Aspects of the design of a circular warp knitting machine

The warp knitting machine market has long been dominated by large-scale flat models, which have been steadily developed. Tubular fabrics are generally made in a special version of flat warp knitting machines containing two needle bars, one for each side of the tube, joined on the sides by yarns knitting alternatively on each bar. Warp knitting technology has failed to enter the circular knitting industry, dominated by weft knitting, due to its complexity in achieving warp knit structures in circular form. This thesis presents the design, synthesis, manufacture and test of an innovative method of producing tubular warp knitting fabrics, using a circular format rather than flat needle bars. This novel concept opens up many industrial applications from medical textiles to fruit packaging. [Continues.

Optimising cam motion using piecewise polynomials

The paper presents a method of synthesising cam profiles based on the use of piecewise polynomials together with an optimisation technique. Special cases and limitations are discussed and illustrated, making the procedure complete and systematic for any design requirements. Using piecewise polynomials, the complete cam profile can be designed as a combined linear system. The optimisation technique described goes even further, manipulating the variables in the linear system to select the ideal combination. In addition, a means to prove the validity of the results is explained

Modelling the pattern creation process for the optimum design of a circular warp-knitting machine using a conical needle-bed

A circular warp-knitting machine was designed using a novel approach that uses a conical needle-bed. This machine was built and successfully tested. The interaction between the patterning and knitting mechanisms of a warp-knitting machine is critical for the performance of the machine. In a circular warp-knitting machine, geometric parameters such as the diameter of the patterning rings and the distance between the patterning rings and the needles can significantly affect the patterning capability of the machine. This paper describes an approach to modelling the yarn and needle paths in a novel circular warp knitting machine with a conical needle-bed and patterning rings, using equations that govern the relationship between the different geometric parameters in order to calculate the amplitude of the shogging movements and optimise machine performance. A set of mathematical equations governing the geometric relationship that determines the limits of the motion of the patterning rings is presented. The algorithms have been created and successfully tested using a case study. A mathematical model and appropriate algorithms are developed that prove useful design tools for the designer of the circular warp knitting machines using conical needle-bed

Design and development of a novel circular warp knitting machine

This paper reports the design, manufacture and test of an innovative method of producing warp knitting fabrics, using a circular disposition of the needles rather than linear needle bars. By using the novel truncated-cone needle-bed concept instead of a cylindrical one, the needles slide simultaneously in radial and vertical directions to combine the reciprocating and swinging motions into one. Initially a mechanical prototype machine was designed, built and successfully tested to prove the knitting mechanism and its interaction with the patterning rings. The second prototype has a mechatronic patterning mechanism, hence increasing the patterning capabilities significantly, and enabling changing fabric pattern change during knitting without requiring long machine stoppages and cam changes

Cognitive Information Processing

Contains reports on four research projects.National Science Foundation (Grant G-16526)National Institutes of Health (Grant MH-04737-03)National Aeronautics and Space Administration (Grant NsG-496

Patterning servo-mechanism for a circular warp knitting machine

Warp knitting is always performed on flat (linear) knitting machines. A circular warp-knitting machine is recently made possible by using a novel concept of a conical needle bed and patterning cams with enclosed cam followers to drive the patterning rings. This also requires a mechanical linkage to transmit the motion from the patterning cam to the patterning rings, which is prone to vibration at undesirable levels. A new generation design replaces the mechanical cam and linkage with high-speed AC brushless servomotors enabling limitless precision patterning possibilities. A method of selecting servomotors based on minimising the power required to perform the fastest motion required for a given application is reported. This method ensures cost minimising by selecting the smallest servomotor suitable for a given application. A circular warp-knitting machine using servomotor to drives selected using the method reported is designed, built and successfully tested

Communications Biophysics

Contains reports on six research projects.National Science Foundation (Grant G-16526)National Institutes of Health (Grant MH-04737-02