JP5942573B2 - Magnesium alloy plate manufacturing method - Google Patents

Description

  The present invention relates to a method for producing a magnesium alloy plate and a magnesium alloy plate. In particular, the present invention relates to a method for producing a magnesium alloy plate that can produce a magnesium alloy plate having excellent surface properties and excellent formability with high productivity.

  Magnesium (hereinafter referred to as Mg) alloy has excellent characteristics such as light weight and high specific strength, so that it can be used for portable electrical and electronic equipment such as mobile phones and notebook personal computers, as well as aircraft and automobile parts. It is used for various members. The Mg alloy plate used as the material of these Mg alloy members is manufactured, for example, by rolling a material plate (for example, a cast material) made of an Mg alloy. As an apparatus used for the rolling process, for example, there is one shown in Patent Document 1.

  The rolling mill of Patent Document 1 includes a pair of coilers (reels), a pair of heat boxes that store the respective coils, a rolling roll that is disposed between the pair of coils (heat box), and each of the coilers and the rolling rolls. It comprises a pinch roller (pinch roll) provided between them. The coiler includes a winding drum that winds a long metal plate (for example, a Mg alloy material plate) and winds and feeds the material plate. The heat box heats the material plate to a predetermined temperature for each coiler. The pinch roller supports the material plate sandwiched from the front and back of the material plate, and is maintained at a predetermined temperature by heating means provided on the pinch roller itself, and maintains the material plate at a predetermined temperature during the rolling process. The rolling roll is controlled to a predetermined temperature by a heating means provided on the rolling roll itself, and is plastically processed to a predetermined thickness with a material plate fed out from a feeding-side coiler interposed therebetween.

  In this rolling mill, the material plate is fed out from one coiler, passes in the order of one pinch roller → rolling roll → the other pinch roller, and is wound around the other coiler. Then, the wound material plate is unwound and fed out, passes through the other pinch roller → rolling roll → one pinch roller in this order, and is wound by one coiler. In this way, by rotating the material plates in a reciprocating manner while reversing the rotation directions of both the coilers for each pass, the material plates are rolled in a plurality of passes to produce Mg alloy plates.

  Since this pinch roller is provided with a heating means as described above, a temperature drop caused by exposure of the material plate to the atmosphere between both the coiler and the rolling roll by bringing the pinch roller maintained at a predetermined temperature into contact with the material plate. Can be suppressed. Therefore, it is possible to perform rolling while controlling the material plate to a desired temperature, and it is possible to prevent the edge crack of the material plate due to the temperature of the material plate being too low and the burning of the surface due to the temperature of the material plate being too high. In addition to being able to suppress, it is possible to sufficiently impart processing strain and form a fine crystal structure. That is, according to this rolling mill, it is possible to produce an Mg alloy plate having excellent surface properties and formability.

JP 2011-2000889 A

  In recent years, improvement in the productivity of Mg alloy sheets is desired as the demand for Mg alloy sheets increases. As a measure for improving productivity, rolling is performed by increasing the travel speed of the material plate. Since Mg alloy has poor plastic workability at room temperature, it is necessary to perform rolling in a heated state. When attempting to improve the productivity of Mg alloy sheets by increasing the running speed, the material sheet is exposed to the atmosphere during the rolling process. The time is shortened and the temperature drop of the blank is suppressed. For this reason, when a plurality of passes are rolled by the reciprocating rolling, heat is accumulated in the material plate every time the rolling is performed, and the temperature of the material plate may increase. As a result, the lubricant adhering to the surface of the material plate, particularly the material plate, is burned and slippage is deteriorated, and the material plate is stretched or cross-flowed. In addition, sufficient work strain is not accumulated and the crystal structure is difficult to become fine, so that the plastic workability becomes poor.

  The present invention has been made in view of the above circumstances, and one of its purposes is to provide a method for producing an Mg alloy plate capable of producing an Mg alloy plate having excellent surface properties and excellent formability with high productivity. There is.

  Another object of the present invention is to provide an Mg alloy plate produced by the above production method.

  The method for producing an Mg alloy plate of the present invention is a method for producing an Mg alloy plate by subjecting a material plate made of a magnesium alloy to reciprocating travel so as to subject the material plate to rolling in a plurality of passes. Specifically, an unwinding step of unwinding the material plate wound in a coil shape, a rolling step of rolling the unrolled material plate with a rolling roll, and a winding of winding the rolled material plate in a coil shape And at least the rolling process is performed on the heated material plate. Then, after the winding process, the wound material plate is again fed out to the rolling roll. In this manufacturing method, at least one of the plurality of passes is performed at a high speed of 40 m / min or more for the travel speed of the material plate. A cooling process for cooling the material plate during the high-speed traveling is provided, and the temperature of the material plate is set to 280 ° C. or lower throughout the entire path by the cooling process.

  The manufacturing method of Mg alloy board of this invention can manufacture Mg alloy board which is excellent in surface property and excellent in formability with high productivity. Even if at least one of the rolling passes is performed at high speed, the temperature of the material plate can be controlled to a desired temperature over all passes by cooling the material plate. For this reason, it is possible to suppress the temperature of the material plate from becoming excessively high, so that it is possible to suppress the burning of the surface, and it is possible to impart sufficient processing strain, so that the crystal structure can be made fine.

  As one form of this invention manufacturing method, it is mentioned that a cooling process is performed at least between a rolling process and a winding process.

  According to said structure, a raw material board can be effectively controlled to desired temperature by performing a cooling process between the rolling process and winding process which are easy to raise the temperature of a raw material board in each process, ie, a rolling process. .

  As one form of this invention manufacturing method, a pinch roll whose surface temperature is 20 degreeC or more and 180 degrees C or less is mentioned to a raw material board at a cooling process.

  According to said structure, since the pinch roll of the said temperature is made to contact, a raw material body can be cooled effectively and the temperature of a raw material board can be controlled effectively.

  As one form of the manufacturing method of the present invention, when the cooling step is performed at least between the rolling step and the winding step, the raw material plate is kept warm between the feeding step and the rolling step during high speed running, and the rolling step One example is not keeping the material plate warm during the winding process.

  According to said structure, a raw material board can be rolled at the temperature suitable for rolling by heat-maintaining a raw material board by the delivery side. And it can suppress that the temperature of a raw material board becomes high too much by cooling a raw material board on the winding side, without heat retention.

  As one form of the manufacturing method of the present invention, it is possible to keep the material plate warm at least one of the steps during traveling at a low speed of less than 40 m / min.

  According to the above configuration, during the low-speed traveling, for example, the acceleration (deceleration) process from the start of travel (high speed travel) to the high speed travel (travel stop) of the material plate is caused by the exposure of the material plate to the atmosphere. Since it is easy to dissipate heat and the temperature of the material plate is likely to decrease, the material plate can be controlled to a desired temperature by keeping warm.

  As one form of this invention manufacturing method, using the rolling apparatus provided with the pinch roll for heat retention and the pinch roll for cooling in each before and behind a roll is mentioned. In that case, the warming and cooling pinches are placed before and after the rolling roll so that the warming plate is kept warm by the pinching roll for heat retention before the rolling process and the raw sheet is cooled by the pinching roll for cooling after the rolling process. The roll is switched between forward traveling and backward traveling.

  According to the above configuration, the material plate can be kept warm on the feeding side and the material plate can be cooled on the take-up side regardless of whether the vehicle travels in the outward path or the return path. Therefore, the same temperature control can be performed in the forward travel and the backward travel, and the material plate can be easily controlled to a desired temperature.

  As one form of this invention manufacturing method, it is mentioned that content of Al in Mg alloy is 7 mass% or more and 12 mass% or less.

  According to said structure, Mg alloy board excellent in corrosion resistance and a mechanical characteristic can be manufactured because Al contains in said range.

  The Mg alloy plate of the present invention is obtained by the above-described method for producing an Mg alloy plate of the present invention.

  The Mg alloy sheet of the present invention has excellent surface properties and excellent formability. This is because the Mg alloy plate can be controlled to a desired temperature during production, and the temperature of the material plate can be prevented from excessively rising. Moreover, because sufficient processing strain can be imparted, the crystal grain size can be made fine. A molded product obtained by subjecting this Mg alloy plate to plastic working such as press working has few defects such as cracks and is of high quality.

  The method for producing an Mg alloy plate of the present invention can produce an Mg alloy plate having excellent surface properties and excellent formability with high productivity.

  The Mg alloy sheet of the present invention has excellent surface properties and excellent formability.

It is a schematic block diagram of the rolling device used in the embodiment.

  Embodiments of the present invention will be described below.

<< Manufacturing method of magnesium alloy sheet >>
The method for producing an Mg alloy plate according to the present invention is a method for producing an Mg alloy plate by rolling a material plate made of an Mg alloy to the material plate by reciprocating traveling. Specifically, an unwinding step of unwinding a material plate wound in a coil shape, a rolling step of rolling the unrolled material plate with a rolling roll, and a winding step of winding the rolled material plate into a coil shape And at least the rolling process is performed on the heated material plate. And after the said winding process, the wound raw material board is again let out to a rolling roll. The manufacturing method is characterized in that at least one of the plurality of passes is performed at a high speed of a material plate traveling speed of 40 m / min or more, and includes a cooling process for cooling the material plate during high speed traveling. It is in the point which makes the temperature of a raw material board 280 degrees C or less over all the passes by a point and a cooling process. Hereinafter, in describing in detail, an example of an apparatus for manufacturing an Mg alloy plate will be described first with reference to FIG. 1, and then a constituent material of the Mg alloy plate and the above-described steps will be described in this order.

[Rolling equipment]
As an apparatus to utilize, the rolling apparatus 100 which built the rolling line as shown in FIG. 1 is mentioned, for example. The rolling lines are arranged so as to be spaced apart from each other so as to sandwich a pair of reversible reels 10a and 10b and a pair of reels 10a and 10b and a material plate 1 made of a traveling Mg alloy. A pair of rolling rolls 3. The coil-shaped material plate 1 is installed on one reel 10a and rewinded, and one end of the material plate 1 is taken up by the other reel 10b, so that the material plate 1 travels between the reels 10a and 10b. During travel, the material plate 1 can be rolled by being sandwiched between the rolling rolls 3. In the example shown in FIG. 1, the reels 10a and 10b are housed in heat boxes 2a and 2b, respectively, and the material plate 1 wound around the reels 10a and 10b can be heated by the heat boxes 2a and 2b. The heated material plate 1 is unwound from one reel 10a, fed out, discharged from one heat box 2a, travels toward the other heat box 2b, and is wound around the other reel 10b. The rolling apparatus 100 can perform reverse rolling by reversing the rotation direction of the reels 10a and 10b for each pass. In addition, in FIG. 1, the number of the rolling rolls 3 is an illustration, and it can be set as the structure which has arrange | positioned several pairs of rolling rolls in the running direction of the raw material board 1. FIG.

  The rolling device 100 further includes a pinch roll 4 between each of the heat boxes 2 a and 2 b and the rolling roll 3. The pinch rolls 4 are arranged on the front and back of the material plate 1 to apply a certain tension to the material plate 1 and guide the material plate 1 to the rolling roll 3 and the heat boxes 2a and 2b. Furthermore, as a function of the pinch roll 4, it is possible to keep the temperature so that the temperature of the material plate 1 does not decrease, or to cool the material plate 1 so that the temperature of the material plate 1 does not increase too much. In the case of heat insulation, for example, the heating can be controlled to a predetermined temperature by providing the roll itself with a heating means such as a heater. In the case of cooling, for example, it is possible to control the cooling to a predetermined temperature by providing a cooling means for circulating a liquid refrigerant such as water in the roll.

  The number of pinch rolls 4 disposed between each of the above can be selected as appropriate. In the case where a plurality of pairs of pinch rolls 4 are arranged between each of the above, it is preferable that at least one pin is a heat-retaining pinch roll 4ah (4bh) and at least one pin is a cooling pinch roll 4ac (4bc). Here, two pairs of pinch rolls 4 are arranged in parallel in the running direction of the blank plate 1 between each of the above. Between each of the above, one pinch roll 4ah (4bh) is used for heat insulation for keeping the material plate 1 warm, and the other pinch roll 4ac (4bc) is used for cooling for cooling the material plate 1. In addition, between each said, you may arrange | position multiple pinch rolls 4ah (4bh) for heat retention, and pinch roll 4ac (4bc) for cooling in a running direction, respectively. In particular, if a plurality of cooling pinch rolls 4ac (4bc) are arranged in parallel on the winding side between the above, it is easy to reliably maintain the temperature of the material plate 1 at 280 ° C. or lower.

  The arrangement form of the plurality of pairs of pinch rolls 4 can be selected as appropriate. Either the pinch roll 4ac (4bc) for cooling or the pinch roll 4ah (4bh) for heat insulation may be on the heat box 2a (2b) (rolling roll 3) side. For example, the cooling pinch roll 4ac (4bc) (the heat-retaining pinch roll 4ah (4bh)) is arranged on the rolling roll 3 side on the one side between the above, and the cooling pinch roll on the other side between the above. 4bc (4ac) (insulating pinch roll 4bh (4ah)) may be arranged on the heat box 2b (2a) side. Here, between each of the above, the cooling pinch roll 4ac (4bc) is disposed on the rolling roll 3 side, and the heat retaining pinch roll 4ah (4bh) is disposed on the heat box 2a (2b) side.

  It is preferable that the pinch roll 4 used between each of the above is switched between the respective ones according to the traveling speed of the material plate 1. Specifically, during traveling at a high speed of 40 m / min or more, the material plate 1 travels from the left (right) side to the right (left) side in FIG. When the forward direction (return path) is set, on the feeding side (the left (right) side of the rolling roll 3), the heat-insulating pinch roll 4ah (4bh) is brought into contact with the material plate 1 to cool the pinch roll 4ac (4bc) for cooling. Are separated from each other in the vertical direction of the paper so as not to contact the material plate 1. On the other hand, on the winding side (the right (left) side of the roll 3), the pinch roll 4bc (4ac) for cooling is brought into contact with the material plate 1, and the pinch roll 4bh (4ah) for heat insulation is made to be the material plate 1. It is possible to keep them apart in the vertical direction of the paper so that they do not come into contact with each other.

  In this way, during high-speed running, the feeding side is switched to the heat-retaining pinch roll 4ah (4bh), and the winding side is switched between the forward direction and the backward direction so as to be the cooling pinch roll 4bc (4ac). Is preferred. By doing so, since the material plate 1 can be kept warm on the feeding side and the material plate 1 can be cooled on the take-up side in both the outward travel and the backward travel, the temperature control of the material plate 1 is the same on the outward path and the return path. it can. Therefore, it is easy to control the temperature of the material plate 1 to a desired temperature.

  On the other hand, during traveling at a low traveling speed of the material plate 1 of less than 40 m / min, the both sides of the feeding side and the winding side are used for heat insulation regardless of whether the rolling direction is the forward direction or the backward direction in the figure. The pinch rolls 4ah and 4bh are preferably brought into contact with the material plate 1. By doing so, the temperature of the material plate 1 can be controlled to a desired temperature even during low-speed traveling in which the temperature of the material plate 1 is likely to decrease, and an excessive decrease in temperature can be suppressed. It should be noted that the cooling pinch roll 4ac (4bc) is not brought into contact with the material plate 1 on the feeding side, and may or may not be brought into contact on the winding side.

  In this way, it is preferable to switch the pinch rolls used during high speed running and low speed running.

  The rolling device 100 preferably includes a temperature sensor (not shown) for measuring the temperature of the blank 1. Here, the measurement points of the temperature of the blank 1 in the traveling direction are provided between the heat box 2a (2b) and the pinch roll 4ah (4bh) and between the pinch roll 4ac (4bc) and the rolling roll 3, respectively. . That is, the point A immediately after the material plate 1 exits the heat box 2a (2b), the point B immediately before passing through the rolling roll 3, the point C immediately after, and the point D immediately before entering the heat box 2b (2a). There are four places. In each of the points A to D, it is possible to measure the center temperature in the width direction of the blank 1. The type of temperature sensor may be a contact type sensor or a non-contact type sensor. In particular, a non-contact sensor is preferable in order to prevent wrinkles.

  In addition, it is preferable to provide a temperature sensor for measuring the temperature of the rolling roll 3 and the pinch roll 4. The temperature measurement location may be the center in the width direction of both the rolling roll 3 and the pinch roll 4. The type of the temperature sensor that measures the temperature of the rolling roll 3 and the pinch roll 4 may be a contact type sensor or a non-contact type sensor.

  What is necessary is just to change suitably the temperature of the rolling roll 3 or the pinch roll 4 based on the temperature of the raw material board 1 measured with the temperature sensor. Specifically, when the rolling direction is the forward (return) direction, based on the temperature measured at the point A, when the temperature of the blank 1 is lower (higher) than the desired temperature, the heat retaining pinch roll 4ah ( It is good to raise (lower) the temperature of 4bh). Based on the temperature measured at the point B, when the temperature of the blank 1 is lower (higher) than the desired temperature, the temperature of the rolling roll 3 may be raised (lowered). If the temperature of the blank 1 is lower (higher) than the desired temperature based on the temperature measured at the point C, the temperature of the cooling pinch roll may be raised (lowered). If the temperature of the material plate 1 is lower (higher) than the desired temperature following the temperature measured at the point D, the temperature of the heat box 2b may be raised (lowered). If it does so, it will become easy to control the raw material board 1 to desired temperature (280 degrees C or less).

[Magnesium alloy]
Next, in manufacturing the Mg alloy plate, the Mg alloy to be prepared includes various compositions having the Mg element as a main component and containing the additive element in the Mg (remainder: inevitable impurities). In particular, in the present invention, it is preferable to use an Mg—Al alloy containing at least aluminum (Al) as an additive element. The greater the Al content, the better the corrosion resistance as well as the mechanical properties such as strength and plastic deformation resistance. Therefore, in the present invention, it is preferable to contain 3% by mass or more of Al, more preferably 5% by mass or more, more preferably 7.0% by mass or more, and even more preferably 7.3% by mass or more. However, if the Al content exceeds 12% by mass, the plastic workability is lowered, so the upper limit is 12% by mass. The Al content is particularly preferably 11% by mass or less, and more preferably 8.3% by mass to 9.5% by mass.

  Additive elements other than Al include zinc (Zn), manganese (Mn), silicon (Si), beryllium (Be), calcium (Ca), strontium (Sr), yttrium (Y), copper (Cu), silver ( One or more selected from Ag), tin (Sn), nickel (Ni), gold (Au), lithium (Li), zirconium (Zr), cerium (Ce), and rare earth elements RE (excluding Y and Ce) These elements are mentioned. When such elements are included, the total content is 0.01% by mass or more and 10% by mass or less, preferably 0.1% by mass or more and 5% by mass or less. Among these additive elements, at least one element selected from Si, Sn, Y, Ce, Ca, and rare earth elements RE (excluding Y and Ce) is added in a total amount of 0.001% by mass or more, preferably a total of 0.001%. When the content is 1% by mass or more and 5% by mass or less, heat resistance and flame retardancy are excellent. When the rare earth element is contained, the total content is preferably 0.1% by mass or more, and particularly when Y is contained, the content is preferably 0.5% by mass or more. Examples of the impurities include Fe.

  More specific compositions of Mg-Al alloys include, for example, AZ-based alloys (Mg-Al-Zn-based alloys, Zn: 0.2 mass% to 1.5 mass%) in ASTM standards, AM-based alloys (Mg -Al-Mn alloy, Mn: 0.15 mass% to 0.5 mass%), AS alloy (Mg-Al-Si alloy, Si: 0.3 mass% to 4.0 mass%), Mg -Al-RE (rare earth element) based alloy, AX based alloy (Mg-Al-Ca based alloy, Ca: 0.2 mass% to 6.0 mass%), AJ based alloy (Mg-Al-Sr based alloy, Sr: 0.2% by mass to 7.0% by mass). In particular, Mg—Al based alloys, typically AZ91 alloy, containing Al from 8.3 mass% to 9.5 mass% and Zn from 0.5 mass% to 1.5 mass% have corrosion resistance and mechanical properties. It is excellent and preferable.

〔Manufacturing process〕
Next, the manufacturing method of this invention is demonstrated using the rolling apparatus 100 mentioned above. First, a material plate 1 made of an Mg alloy is prepared. Subsequently, after the material plate 1 is preheated to a desired temperature, the material plate 1 is reciprocated to perform multiple passes of rolling. Here, at least one of the plurality of passes is performed at a high speed of 40 m / min. Of course, all passes may be performed at high speed.

[Preparation of material board]
(casting)
A material plate 1 made of Mg alloy is prepared. For the material plate 1, a cast material (cast plate) having the above-described composition can be suitably used. The cast material may be manufactured by a continuous casting method such as a twin roll casting method or die casting, and may be manufactured by a known method such as a manufacturing method described in WO / 2006/003899.

(Solution treatment)
Although the cast material may be rolled, the solution material obtained by subjecting the cast material before rolling to solution treatment may be used as the material plate 1. The cast material can be homogenized by solution treatment. The conditions for the solution treatment include holding temperature: 350 ° C. or higher, preferably 380 ° C. to 420 ° C., holding time: 30 minutes to 2400 minutes. It is preferable to increase the holding time as the Al content increases. Moreover, in the cooling from the holding time, if the cooling rate is increased by using forced cooling such as water cooling or blast, the precipitation of coarse precipitates can be suppressed and a plate material having excellent rolling properties can be obtained. . When the solution treatment is performed on a long cast material, it can be efficiently heated if the cast material is wound into a coil shape like the above-described cast coil material.

[Preheating process]
In rolling the material plate 1, in order to improve the plastic workability (rollability) of the material plate 1, preheating is mentioned. Specifically, the material plate 1 is heated so that the temperature (reference temperature) is 280 ° C. or less. The set temperature of the heating means such as the heat box 2a (2b) can be selected within a range of 280 ° C. or less. In particular, in the material plate 1, the temperature immediately before rolling is 200 ° C. or more and 250 ° C. or less over all passes. In addition, it is preferable to adjust the set temperature. The heating time may be appropriately set according to the weight, size (width, thickness), number of turns, and the like of the coil. Here, the raw material plate 1 wound up in a coil shape is installed in the heat box 2a (2b) described above and heated. In addition, after the coil-shaped raw material board 1 is heated to predetermined temperature with the heating furnace which is not illustrated, you may make it install in a heat box.

[Feeding process]
The material plate 1 wound up in a coil shape is fed from the reel 10a (10b) to the rolling roll 3.

[Rolling process]
The fed material plate 1 is rolled by a rolling roll 3.

  Specifically, heating is performed so that the surface temperature of the rolling roll 3 is in a range of 200 ° C. or more and 250 ° C. or less. By setting the surface temperature of the rolling roll 3 to 200 ° C. or higher, the material plate 1 can be maintained in a sufficiently heated state, so that the material plate 1 can be in a state excellent in plastic workability and can be rolled well. By setting the surface temperature of the rolling roll 3 to 250 ° C. or less, even if the temperature of the material plate 1 rises due to processing heat generated when rolling, the surface of the material plate 1 is not burned. It is possible to manufacture a rolled plate excellent in plastic workability by suppressing the coarsening of the crystal grain size and release of processing strain introduced by rolling.

  In rolling in each pass, the rolling reduction per pass can be appropriately selected. The rolling reduction per pass is preferably 10% to 40%, and the total rolling reduction is preferably 75% to 85%. By applying multiple (multi-pass) roll rolling to the material at such a reduction rate, the desired thickness can be achieved, the average crystal grain size can be reduced, plastic workability can be improved, and defects such as surface cracks can be achieved. Can be suppressed.

  In rolling, it is preferable to use a lubricant because the friction between the rolling roll 3 and the material plate 1 can be reduced and rolling can be performed satisfactorily. The lubricant may be appropriately applied to the rolling roll 3. It is preferable to use a lubricant in which the deteriorated layer is not formed at about 300 ° C. in consideration of the maximum value of the heating temperature of the rolling roll: 290 ° C. and a margin. If it does so, it will be hard to produce oil burning etc. on the surface of the raw material board 1, it will become easy to roll uniformly in the width direction, and the narrowing of the raw material board 1, a half-stretching, a transverse flow, meandering, winding deviation, etc. can be suppressed. The narrowing down means that a part of the material plate 1 in the width direction is folded when the material plate 1 enters the rolling roll 3, and a dent mark may be generated in the material plate 1 on the exit side of the rolling roll 3. . The half stretch means that the stretch in the rolling direction of the material plate 1 is partially loosened due to the difference in the width direction. The transverse flow means that the material plate 1 is shifted to one side in the width direction with respect to the rolling direction. The meandering means that the width of the material plate 1 does not substantially change, and the material plate 1 moves to or from both sides in the width direction with respect to the rolling direction. Winding deviation means that the turns of the material plate wound in a coil shape by cross flow or meandering are displaced from each other in the coil width direction, and the width of the coil becomes larger than the width of the material plate 1.

  In order to prevent the lubricant and the altered layer from locally existing on the material plate 1, it is preferable to level the lubricant on the surface of the material plate 1 immediately before supplying the material plate 1 to the rolling roll 3. For example, a leveling means such as a brush or a wiper may be arranged upstream of the rolling roll 3 to make the unevenness of the lubricant on the surface of the material uniform.

[Winding process]
The rolled material plate 1 is wound up on a reel 10b (10a).

  And the running direction of the raw material board 1 is reversed, and these each process is repeated. Specifically, the wound raw material plate 1 is again fed out to the rolling roll 3, and the raw material plate 1 is reciprocated to perform a plurality of passes of rolling on the raw material plate 1.

[Cooling process]
In the manufacturing method of the present invention, the material plate 1 is cooled while the material plate 1 is traveling at high speed.

  The portion to be cooled is preferably at least after the rolling step in which the temperature of the blank 1 is likely to be high in each step, that is, from the rolling roll 3 to the reel 10b (10a) on the winding side. If it does so, the temperature of the raw material board 1 can be effectively maintained at 280 degrees C or less even during high-speed driving.

  By cooling the material plate 1, the temperature of the material plate 1 is maintained at 280 ° C. or lower over the entire pass. If rolling of a plurality of passes is performed at high speed as in this example, the temperature of the material plate 1 that has risen due to processing heat is unlikely to decrease. Therefore, when the material plate 1 is not cooled, the temperature of the material plate 1 is 280 ° C. In some cases, the temperature may be 350 ° C. or higher depending on the traveling speed. This is because, by traveling at high speed, the exposure time of the material plate 1 to the atmosphere is short, and it is difficult to dissipate heat. In that case, the surface of the raw material plate 1 is burnt and slipping is worsened, so that the raw material plate 1 is narrowed down and stretched, cross-flowed, unwinded, and the like. In addition, since the processing strain cannot be imparted sufficiently, the crystal structure cannot be made fine, and the Mg alloy plate excellent in plastic workability cannot be obtained. As for the minimum of the temperature of the raw material board 1, about 200 degreeC is preferable. By setting the temperature of the material plate 1 to 200 ° C. or higher, the material plate 1 can be maintained in a sufficiently heated state, and therefore, cracking of the material plate 1 due to the temperature of the material plate 1 being too low during rolling is suppressed. it can.

  The means for maintaining the material plate 1 at the above temperature is not particularly limited. For example, a fluid refrigerant such as cold air may be blown, or a solid cooling member such as a pinch roll may be contacted. Here, it cools by making it directly contact with the raw material board 1 with the pinch roll 4bc (4ac) for cooling mentioned above. By directly contacting the pinch roll 4bc (4ac), it becomes easy to control to a desired temperature. Specifically, the surface temperature of the cooling pinch roll 4bc (4ac) is preferably 20 ° C. or higher and 180 ° C. or lower. If it does so, the raw material board 1 can be cooled effectively. This surface temperature is particularly preferably 100 ° C. or lower. If it does so, even when the contact length of the pinch roll 4bc (4ac) for cooling and the raw material board 1 is short, it can fully control to desired temperature. At this time, the heat-insulating pinch roll 4bh (4ah) on the winding side of the rolling roll 3 is brought into a non-contact state with the material plate 1.

[Other processes]
Before the rolling process, that is, between the reel 10a (10b) and the rolling roll 3 on the feeding side, a heat retaining process for retaining the material plate 1 may or may not be performed. For example, when the heat retaining step is performed, the above-described heat retaining pinch roll 4ah (4bh) is brought into contact with the material plate 1 and the cooling pinch roll 4ac (4bc) is brought into a non-contact state with the material plate 1. If it does so, while being able to suppress the temperature fall of the raw material board 1 by the contact with the pinch roll 4, the temperature fall of the raw material board 1 can be suppressed before the raw material board 1 reaches the rolling roll 3 from the reel 10a (10b). Specifically, the temperature of the pinch roll 4ah (4bh) for heat retention is preferably heated to about 200 ° C to 250 ° C.

(When driving at low speed)
When traveling at a low speed of less than 40 m / min, it is preferable to perform the heat retaining step. Specifically, when the material plate 1 is accelerated (during the start of feeding the material plate 1 until it reaches high speed travel), and when the material plate 1 is decelerated (just before the end of winding the material plate 1), it travels at a low speed. Often. Therefore, at the time of acceleration and deceleration, the temperature of the material plate 1 is likely to decrease, and it is preferable to perform the above-described heat retaining process at least at one time, particularly both at the time of acceleration / deceleration. In addition, during the low-speed driving | running | working, the raw material board 1 may be cooled and does not need to be cooled. However, it is preferable not to cool the blank 1 between the reel 10a (10b) and the rolling roll 3 on the feeding side.

  Then, when the material plate 1 is taken up by the reel 10b (10a) after the cooling step and is rewound again and the material plate 1 is fed out to the rolling roll 3, between the reel 10b (10a) and the rolling roll 3, The pinch roll 4bc (4ac) is separated in the vertical direction on the paper surface so as not to contact the material plate 1. Here, when the material plate 1 is kept warm as described above, the heat-insulating pinch roll 4bh (4ah) may be disposed so as to contact the material plate 1. Similarly, between the rolling roll 3 and the reel 10a (10b), the heat-retaining roll 4ah (4bh) is separated in the vertical direction on the paper surface so as not to contact the material plate 1, and the pinch roll 4ac (4bc) for cooling is separated. Is placed in contact with the blank 1. By doing so, the raw material board 1 rolled as mentioned above can be cooled.

  In this way, the raw material plate 1 is changed by switching the forward side and the backward direction so that the feeding side is the heat-insulating pinch roll 4ah (4bh) and the winding side is the cooling pinch roll 4bc (4ac). Even when reciprocating, the material plate 1 can always be kept warm on the feeding side, the material plate 1 can be cooled on the winding side, and the same temperature control can be performed on the forward path and the return path. Easy to control.

  Thus, when each step is repeated, when the temperature of the material plate 1 preheated in the preheating process at the start of manufacture is set as the reference temperature, the temperature of the material plate 1 does not exceed 280 ° C. over the entire pass, and the reference temperature It is preferable to produce so that it may become less than +/- 50 degreeC. In particular, it is preferable to manufacture so that the temperature of the material plate 1 is within ± 30 ° C. of the reference temperature in each pass. If it does so, while being able to prevent the raw material board 1 from being burned, crystal structure can be made fine.

(Final winding process)
A series of steps of the preheating step, the feeding step, the rolling step, and the winding step are continuously repeated, and after rolling the desired number of times, the obtained rolled plate (Mg alloy plate) is finally coiled Wind in shape. The Mg alloy plate has a structure in which processing strain (shear band) introduced by rolling exists. Therefore, the Mg alloy plate exhibits dynamic recrystallization during plastic processing such as press processing, and is excellent in plastic workability. In particular, when rolling at the final pass rolling, the temperature of the rolled plate immediately before winding is not recrystallized, specifically 150 ° C. or lower, and the Mg alloy plate having excellent flatness is obtained. It can be set as the structure | tissue where distortion remains enough. In order to obtain a temperature at which the rolled plate immediately before winding is not recrystallized, the travel speed of the blank plate 1 may be adjusted. However, when the rolled plate is cooled by forced cooling such as blast, the temperature is brought to a predetermined temperature in a short time. It is excellent in workability.

(Correction process after production)
The coil material wound up after rolling can be used as a product (typically, a material of Mg alloy material such as plastic working material) as it is. Furthermore, the coil material can be rewound to give a predetermined bending to the rolled plate, and the processing distortion introduced by rolling can be corrected. For the correction, for example, a roller leveler in which a plurality of rollers are arranged in a staggered manner, and a rolled plate is passed between the rollers to repeatedly bend the rolled plate can be suitably used. By performing such correction, it is possible to obtain an Mg alloy plate that is further excellent in flatness, and because the processing strain is sufficiently present, the plastic workability is excellent. If the roller is provided with a heating means, for example, a heater, and the temperature of the roller is heated to 100 ° C. or more and 300 ° C. or less to provide warm correction, cracking or the like hardly occurs. A magnesium alloy plate (rolled plate) as a raw material may be heated in advance before correction. Specific heating temperature is 100 ° C. or higher and 250 ° C. or lower, preferably 200 ° C. or higher. The Mg alloy plate that has undergone the straightening process can be used as a product (typically a material of an Mg alloy material such as a plastic working material) as it is. Furthermore, in order to improve the surface condition, surface polishing may be performed using a polishing belt or the like.

<Effect>
According to the Mg alloy plate manufacturing method described above, an Mg alloy plate excellent in surface properties and formability can be manufactured with high productivity. By providing a cooling process for cooling the material plate, the temperature of the material plate can be controlled to a desired temperature even when rolling in a plurality of passes is performed at high speed. Therefore, the temperature of the material plate does not become excessively high, the surface of the Mg alloy plate can be prevented from being burned, and sufficient processing strain can be imparted, so that the crystal structure can be made fine.

<< Test Example 1 >>
Using the rolling apparatus 100 described above, samples 1 to 6 of the Mg alloy plate were manufactured, and the surface state of the sample was evaluated.

  Specifically, it is composed of a Mg alloy equivalent to AZ91 (Al: 8.3% to 9.5%, Zn: 0.2% to 1.5% (all mass%)) by a twin roll casting method. Then, a cast plate having a plate thickness of 4.0 mm was prepared, wound into a coil shape, subjected to a solution treatment at 400 ° C. for 20 hours, and then set in the rolling apparatus 100. The cast plate 1 was heated to 250 ° C. in the heat box 2a, and the traveling speed was variously changed as shown in Table 1, and a plurality of passes were rolled under the following rolling conditions. Here, samples 1, 2, 5 and 6 were subjected to rolling in the first pass and second pass at a traveling speed of 30 m / min, and rolling of all subsequent passes was performed at the traveling speed shown in Table 1. . Samples 3 and 4 were rolled in all passes at the running speed shown in Table 1. Samples 1 and 2 have a warming pinch roll 4ah (4bh) on the feed side and a pinch roll 4bc (4ac) for cooling on the take-up side, and samples 3 to 6 have both the feed side and the take-up side. Pinch rolls 4ah and 4bh for heat insulation were used. Table 1 shows the temperature of each pinch roll 4. Moreover, the temperature of the raw material board 1 was measured in the said points AD (FIG. 1) during rolling. Table 1 shows the maximum temperature Tmax and the minimum temperature Tmin during all passes.

(Rolling conditions)
Rolling roll temperature: 230 ° C
Material plate temperature (reference temperature): 250 ° C
Total number of passes: 7 passes Reduction rate of each pass: 20% / pass to 25% / pass Total reduction rate: 80%
Plate thickness after rolling: 0.8mm
Length after rolling: 700m

[Surface observation]
The surfaces of the obtained samples 1 to 6 were visually observed, and the results are shown in Table 1. In this surface observation, when the surface is not burned, no single stretch or lateral flow is seen, and when the surface property is excellent (○), when the surface is oil burned (△), In addition, the case where one-side stretch or lateral flow was observed was taken as (x).

[result]
In Samples 1 to 4, the temperature of the material plate 1 could be 280 ° C. or lower over the entire pass, and the surface properties were excellent. In Samples 5 and 6, the temperature of the blank plate 1 exceeded 280 ° C., and the surface thereof was burned, and the sample 6 was also seen to be stretched (cross flow).

  It is considered that Samples 1 and 2 were able to control the temperature of the material plate 1 to 280 ° C. or lower over the entire pass by cooling the material plate 1 after the rolling process. In addition, since the sample 3 and 4 are low-speed driving | running | working speed of the raw material board 1 less than 40 m / min, since the atmospheric exposure time during driving | running | working is long, the raw material board 1 is easy to radiate heat. Therefore, the temperature of the material plate 1 can be controlled to a desired temperature by keeping the material plate 1 on both the feeding side and the winding side, so that the temperature of the material plate 1 can be controlled to a desired temperature even when a plurality of passes are rolled. It was because it was not expensive.

  Samples 1 and 2 are more excellent in moldability than samples 5 and 6. This is because Samples 1 and 2 were able to control the temperature of the blank plate 1 to 280 ° C. or lower over the entire pass, so that the processing strain due to rolling was sufficiently accumulated and the crystal structure was made fine by recrystallization. On the other hand, Samples 5 and 6 were because the temperature of the material plate 1 was 300 ° C. or higher, and the processing strain due to rolling was difficult to accumulate and the crystal structure could not be made fine.

  Note that the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist of the present invention. For example, the pinch rolls for cooling and heat insulation are not arranged individually, but the pinch rolls for both heat insulation and cooling having both the heating means and the cooling means are provided between the reels 10 a and 10 b and the rolling roll 3. You may arrange. Specifically, it is possible to use a pinch roll having a mechanism capable of circulating a heating fluid in the case of heat retention and a liquid refrigerant in the case of cooling. In this case, the raw material plate 1 can be cooled by switching the feeding direction to the forward direction and the returning direction, for example, by setting the feeding side for heat retention and the winding side for cooling.

  The manufacturing method of Mg alloy plate of this invention can be utilized for manufacture of Mg alloy plate. Further, the Mg alloy plate of the present invention can be used as a member of Mg alloy.

DESCRIPTION OF SYMBOLS 100 Rolling apparatus 1 Material board 2a, 2b Heat box 3 Rolling roll 4, 4ac, 4ah, 4bc, 4bh Pinch roll 10a, 10b Reel

Claims (6)

A feeding step of feeding a material plate made of a magnesium alloy and wound in a coil shape, a rolling step of rolling the fed material plate with a rolling roll, and a winding for winding the rolled material plate in a coil shape A rolling step, and at least the rolling step is performed on the heated material plate, and after the winding step, the wound material plate is again fed to the rolling roll to reciprocate the material plate. A method for producing a magnesium alloy plate that applies a plurality of passes of rolling to the material plate,
At least one of the plurality of passes is performed at a high speed of 40 m / min or more for the travel speed of the material plate,
Comprising a cooling step of cooling the material plate during the high-speed running,
By the cooling step, the temperature of the material plate is 280 ° C. or lower over the entire path ,
A method for producing a magnesium alloy plate , wherein the material plate is kept warm during at least one of the steps during traveling at a low speed of less than 40 m / min .   The method for producing a magnesium alloy sheet according to claim 1, wherein the cooling step is performed at least between the rolling step and the winding step. The manufacturing method of the magnesium alloy plate of Claim 1 or Claim 2 which contacts the said raw material board with the pinch roll whose surface temperature is 20 degreeC or more and 180 degrees C or less in the said cooling process. During the high speed running, between the feed-out step and the rolling step, and kept the blank, between the rolling step and the winding step, not warm the material plate according to claim 2 or claim 3 The manufacturing method of the magnesium alloy plate as described in any one of. Using a rolling device comprising a pinch roll for heat insulation and a pinch roll for cooling on each of the front and rear of the rolling roll,
Before the rolling step, the material plate is kept warm by the heat-insulating pinch roll, and after the rolling step, the material plate is cooled by the cooling pinch roll before and after the rolling roll, The method for manufacturing a magnesium alloy plate according to any one of claims 1 to 4 , wherein a cooling pinch roll is switched between the forward travel and the backward travel. The said magnesium alloy is a manufacturing method of the magnesium alloy plate of any one of Claims 1-5 containing 7 mass% or more and 12 mass% or less of aluminum.

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