Inner Liner for Cookware for Making Youtiao Field of the Invention The invention relates to a cookware for making youtiao, especially to an inner liner. 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 an inner liner for cookware for making youtiao. 5 Therefore, the invention provides an inner liner for cookware for making youtiao, the inner liner comprises a receiving area, the inner liner further comprises a first plane, a second plane and a first arcuate surface. The second plane transitions to the first plane through the first arcuate surface, the area with a square opening 10 facing up surrounded by the first plane, the first arcuate surface, the second plane, the front vertical plane and the rear vertical plane is defined as a receiving area, both the front and rear vertical plane are vertical to the first and second plane, the receiving area is with a shape with wide top and narrow bottom. 15 Specifically, a vertical rim extends outwardly perpendicularly from the edge of the square opening. Preferably, a portion near the opening of the front or rear vertical 20 plane has a lip projecting outwardly from the portion. Preferably, the first plane and the second plane are symmetrically arranged about the central plane of the first arcuate surface, the first plane and the second plane are vertical to each other. 25 Preferably, the material of inner liner is food grade stainless steel. Advantageous Effects 1. Because the temperature of the first arcuate is obviously higher 30 than the temperature of the first and second plane located on both 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 first or second plane moves down to the first 2/7 arcuate surface, 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 first or second plane is with a plane shape, youtiao has a straight shape, so the qualification rate is increased. 5 2. The straight youtiao rolls slowly at the edge of the cookware 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. 10 3. The receiving area with a square opening can fry a plurality of youtiaoes together at the same time, and each youtiao is straight, so the productivity is increased. Brief description of the drawing 15 In the following, the invention will be described in greater detail by means of some embodiments with reference to the accompanying drawings, in which Fig.1 is a 3d-drawing of inner for cookware for making youtiao of the invention; 20 Fig.2 is a sectional view of Fig.1; Fig.3 is a 3d-drawings of making youtiao in round cookware; 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; 25 Fig.6 is a 3d-drawing of making youtiao in inner liner shown in Fig.5; Fig.7 is a top view of Fig.6; Fig.8 is a sectional view of round cookware shown in Fig.3; Fig.9 is a sectional view of inner liner shown in Fig.1. 1. the first plane; 2. the second plane; 3. the first arcuate surface; 30 4. the front vertical plane; 5. the rear vertical plane; 6. the vertical rim; 7. the lip; 8. the youtiao. Detailed description of the preferred embodiment 3/7 Fig.1 is a 3d-drawing relative to an embodiment of a inner liner for cookware according to the present invention. The receiving area formed by the main body has a square opening facing up, the receiving area is surrounded by a front vertical plane 5 4, a rear vertical plane 5, a second plane 2, a frist plane 1 and a first arcuate surface 3. The front vertical plane 4 is parallel with the rear vertical plane 5, the first plane 1 is vertical to the front and rear vertical plane 4,5, the second plane 2 is vertical to the front and rear vertical plane 4,5, the first plane 1 and the second plane 2 are tilted 10 to each other so as to form a receiving area with wide top and narrow bottom. A vertical rim 6 extends outwardly perpendicularly from the edge of the square opening, a portion near the opening of each the front or rear vertical plane 4,5 has a lip 7 projecting outwardly from the portion. 15 Referring to Fig.2, the first plane 1 transitionis to the second plane 2 through the first arcuate surface 3, the second plane 1 and the second plane 3 are symmetrically arranged about the central plane of the first arcuate surface 3, the first plane 1 and the second plane 20 2 are vertical to each other. 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 the effect of the temperature difference when oil is heated, 25 referrign 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 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 30 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 conforming product. 4/7 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 where can hold a totally straight youtiao is the middle portion of the 5 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 five youtiaoes with no manual intervention. 10 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. Putting the inner liner in the wok support (see Fig.10), the first arcuate surface 15 3 is arranged to main heating surface, the first and second plane 1,2 are arranged to be the auxiliary heating surface. Referring to Fig.9, the receiving area has a structure with wide top and narrow bottom, because the first arcuate surface 3 is arranged to the main heating surface, the temperature of the first arcuate surface 3 is obviously 20 higher than the temperature of the first plane 1 or the second plane 2 located on both side of the first arcuate surface 3, therefore oil near the first arcuate surface moves up under the effect of the temperature difference, while oil near the first or second plane 1,2 moves down to the first arcuate surface 3, youtiao floated on the 25 surface of oil moves to the 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, the youtiao is a conforming product. 30 There are a plurality of youtiaoes fried together in the square inner liner at 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 5/7 placed one by one in the receiving area, the straight youtiao rolls around its axis 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, 5 and with the same color. Therefore, the square cookware can fry five conforming youtiaoes with no manual intervention, referrign to Fig.6 and Fig.7. The oil in the receiving area is mainly heated by the first arcuate 10 surface 3 and assistantly heated by the first and second plane 1,2, such arrangement increases an oil flow in the middle portion of the receiving area, that is above the first arcuate surface 3 moving up along the its axis, and increases an oil flow near the first or second plane 1,2 moving down, so the oil on the surface moves from the 15 middle portion of the inner liner along the axial direction of the first arcuate surface 3 to the edge of the inner liner. Thus the youtiao moves directionally to the edge of inner liner after rising to the surface of oil, rather than to rotate in clockwise or anticlockwise direction on the oil surface. After the youtiao moves to the edge of 20 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 themselves into a queue as shown in 25 Fig.6 and Fig.7. Oil in the receiving area can be poured conveniently to the container through the lip projecting outwardly from the portion near the opening of the front or rear vertical plane 4,5, after the frying process is finished. 30 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 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 6/7 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 with manual intervention so as to place more youtiaoes in the wok. 5 The arcuate surface is arranged to connect planes to make the temperature distribution and transmission more even, and such arrangement is convenient for manufacturing. 10 Because the material of inner liner is food grade stainless steel, youtiao fried from the inner liner is safe to eat. 7/7