thereby, the crystal grains can be refined by a very simple process. Further, when a magnesium alloy is used as the material for processing, the diffraction intensity of the (101) plane, which is preferable for workability, can be increased as described above.
Further, when a magnesium alloy is formed into a plate shape from a liquid or solid-liquid coexistence state and solidified while compressing in the plate thickness direction, a plate material having a high ratio of the (101) plane preferable for workability can be obtained (Patent Document 1) 2).
[0006]
[Non-patent document 1]
Abstract of 2000 Annual Meeting of the Japan Institute of Metals, 495 pages [Non-Patent Document 2]
Scripta Materialia, vol. 45 (2001), p. 89-94
[Patent Document 1]
JP-A-10-258334 (page 6, FIG. 1)
[Patent Document 2]
JP 2003-027173 A (page 7, FIG. 9)
[0007]
[Problems to be solved by the invention]
However, in the method shown in FIG. 4, the size and shape of a material that can be actually processed are limited to a round bar shape having a diameter of 20 mm and a length of about 100 mm. Therefore, it cannot be supplied in the form of a plate having a large area which is practically necessary, and the production cost is high due to low productivity.
In addition, the method of Patent Document 2 has a problem that if microscopic voids are introduced into the inside of the plate at the time of solidification, the ductility of the plate is likely to be reduced, and the apparatus also requires an expensive part for preventing combustion. .
[0008]
The present invention solves the above-mentioned conventional problems, and provides a magnesium alloy sheet having good formability in plastic working, in a large area that cannot be obtained conventionally, and a method of manufacturing a magnesium alloy sheet that can be manufactured with high productivity. Aim.
Another object of the present invention is to provide an apparatus for producing such a magnesium alloy sheet.
[0009]
[Means for Solving the Problems]
The present invention is to impart formability to a magnesium alloy sheet, and heats the magnesium alloy sheet to a temperature suitable for bending, guides the sheet into a bending apparatus, applies pressure from an inlet side and outlets. Applying a tension from the side, continuously passing the inlet and the outlet at the same speed, and bending the sheet in the sheet thickness direction at an angle of 0 ° or more and 90 ° or less without changing the sheet thickness; And performing the same bending process in the direction opposite to the plate thickness on the processed plate material in the order of one or more times in that order.
According to the present invention, a magnesium alloy sheet having good formability can be manufactured over a large area with high productivity.
[0010]
The magnesium alloy sheet used here is made of a Mg-Al-Zn-based alloy containing 2 to 10% by weight of aluminum and 0.5 to 1.0% by weight of zinc, and the bending temperature is preferably 180 to 300 ° C. ing.
It is preferable that the method further includes a step of performing an annealing treatment on the bent plate material. By this annealing treatment, the internal strain of the magnesium alloy sheet material is released, and the formability can be further improved.
The temperature of the annealing treatment is preferably higher than the above-mentioned processing temperature and not higher than the recrystallization end temperature of 360 ° C.
[0011]
The present invention comprises a device for continuously supplying a magnesium alloy plate material, a device for heating the plate material, and a bending portion that has a pressing mechanism and a tension mechanism on an inlet side and an outlet side, respectively, and that bends the plate material in the thickness direction. A first bending mechanism; a second bending mechanism having a pressing mechanism and a pulling mechanism on the inlet side and the outlet side, respectively, and including a bending portion configured to bend in a direction opposite to the first bending mechanism; The magnesium alloy sheet material heated by the heating apparatus is subjected to continuous bending in the sheet thickness direction, then bent in the opposite sheet thickness direction, and then collected. An apparatus for manufacturing an alloy sheet material is provided.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1
FIG. 1 shows a schematic configuration of an apparatus for manufacturing a magnesium alloy sheet according to the present embodiment. In FIG. 1, reference numeral 1 denotes a magnesium alloy sheet supply device configured by a roll around which the magnesium alloy sheet 2 is wound, and continuously supplies the magnesium alloy sheet 2. The movement path of the magnesium alloy sheet 2 fed from the supply device 1 includes a heating device 3a, a bending mold 4a, a pressing mechanism 5a and a tension mechanism 6a provided before and after the mold 4a, a heating device 3b, a bending metal A mold 4b, a pressing mechanism 5b and a tensioning mechanism 6b provided before and after the mold 4b, a heating device 3c, and a plate material collecting device 7 composed of a roll for winding the plate material are provided. 8a and 8b are heaters for heating the molds 4a and 4b, respectively.
[0013]
First, a magnesium alloy sheet 2 made of ASTM standard AZ31 alloy and having a thickness of 1 mm is heated to 200 ° C. while passing through a heating device 3a.
AZ31 is called a wrought material and is a material often used for press working. The principle of processing is the same as that of the conventional ECAE method for a bar, which is applied to a plate. In the case of the present alloy, the working temperature is required to be 180 ° C. or higher for improving the workability. However, if the temperature is too high, the introduced shear strain disappears due to diffusion, so that the working temperature is desirably 300 ° C. or lower.
[0014]
The heating device 3a may be, for example, a system such as radiation heating by a heater or another system. While maintaining the heating temperature, the plate material 2 is fed into the bending mold 4a by the pressing mechanism 5a composed of a pair of rolls. The bending mold 4a has a flow path with a gap equal to the thickness of the plate material 2 inside. This flow path is bent at a substantially right angle inside. When the thickness of the plate member 2 is 1 mm, the length of the flow path may be about 10 mm. If it is too long, the frictional resistance in the middle increases, and it becomes difficult to feed. At the same time that the plate material 2 is pushed into this flow channel, the plate material 2 is pulled out at the same speed as the pushing speed by the pulling mechanism 6a also composed of a pair of rolls.
[0015]
Although the optimum speed of the pressing into the bending mold changes depending on the processing temperature, in the present embodiment, the pressing was performed at 20 mm / sec. The condition width is desirably 3 to 100 mm / sec. If the processing speed is too low, shear deformation cannot be sufficiently caused. On the other hand, if the processing speed is too high, the plate material will break. By making the pushing speed and the pulling speed the same, the plate material 2 keeps the plate pressure constant, prevents deformation in the pulling direction, and can cause only shear deformation. In this case, if the tensile speed is made higher and the sheet material to be pulled out is controlled so as to apply a tensile stress of not more than the yield stress at the processing temperature, for example, 0 to 5 kg / mm ² , no tensile deformation occurs in the sheet material. , Only shear deformation can be given. In a state where there is no slippage at a bending angle, in order to cause a shearing deformation of 45 °, the bending may be performed at an inner angle of 90 °.
[0016]
When there is slippage at a corner or when a large distortion is desired, the bending angle may be reduced. However, if the inside angles are too small and the plate members interfere with each other, the plate members 2 themselves become obstacles to the continuous pulling of the plate members 2. The mold 4a is desirably heated by means such as a mold heater 8a so that the internal plate 2 is not cooled.
[0017]
Next, the plate material 2 is kept at a temperature of 200 ° C. by the heating mechanism 3b in the same procedure, and is pushed into the mold 4b by the roll of the pressing mechanism 5b, and is bent in the direction opposite to the thickness of the mold 4a while being pulled. Pull out by the mechanism 6b. The speed is also 100 mm / sec.
When the pair of bending in the thickness direction is performed a plurality of times, the plate member 2 is more reliably subjected to shear deformation. The drawn-out plate member 2 is again subjected to an annealing process of heating to 300 ° C. by the heating mechanism 3c. This process removes only internal distortion. The orientation caused by the shear deformation is maintained. After being tempered, it is taken up by a collecting device 7 which is a roll-shaped take-up device.
[0018]
The X-ray diffraction pattern of the AZ31 alloy has main diffraction peaks on the (100), (002) and (101) planes, and has (102), (110), (103) and (112) planes. The surface has a weak diffraction peak.
In the X-ray diffraction pattern of the plate 2 processed as described above, the ratio of the sum of the diffraction peaks of the (101) plane and the diffraction peak of the (110) plane to the total sum of the diffraction peaks of all the planes is about 46%. It is. This ratio is higher than 39% of the ratio occupied by the sum of the diffraction peak of the (100) plane and the diffraction peak of the (002) plane. This is because the plate material produced by the conventional normal rolling mainly has the (100) plane, whereas the crystal orientation is more preferable. In reality, the plane orientations are not completely aligned, and have a width of ± 0.5 ° or less. The average particle size is 5 μm, which is smaller than 10 μm or more for a normal rolled material.
[0019]
The higher the temperature of the tempering step and the longer the time, the larger the crystal grain size of the plate material 2 becomes. This refining step may be performed in a step different from the present system. In order to pass the plate 2 into the mold 4a, as shown in FIG. 2, the mold 4a is first opened in 41 and 42, and after passing the plate 2, both molds are closed. good. FIG. 2 shows that the mold 41 has a stepped portion 43 that engages the end of the mold 42, and a flow path 44 of the plate 2 is formed between the molds 41 and 42.
In the present embodiment, a plate made of an AST31 standard AZ31 alloy is used. However, it is needless to say that the present invention can be applied to a plate made of another magnesium alloy, for example, an AZ91 alloy having a high aluminum content of 9%. This AZ91 alloy is less deformable than the AZ31 alloy, but is excellent in corrosion resistance.
[0020]
Embodiment 2
The manufacturing apparatus according to the present embodiment will be described with reference to FIG.
FIG. 3 is an enlarged view of a roll-type bending mechanism of the apparatus for manufacturing a magnesium alloy sheet according to the present embodiment. The difference between the present embodiment and the first embodiment is that a roll mechanism is used as a bending mechanism. In FIG. 3, the inner peripheral roll 9 is fixed, and the plate material 2 is caused to travel by a plurality of outer peripheral drive rolls 10. The plate material 2 travels only at a small speed due to the friction of the fixed inner peripheral roll 9, whereas the outer peripheral side is pushed forward by the drive roll 10, so that the speed difference between the inner periphery and the outer periphery causes the plate material 2 to move forward. 2 undergoes shear deformation. The processing conditions such as the processing temperature and the feed speed of the plate 2 are the same as in the first embodiment.
[0021]
In the present embodiment, since the plate member 2 can be pushed forward by the outer peripheral drive roll 10, the plate member 2 can be inserted without increasing the interval between the inner peripheral roll 9 and the outer peripheral drive roll 10 of the bending mechanism. Has the effect of
In addition, the present embodiment can be applied to a plate material having a width of about 300 mm, which is usually used for manufacturing a rolled material, because the device configuration is close to the plate material, and it is possible to manufacture a plate material having a wider width and excellent workability. Can be.
[0022]
【The invention's effect】
As described above, according to the present invention, a magnesium alloy sheet having good formability in plastic working can be manufactured with a large area and high productivity which cannot be obtained conventionally.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a manufacturing apparatus of a magnesium alloy sheet according to Embodiment 1 of the present invention.
FIG. 2 is a schematic longitudinal sectional view of a mold showing a method of setting a plate material according to the first embodiment of the present invention.
FIG. 3 is a diagram illustrating a configuration of a roll-type bending mechanism according to a second embodiment of the present invention.
FIG. 4 is a schematic longitudinal sectional view showing a configuration of an apparatus for performing a conventional ECAE method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Continuous supply mechanism 2 Magnesium alloy plate material 3 Heating mechanism 4 Bending mold 5 Pressing mechanism 6 Pulling mechanism 7 Continuous recovery mechanism 8 Mold heater 9 Inner circumference roll 10 Outer circumference drive roll

Claims (4)

A plate material made of an Mg-Al-Zn-based alloy containing 2 to 10% by weight of aluminum and 0.1 to 1.0% by weight of zinc and heated to 180 to 300 ° C is guided into a bending device, and an inlet is provided. Apply pressure from the side and apply tension from the outlet side, continuously pass through the inlet and outlet at the same speed, and bend in the thickness direction at an angle of 0 ° or more and 90 ° or less without changing the thickness. Magnesium, wherein the step of processing and the step of applying the same bending process to the processed plate material in the opposite direction of the plate thickness are performed at least once and the same number of times in this order. Manufacturing method of alloy sheet material. The method for producing a magnesium alloy sheet according to claim 1, further comprising a step of performing an annealing treatment on the bent sheet. A first bending device including a device for continuously supplying a magnesium alloy plate material, a device for heating the plate material, and a bending portion having a pressing mechanism and a tension mechanism on an inlet side and an outlet side, respectively, for bending the plate material in the thickness direction. A mechanism, a second bending mechanism having a pressing mechanism and a pulling mechanism on the inlet side and the outlet side, respectively, and including a bending portion configured to bend in a direction opposite to the first bending mechanism, and an apparatus for continuously collecting the plate material. Manufacturing a magnesium alloy sheet material comprising: continuously bending the magnesium alloy sheet material heated by the heating device in a sheet thickness direction, then bending the sheet in an opposite sheet thickness direction, and collecting the magnesium alloy sheet material. apparatus. 4. The apparatus for manufacturing a magnesium alloy sheet according to claim 3, wherein a bending angle of the bent portion is an inner angle of 0 ° or more and 90 ° or less, and a plate thickness in the bent portion is constant.

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