1. Field of the Invention
This invention relates to open-end spinning machines for producing textile yarns, and particularly to a method and apparatus for starting a spinning operation in an open-end spinning machine.
2. Description of the Related Art
In British Pat. No. 2,019,451 there are described two starting procedures for an open-end spinning machine.
The first, shown in FIG. 1, uses reversal of the yarn delivery rollers at a controlled rate to re-introduce the end of the yarn into the spinning chamber at a controlled rate to effect piecing. Upon completion of piecing, the rollers rotate in the yarn withdrawal direction and normal spinning resumes.
In the second entirely different described procedure, shown in FIG. 3 of British Pat. No. 2,019,451, a retractable yarn guide is used for forming a reserve loop of yarn upstream of the delivery rollers, and the piecing operation later involves the step of shortening the reserve length of yarn so as to enable the end of yarn to move to the fibre collecting surface of a spinning rotor and twist in the fibres fed thereto. The step of forming the reserve length of yarn in this second procedure conveniently takes place during the the preceding stopping procedure by engagement of the yarn with the reserve forming member which is caused to move in a longitudinal direction at a slow rate of traverse.
It has been found to be disadvantageous in some situations to form the reserve length of yarn during the stopping procedure. It is, of course, a requirement of a satisfactory stopping procedure that, upon the termination of a spinning operation, all of the ends of yarn are at a position in which they can be returned automatically to the spinning rotor, and that the various fibre and yarn handling components are stopped in accordance with a predetermined programme. However it has been found difficult to accomplish this stopping programme in the event of a failure in the supply of electrical power to the machine, even when an auxiliary source of electrical power, such as, for example, batteries, can be utilised upon such power failure. It is therefore advantageous if the stopping prodedure can be shortened so that the auxiliary source is capable of supplying electrical power for a sufficient length of time for a satisfactory stopping procedure to be carried out.
One way of achieving a shortened stopping procedure is to omit from it the step of forming the reserve length of yarn and to include this step in the starting procedure as disclosed in the first of the two procedures disclosed in British Pat. No. 2,019,451. Moreover, this has the disadvantage that the reversal of the yarn package, finding of the yarn end, and delivery of it to the spinning chamber all occur in a continuous sequence and, as a result prolong the piecing procedure.