Cookware for Making Youtiao Field of the Invention The invention relates to a kitchen cookware, especially to a cookware for making youtiao. 5 Description of prior art Currently the cookware for making youtiao has a round shape, youtiao floated on the surface of oil would move to the edge of the cookware under the flow effect, youtiao would bend in a shape 10 similar to the shape of the edge, the shape of youtiao turns into arcuate shape resulted in reducing the qualification rate of youtiao. In order to maintain the straight shape of youtiao, the youtiao should be manually placed back to the middle portion of the wok to be continued on frying. There are a plurality of youtiaoes fried 15 together in the cookware at the same time for increasing productivity, becaue of the round shape of cookware and the strip profiled shape of youtiao, the area where can hold a totally straight youtiao is the middle portion of the cookware, the portion close to the edge can not hold a totally straight youtiao, unless youtiao has a 20 bending shape, but a youtiao with bending shape is not a conforming product, so the cookwar with a round shape has a low productivity, it is need to continually hold the positon of youtiao in the cookware during the frying process, the action is manual, so the labor cost in increased. 25 How to avoid youtiao from bending, maintaining the straight shape of youtiao with no manual intervention so as to increase the qualification and reduce the labor cost, it is a problem waiting to be solved. 30 1/7 Summary of the present invention The object of the invention is to provide a cookware for making youtiao. 5 Therefore, the invention provides a cookware for making youtiao, the cookware comprises a first plane located at the bottom of the cookware; above the first plane locate a second plane, a third plane, a first arcuate surface, a second arcuate surface and a third arcuate surface; the second plane transitions to the first plane throuth the 10 second arcuate surface, the third plane transitions to the first plane through the third arcuate surface, the second plane transitions to the third plane through the first arcuate surface; the area surrounded by the first plane, the second arcuate surface, the first arcuate surface and the third arcuate surface being defined as a 15 heat collecting area, the area with a square opening facing up surrounded by the second plane, the first arcuate surface, the third plane, the front vertical plane and the rear vertical plane is defined as a receiving area, both the front and rear vertical planes are vertical to the second and third plane, the receiving area is with a 20 shape with wide top and narrow bottom. Preferably, the second plane and the third plane are symmetrically arranged about the central plane of the first arcuate surface, and the second plane and the third plane are vertical to each other. 25 Preferably, the second arcuate surface and the third arcuate surface are symmetrically arranged about the central plane of the first arcuate surface. 30 Advantageous Effects 1. Because the heat collecting area is located below the first arcuate surface, the temperature of the first arcuate is obviously higher than the temperature of the second and third plane located on both 2/7 sides of the first arcuate surface, therefore oil near the first arcuate surface moves up under the effect of the temperature difference, while oil near the second or third plane moves down to the first arcuate surface, youtiao floated on the surface of oil moves to the 5 edge of the cookware, and stops at the edge, because the edge of the cookware that is the second or third plane is with a plane shape, youtiao has a straight shape, so the qualification rate is increased. 2. The straight youtiao rolls slowly at the edge of the cookware 10 under the flow effect, rolling is good for youtiao to heat evenly so as to make youtiao with good appearance, and with the same color. 3. The receiving area with a square opening can fry a plurality of youtiaoes together at the same time, and each youtiao is straight, 15 so the productivity is increased. Brief description of the drawing In the following, the invention will be described in greater detail by means of some embodiments with reference to the accompanying 20 drawings, in which Fig.1 is a 3d-drawing of cookware for making youtiao of the invention; Fig.2 is a sectional view of Fig.1; Fig.3 is a 3d-drawings of making youtiao in round cookware; 25 Fig.4 is a top view of Fig.3; Fig.5 is a 3d-drawing of pouring oil from round cookware to the cookware shown in Fig.1; Fig.6 is a 3d-drawing of making youtiao in cookware shown in Fig.5; Fig.7 is a top view of Fig.6; 30 Fig.8 is a sectional view of round cookware shown in Fig.3; Fig.9 is a sectional view of the cookware shown in Fig.1. 1. the first plane; 2. the second plane; 3. the third plane; 4. the first arcuate surface; 5. the second arcuate surface; 3/7 6. the third arcuate surface; 7. the heat collecting area; 8. the youtiao; 9.the front vertical plane; 10. the rear vertical plane. Detailed description of the preferred embodiment Fig.1 is a 3d-drawing relative to an embodiment of a cookware 5 according to the present invention. The cookware comprises a receiving area with a square opening facing up and with a square shape, the receiving area consists of a front vertical plane 10, a rear vertical plane 10, a second plane 2, a third plane 3 and a first arcuate surface 4. The front vertical plane 10 is parallel with the rear 10 vertical plane 10, the second plane 2 is vertical to the front and rear vertical plane 9,10, the third plane 3 is vertical to the front and rear vertical plane 9,10, the second plane 2 and the third plane 3 are tilted to each other so as to form a receiving area with wide top and narrow bottom. 15 Referring to Fig.2, a first plane 1 which is below the receiving area is arranged at the bottom of the cookware, the second plane 2 transitions to the first plane 1 through the second arcuate surface 5, the third plane 6 transitions to the first plane 1 through the third 20 arcuate surface 6, the second plane 2 transitions to the third plane 3 through the first arcuate surface 4. The second plane 2 and the third plane 3 are symmetrically arranged about the central plane of the first arcuate surface 4, the second plane 2 and the third plane 3 are vertical to each other, the second arcuate surface 5 and the third 25 arcuate surface 6 are symmetrically arranged about the central plane of the first arcuate surface 4. There is a heat collecting area 7 arranged between the receiving area and the first plane 1, the area surround by the first plane 1, the second arcuate surface 5, the first arcuate surface 4 and the third arcuate surface 4 is defined as a heat 30 collecting area 7. Referring to Fig.3 and Fig.4, it is a view of making youtiao by traditional cookware with a round shape, oil flows in the wok due to 4/7 the effect of the temperature difference when oil is heated, referring to Fig.8. The youtiao in the round wok moves to the edge of the wok under the flow effect, finally the youtiao is at edge of the wok, the youtiao bends in a shape similar to the shape of the edge 5 due to staying at the edge for a long time, the shape of youtiao turns into arcuate shape, a youtiao with bending shape is not a conforming product, in order to maintain the straight shape of youtiao, youtiao should be manually placed back to the middle portion of the wok to be continued on frying so as to make a 10 conforming product. There are a plurality of youtiaoes fried together in the cookware at the same time for increasing productivity, becaue of the round shape of cookware and the strip profiled shape of youtiao, the area 15 where can hold a totally straight youtiao is the middle portion of the cookware, the portion close to the edge can not hold a totally straight youtiao, unless youtiao has a bending shape, but a youtiao with bending shape is not a conforming product, so the cookware with a round shape can only make three conforming youtiaoes from 20 five youtiaoes with no manual intervention. Fig.5 is a 3d-drawing of pouring oil from round cookware to the cookware shown in Fig.1, in order to make comparison between the square cookware and the traditional round cookware. Referring to 25 Fig.9, the receiving area has a structure with wide top and narrow bottom, the heat collecting area 7 is located below the first arcuate surface 4, so the temperature of the first arcuate surface 4 is obviously higher than the temperature of the second plane 2 or the third plane 3 located on both side of the first arcuate surface 4, 30 therefore oil near the first arcuate surface moves up under the effect of the temperature difference, while oil near the second or third plane 2,3 moves down to the first arcuate surface 4, youtiao floated on the surface of oil moves to the edge of the cookware, and stops at the edge, because the edge of the cookware that is the 5/7 second or third plane 2,3 is with a plane shape, youtiao has a straight shape, the youtiao is a conforming product. There are a plurality of youtiaoes fried together in the cookware at 5 the same time for increasing productivity, five youtiaoes can be hold in the receiving area according to the oil quantity in the receiving area, because the receiving area has a square opening while the youtiao has a strip profiled shape, five youtiaoes can be placed one by one in the receiving area, the straight youtiao rolls around its axis 10 in the receiving area under the flow effect, especially youtiao rolls slowly at the edge of the cookware, rolling is good for youtiao to heat evenly so as to make youtiao with good appearance, and with the same color. Therefore, the square cookware can fry five conforming youtiaoes with no manual intervention, referrign to 15 Fig.6 and Fig.7. When the first plane 1 of the cookware is places on the heat source, the heat passes through the first plane 1 to the heat collecting area 7. Because the heat collecting area 7 is a solid, it collects more heat, 20 then the heat passes through the first arcuate surface 4, the second plane 2 and the third plane 3 to the oil in the receiving area so as to increase the temperature of oil. The first plane 1 of the cookware can be placed on the fire to heat 25 directly, when the material of the cookware is metal, such as iron, aluminum, copper or alloy. When the material of cookware is iron, the first plane 1 of the cookware can be placed on the electromagnetic oven. 30 The temperature of oil in the receiving area changes slowly due to the effect of the heat collecting area 7, especially when a plurality of doughs are just placed into the cookware, the temperature of oil reduces down, but the heat from heat collecting area 7 supplies the 6/7 lost heat quicklyso as to slow down the temperature drop, thus the temperature of oil is still in the frying range. The oil in the receiving area is mainly heated by the first arcuate 5 surface 4 above the heat collecting area 7 and assistantly heated by the second and third plane 2,3, such arrangement increases an oil flow in the middle portion of the receiving area, that is above the first arcuate surface 4 moving up along the its axis, and increases an oil flow near the second or third plane 2,3 moving down, so the oil 10 on the surface moves from the middle portion of the cookware along the axial direction of the first arcuate surface 4 to the edge of the cookware. Thus the youtiao moves directionally to the edge of cookware after rising to the surface of oil, rather than to rotate in clockwise or anticlockwise direction on the oil surface. After the 15 youtiao moves to the edge of the cookware, the straight youtiao rolls around its axis in the receiving area under the flow effect, rolling is good for youtiao to heat evenly so as to make youtiao with good appearance, and with the same color. When there are a plurality of youtiaoes in the cookware, youtiaoes arrange 20 themselves into a queue as shown in Fig.6 and Fig.7. The oil on the surface moves radially to the edge of the round cookware because the heating plane at the bottom of the wok is circular. So the youtiao rotates in clockwise or anticlockwise 25 direction on the oil surface so as to make the length direction of youtiao align with the radial direction of the wok as moving to the edge of cookware. When there are a plurality of youtiaoes in the wok, them collide to one another and arrange higgledy-piggledy in the wok resulted in wasting space, it is need to make them in order 30 with manual intervention so as to place more youtiaoes in the wok. The arcuate surface is arranged to connect planes to make the temperature distribution and transmission more even, and such arrangement is convenient for manufacturing. 7/7