GB2034920A - Control systems for circular knitting machines - Google Patents

Abstract

An electronic control system for a circular knitting machine for replacing the conventional program chain comprises a matrix M programmed with removable programming members in the form of pins. Comparator means 110 and decoder means 101 associated with the matrix provide output signals determined by the program for controlling actuators on the machine. A plurality of unsynchronized machines may be controlled simultaneously by a microprocessor (not shown) accessing the appropriate control instruction for each machine, from the matrix program in multiplex fashion. The programmed information may be a series of instructions comprising type of operation, speed and number of repetitions. <IMAGE>

Description

SPECIFICATION Control systems for circular knitting machines The present invention relates to circular knitting machines.

In conventional circular knitting machines for knitting stockings and the like, the complete program required for making an entire article is contained on a chain which is moved synchronously with the rotation of the needle cylinder, and which also serves to control the stepwise advancement of a cam drum. The control data is represented by links projecting from the chain and which raise or otherwise operate members provided for the various functions to be carried out. The length and format of the program can be varied by adding or removing links to or from the chain, and by suitably returning the chain into tension by suitable tensioning devices. Besides considerable complications and bulk, this system makes any program modification very laborious.

According to the present invention, there is provided an electronic control system for a circular knitting machine including a rotatable needle cylinder, a control cam drum movable stepwise, and actuators, said control system comprising a matrix, removable programming members for programming said matrix, sensor means for determining revolutions of the machine and the end of a knitting cycle, and means associated with the matrix for providing output signals determined by the program for controlling the actuators on the machine.

The matrix can comprise seats for the programming members the seats being arranged in rows for determining successive stages in the program, and in columns for providing speed control signals (at least two values), stepwise movement control signals for the drum, control signals for various operations (such as contraction etc.) and for setting the required numbers of revolutions in each stage.

The system preferably enables more than one machine to be controlled.

For this purpose, the system includes a microprocessor unit which simultaneously and independently controls more than one machine from the same program matrix, and comprising sensors and actuators on each machine, and output data lines to the actuators of each machine in order to supply the data pertinent to each machine according to the stage in which it is operating. The microprocessor can comprise program memories associated with the individual machines controlled.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a circuit diagram of an electronic control system in accordance with the present invention; Figure 2 shows schematically a programming matrix of the system; and Figure 3 is a block circuit diagram of a system for controlling simultaneously a plurality of knitting machines.

The programming system shown in the drawings comprises a matrix M for a series of removable programming members in the form of pins, the number of pins inserted in the matrix and the position of the pins determining the required program. The matrix with the pins therein constitutes a non-erasable programming member. The matrix is such as to allow the set program to be easily checked, and the program can be easily varied by moving, adding, or extracting pins.

A matrix M for providing an entire range of possible programs can consist of 1 6 rows and 32 columns, as shown in Fig. 2. In practice, the program structure can comprise a number of rows of seats, in this case 32, with the seats arranged for example into a series of columns D headed as follows: average speed MED; maximum speed MAX; drive jack control CR; contraction control RG; auxiliary AU.

The region denoted by G comprises columns allotted to specific numbers of revolutions (in this example 1, 2, 4, 8, 16, 32, 64 etc.) which can be added together to provide a required number of revolutions.

As can be seen from Fig. 1, the matrix M is combined with an output interface 101 in such a manner that it is connected by, for example, four channels 103 to the actuators disposed on the machine. The reference numeral 105 indicates a sensor for counting the revolutions of the needle cylinder, which by way of an interface 107 acts on a revolution counter 109. The reference numeral 110 indicates a comparator which has one input 1 101 associated with the matrix M and another input 1102 associated with the comparator 109. The reference numeral 112 indicates a sensor for sensing the end of the cycle, combined for example with the cam drum. This sensor is co-ordinated by way of an interface 11 4 and a gate with a level counter 1 20 and with the revolution counter 109.The reference numeral 122 indicates a level decoder, which is co-ordinated with the matrix.

Referring to the matrix arrangement of Fig.

2, in which the presence of pins in the seats is indicated by dark dots, it will be noted that, for example, row 3 (which represents the 3rd stage in the program) is set to cause the cylinder to make 1 + 2 + 8 = 11 revolutions at maximum speed MAX. In the subsequent 4the stage, two revolutions are made at average speed MED by means of two jack movements (i.e. by two stepwise advancements of the cam drum, one for each revolution). In the 5th stage, 8 + 1 6 = 24 revolutions are made at maximum speed MAX, and so forth.

In this embodiment, the entire program is effected in not more than 30 steps. There are only 12 control signals for the drive jack.

Each step of the program has a duration equal to the number of programmed revolutions, as determined in region G.

The described system, using the data contained for example in the matrix heretofore described, can control one or more machines simultaneously, and in this particular ease up to five machines.

Assuming that only one machine is to be controlled, then the system operates as follows: The revolution and last run signals (clock pulses2 are taken from the two sensors 105 and 112 (which can be optical) disposed on the machine.

When the pins have been inserted in accordance with the required program, this program can be immediately started.

When the machine is started, the revolution counter 109 and level counter 1 20 are automatically reset to zero, and the level decoder 1 22 is effective on the first row of the matrix M. The data at the input 1 10, of the comparator 110 is dependent on the arrangement of the pins in the first row.

For each revolution of a member associated with the needle cylinder, such as a drive gear wheel, the revolution counter 105 advances through one step, i.e. one bit. When the data at the input 1102 of the comparator 110 corresponds to that provided at the input 1 10, by the first row of matrix M, the comparator 110 gives a pulse which sets the revolution counter 105 to zero and causes the level counter 1 20 to advance through one step. The level decoder 122 is then effective on the second row of the matrix M, and the data at the input 1 10, of the comparator 1 10 is provided by the pins disposed in the second row of the matrix M. The revolution counter 105 advances through one bit for each revo lution.When the data at the input 1 102 of the comparator 110 is equal to that at the input 110, as provided by the second row of the matrix M, the previous situation is repeated.

The cycle proceeds in the same manner.

At the twelfth stage, the sensor 1 12 disposed on the cam drum gives an end-of cycle signal, which sets both the revolution counter 105 and the row or level counter 120 to zero.

By this means, the data of the first row of the matrix M are again read, and the cycle begins again uninterrupted.

The data derived from the first four columns D of the matrix M is fed to the corresponding interfaces 101 and to the outputs.

The case described above shows how the system controls a single knitting machine.

However, the same system with the same matrix can be used to control simultaneously more than one machine, in such a manner that the machines can be stopped at any moment independent of the other machines, and can be started at any moment again independently, so that the machines can thus operate in a non-synchronous manner, each being able to operate out of phase with the others even through using the same program.

To satisfy all these requirements, the entire system can be controlled by means of a microprocessor, which operates such that for each machine the program is effected as in the example given heretofore, and at the same time taking account of the program stage in which each of the machines is operating at any instant. The data is again taken from the single matrix M and is distributed on a timesharing basis to the individual units. There will therefore be individual input clock pulses relative to the number of revolutions and endof-cycle signals for each machine.

Fig. 3 shows schematically the control of five knitting machines C1, C2, C3, C4, C5.

The program is set by the operator on the single matrix A, and each of the five machines executes this program independently and nonsynchronously with respect to the others.

Each machine M,, M2, M3, M4, M5, feeds two distinct signals to the central unit, one being a timing pulse for each revolution of the needle cylinder, and one being a reset signal on completion of each stocking. The central unit feeds to each machine four control signals Cx by way of the contacts of four read relays C. The use of optiosolators B for the two input signals and read relays C for the output signals gives protection against accidental signals in the lines.

The program executed by the central unit scans the in puts from the five machines in sequence, counting the timing pulses and deciding in consequence the control signals to be fed. These control signals are held on bistable elements which act as temporary memories, these memories being refreshed at each scanning cycle, and the control signals are thus reconfirmed even if unvaried.

A routine program checks that the input signals remain stable for a minimum time interval so excluding casual control signals which could become introduced by disturbances present in the conductors feeding the input signals.

The system particularly described replaces the conventional program chain while leaving all the characteristics and the performance of the program (length and data available) unaltered. The system provides increased versatility, because any program change requires neither a long machine down time nor a mechanical operation, as are required in the case of conventional systems. In addition, the system is of small overall size and relatively low cost, and this can be distributed over more than one machine.

Claims (5)

1. An electronic control system for a circular knitting machine including a rotatable needle cylinder, a control cam drum movable stepwise, and actuators, said control system comprising a matrix, removable programming members for programming said matrix, sensor means for determining revolutions of the machine and the end of a knitting cycle, and means associated with the matrix for providing output signals determined by the program for controlling the actuators on the machine.

2. A system as claimed in claim 1, wherein the matrix comprises means defining seats for the removable programming members, said seats being arranged in rows which determine successive stages in the knitting program, and in columns for providing speed control signals, signals for determining stepwise movement of the cam drum, operational control signals and signals for setting required numbers of revolutions.

3. A system as claimed in claim 1 or claim 2, further comprising microprocessor means operative to simultaneously and independently control more than one machine from the same matrix, each machine including sensors and actuators, and output data lines connected to the actuators of each machine, in order to supply the data pertinent to that machine according to the stage in the program at which it is operating.

4. A system as claimed in claim 3, wherein the microprocessor means comprises program memories associated with each of the individual machines being controlled.

5. An electronic control system substantially as hereinbefore described with reference to the accompanying diagrammatic drawings.