Dosing unit for assembly line for magnet group Field of the Invention The invention relates to an assembly line for the magnet group, especially to a dosing unit thereof. Description of prior art 5 A magnetic turntable is disclosed in the patent AU2015100319, there are provided a plurality of arrays of magnet groups, each magnet group consists of 16 pieces of permanent magnet arranged alternately. Currently, each magnet group is assembled by hand, due to the small size of each magnet and the thin thinkness of the 10 magnet, it is difficult to assemble magnet groups, the efficiency is low, and mistake is offen taken resuting that a plurality of magnets are gravitated together by magnetic force. It is unhealthy to repeat doing one thing by keeping a posture for a long time, so the production capacity is depended on working time. 15 Summary of the present invention The object of the invention is to provide a dosing unit for the assembly line for the magnet group so as to solve the above problem. The unit has the function of correctly assembling a plurality of magnets in an alternating manner, and the function is 20 automatic and efficient. In the following, the technical solution will be discribed. A dosing unit for the assembly line for the magnet group comprises N and S pole conveyor tracks, an output conveyor track and a kick-out unit; the dosing uint further comprises a N pole rotary shaft 25 and a S pole rotary shaft, the gripper jaws of the turntable of the N pole rotary shaft are arranged alternately to the gripper jaws of the turntable of the S pole rotary shaft, N and S pole rotary shaft have a synchrodrive via transmission mechanism with opposite dirction of rotating. The kick-out unit stores energy via the cam, and triggers 30 the kicking rod quickly, evey sigle permanet magnet flies into the 1/5 gripper jaw due to the kicking rod impacting the magnet, because of the magnetic stationary block arranged to the gripper jaw the magnet is conveyed stably to the output conveyor. There is also provided a power input disc to the S pole rotary shaft. 5 Preferably, the synchrodrive of N and S pole rotary shaft is achieved by gears meshing, and the shaft, from top to bottom, provides the gear, the cam and the turntable, the turntable equally provides six gripper jaws. Equivalently, when the power input disc of the S pole rotary shaft is 10 moved to the N pole rotary shaft, it makes no difference with respect to the assemblling effect of the automatically dosing unit. Due to the opposite directions of the rotation of the N and S pole rotary shaft and the alternating arrangment of the gripper jaws of the turntable of the N and S pole rotary shaft, such that the dosing 15 unit can correctly and efficiently assemble a plurality of magnets by an alternating manner so as to reduce labor intensity and increase production capacity. Brief description of the drawing In the following, the invention will be described in greater detail by 20 means of some embodiments with reference to the accompanying drawings, in which Fig.1 is a 3d-drawing of the dosing unit for the assembly line for the magnet group; Fig.2 is a 3d-drawing of the S and N pole rotary shaft meshing; 25 Fig.3 is a front view of Fig.2; Fig.4 is a top view of Fig.3; Fig.5 is an exploded 3d-drawing of the S pole rotary shaft; Fig.6 is a 3d-drawing of the turntable; Fig.7 is an exploded 3d-drawing of the gripper jaw; 30 1. the N pole conveyor track; 2. the S pole conveyor track; 3. the output conveyor track; 5. the N pole rotary shaft; 6. the S pole rotary shaft; 7. the kick-out unit; 9. the turntable; 91. the gripper jaw; 92. the first opening; 2/5 93. the stationary block; 10. the cam; 11. the gear; 12. the power input disc; 13. the sleeve; 14. the shaft; 15. the key. Detailed description of the preferred embodiment 5 Referring to Fig.1, there is provided a dosing unit for the assembly line for the magnet group, the dosing unit comprises a N pole conveyor track 1, a S pole conveyor track 2 and an output conveyor track 3. The end portions of N and S pole conveyor track 1,2 and the output conveyor track 3 are parallel to one another, the output 10 conveyor track 3 is arranged between the N pole conveyor track 1 and the S pole conveyor track 2, the N pole rotary shaft 5 is arranged between the N pole conveyor track 1 and the output conveyor track 3, the S pole rotary shaft 6 is arranged between the S pole conveyor track 2 and the output conveyor track 3, the N and S 15 pole rotary shaft 5,6 are arranged to be paralle and to close to the ends of the N and S conveyor track 1,2. The kick-out unit 7 is arranged to each end of N and S pole conveyor track 1,2, the head portions of the kicking rods of the kick-out unit 7 are arranged to be opposite. The permanent magnets with the N pole facing up are 20 conveyed incessantly to the skidway of the kick-out unit 7 along the N pole conveyor track 1, the permanent magnets with the S pole facing up are conveyed incessantly to the skidway of the kick-out unit 7 along the S pole conveyor track 2. Referring to Fig.2 to Fig.4, the gripper jaws 91 of the turntable 9 of 25 the N pole rotary shaft 5 are arranged alternately to the gripper jaws 91 of the turntable 9 of the S pole rotary shaft 6. The power is input to the power input disc 12 of the S pole rotary shaft 6 by the belt, N and S pole rotary shaft 5,6 have a synchrodrive via transmission mechanism with opposite dirction of rotating, it is 30 achieved by gear meshing of two gears with same teeth number and module. The kick-out unit 7 stores energy via the cam 10, and triggers the kicking rod quickly, evey sigle permanet magnet flies into the 3/5 gripper jaw 91 due to the kicking rod impacting the magnet, because of the magnetic stationary block 93 arranged to the gripper jaw the magnet is conveyed stably to the output conveyor. The permanent magnets with N pole facing up are conveyed to the 5 output conveyor track 3 by N pole rotary shaft 5, meanwhile, the permanent magnets with S pole facing up are conveyed to the output conveyor track 3 by S pole rotary shaft 6, because the gripper jaws 91 of the turntable 9 of the N pole rotary shaft 5 are arranged alternately to the gripper jaws 91 of the turntable 9 of the 10 S pole rotary shaft 6, permanet magnes with the N pole facing up and permanet magenets with the S pole facing up are conveyed alternatively to the output conveyor track 3, the purpose of the invention is achieved. Referring to Fig.6, there are provided equally six gripper jaws 91 to 15 the turntable 9, each gripper jaw 91 provides a first opening 92 for gripping the permanent magnet, a magnetic stationary block 93 are located to the bottom of the first opening 92. Referring to Fig.7, two magnetic stationary blocks 93 are arranged symmetrically to the both sides of the gripper jaw 91, they are fixed to the bottom of the 20 first opening 92 by screws, the width of the stationary block 93 is greater than the width of the first opening 92, chamfers for guiding the permanent magnet easily into the opening are arranged to the entrance of the first opening 92, the permanet magnet matches the gap of the first opening 92, that is, the width of the first opening 92 25 is slightly greater than the width of the single magnet, due to this arrangement the conveying of magnets to the output conveyor track 3 is free from jam. The reason for the jam is that a stationary joining element is formed by the guiding direction of the output conveyor track 3 and the rotating direction of the turntable 9, that is, the 30 width of the first opening 92 is not greater than the width of the magnet, if the width of the first opening 92 is greter than the width of the magnet, the stationary joining element is changed to movable joining element. Referring to Fig.5, the S pole rotary shaft 6, from top to bottom, 4/5 provides a gear 11, a cam 10 and a turntable 9, the power input disc 12 is arranged under the gear 11, the heights of the gear 11, the cam 10, the turntable 9 and the power input disc 12 are adjusted by the sleeves 13. The synchrodrive of the gear 11, the cam 10, the 5 turntable 9 and the power input disc 12 is achieved by the cooperation between the shaft 14 and the key 15. Except the stationary block 93 is magnetic, like iron, the other parts disclosed in the embodiment are nonmagnetic like plastics, aluminium and copper. 10 The second embodiment when the power input disc 12 of the S pole rotary shaft 6 is moved to the N pole rotary shaft 5, it makes no difference with respect to the assemblling effect of the automatically dosing unit, that is, permanet magnes with the N pole facing up and permanet 15 magenets with the S pole facing up are conveyed alternatively to the output conveyor track 3, the purpose of the invention is achieved. 5/5