A racquet includes a handle; and a frame connected to an end of the handle, the frame defining a rounded interior space, the frame including a negative Poisson's ratio (NPR) foam material, in which the NPR foam material, and in which the frame has a Poisson's ratio of between 0 and −1; and a network of strings stretched across the rounded interior space defined by the frame. A golf tee includes an elongated stem; and a head disposed at an end of the elongated stem and shaped to receive a golf ball; in which at least a portion of the golf tee is formed of a negative Poisson's ratio (NPR) foam material, in which the portion of the golf tee has a Poisson's ratio of between 0 and −1, and in which the NPR foam material includes an NPR metal foam, an NPR ceramic foam, or an NPR-PPR composite foam.

A racquet includes a handle; and a frame connected to an end of the handle, the frame defining a rounded interior space, the frame including a negative Poisson's ratio (NPR) foam material, in which the NPR foam material, and in which the frame has a Poisson's ratio of between 0 and −1; and a network of strings stretched across the rounded interior space defined by the frame. A golf tee includes an elongated stem; and a head disposed at an end of the elongated stem and shaped to receive a golf ball; in which at least a portion of the golf tee is formed of a negative Poisson's ratio (NPR) foam material, in which the portion of the golf tee has a Poisson's ratio of between 0 and −1, and in which the NPR foam material includes an NPR metal foam, an NPR ceramic foam, or an NPR-PPR composite foam.

The current invention aims at improving the playability, durability, and spin generation of different playing rackets, as tennis, squash, and badminton rackets. The method to do so is by applying mechanical forces which generate relative motion of the latitudinal strings over the longitudinal strings. This is done in order to create friction that generate depressions in the contact points of the latitudinal strings with the longitudinal strings. These depressions, made by the described method and machine, induce more friction, and generate spin, while increasing the playability and durability during the play.

The current invention aims at improving the playability, durability, and spin generation of different playing rackets, as tennis, squash, and badminton rackets. The method to do so is by applying mechanical forces which generate relative motion of the latitudinal strings over the longitudinal strings. This is done in order to create friction that generate depressions in the contact points of the latitudinal strings with the longitudinal strings. These depressions, made by the described method and machine, induce more friction, and generate spin, while increasing the playability and durability during the play.

A pulling string apparatus of a stringing machine comprising a string gripper, a sensor, a drive element, a transmission mechanism and a control circuit; the sensor is connected with the string gripper to detect the pull force of the string gripper; the control circuit compares the detected pull force value with a pre-set value, and control the rotation of the drive element; the transmission mechanism comprises a mounting base, a sliding block, a transmission rack and a drive gear; wherein the drive gear is connected to the drive element and is engaged with the transmission rack, the sliding block arranged on the transmission rack is connected with the sensor; when the sensor and the string gripper are driven forward or backward by the sliding block under the act of the transmission rack engaged with the drive gear, the racket string will be tensioned or loosened.

A pulling string apparatus of a stringing machine comprising a string gripper, a sensor, a drive element, a transmission mechanism and a control circuit; the sensor is connected with the string gripper to detect the pull force of the string gripper; the control circuit compares the detected pull force value with a pre-set value, and control the rotation of the drive element; the transmission mechanism comprises a mounting base, a sliding block, a transmission rack and a drive gear; wherein the drive gear is connected to the drive element and is engaged with the transmission rack, the sliding block arranged on the transmission rack is connected with the sensor; when the sensor and the string gripper are driven forward or backward by the sliding block under the act of the transmission rack engaged with the drive gear, the racket string will be tensioned or loosened.

An automatic string weaving system for weaving strings for a stringed sports racquet, comprising a weave assembly that the strings for the stringed sports racquet are weaved through; and an automated string feeder assembly to automatically weave the strings for the stringed sports racquet through the weave assembly.

An automatic string weaving system for weaving strings for a stringed sports racquet, comprising a weave assembly that the strings for the stringed sports racquet are weaved through; and an automated string feeder assembly to automatically weave the strings for the stringed sports racquet through the weave assembly.

An automatic string weaving system for weaving strings for a stringed sports racquet, comprising a weave assembly that the strings for the stringed sports racquet are weaved through; and an automated string feeder assembly to automatically weave the strings for the stringed sports racquet through the weave assembly.

An automatic string weaving system for weaving strings for a stringed sports racquet, comprising a weave assembly that the strings for the stringed sports racquet are weaved through; and an automated string feeder assembly to automatically weave the strings for the stringed sports racquet through the weave assembly.