The invention discloses a straight twisting
machine, and belongs to the field of
textile machinery. The problems that external
yarn tension control is not accurate, and an optimum ballooning shape cannot be reached exist in the existing straight twisting
machine. The straight twisting
machine is characterized in that an external
yarn sensor is arranged in an external
yarn path between a twisting tray and an external yarn tensioner and used for detecting an external yarn linear speed and external
yarn tension; a strand yarn sensor is arranged in a strand yarn path between an overfeeding device and an even twisting device and used for detecting a strand yarn linear speed and strand
yarn tension; a motor sensor is arranged on a spindle
drive motor and used for detecting a
motor speed and current; the external yarn tensioner and an overfeeding wheel of the overfeeding device are respectively driven by separate motors; a
control system connected with the motors is connected with the external yarn sensor, the strand yarn sensor and the motor sensor; and by taking the external yarn speed, the external
yarn tension, the spindle
drive motor speed, the current, the strand yarn linear speed and the strand yarn tension as parameters, the
control system controls the external yarn tensioner to actively feed yarns at a
constant speed or a variable speed, adjusts a strand yarn pulling speed, and ensures that a tension value of an external yarn can allow a wrapping angle to be minimum.