Quella che segue è la specifica finale generata da PRECMA S.r.l. dell'alimentatore di telaio ALFA 6, la cui elettronica è stata sviluppata interamente da PRECMA S.r.l. per conto della SAVI S.p.A.
La specifica e' qui presentata esclusivamente come esempio di nostra progettazione e documentazione

This is the PRECMA S.r.l. specifications for ALFA 6 prototypes, made for SAVI S.p.A.

The feeder electronic is composed of four printed circuit boards including some hibrid circuits and three microcontrollers:

One power switching hibrid circuit (12V; 5V)
One watch dog and phase doubler hibrid circuit
One power MOS driver hibrid circuit
One microcontroller for three-phase waves production
One microcontroller for sensoring, speed control and user interface
One microcontroller for RS-232 communication with external devices

Summary

Feeder Description

The Load Function
The Ready Signal

Feeder Functions Setting

Length To Wind
Brake Power
Single Run
Feeder Speed
Wound Length
Winding Time
Error Detect

SYNC signal specifications
Data for SYNC input
ERROR Signal Specifications
Data for ERROR output
Power Requirements

Feeder Description

ALFA 6 is a special weft feeder for very long weaving machines.

ALFA 6 must wind up the correct yarn length before the waving machine pick start.
 

Description	Min	Max
Yarn	Mono	Mono
Yarn Diameter	0.5mm	0.9mm
Weaving Machine Length	6m	12.20m
Weaving Machine Kind	Projectile	Projectile
Weaving Machine Speed (rpm)	n. d.	80

Two ALFA 6 run on the same weaving machine at the same time, and the weaving machine gets the yarn one pick from one of them and one pick from the other (alternative). It is also possible to use three ALFA 6 at the same time, if a very high precision in winding is required.

When it is running, ALFA 6 winds up the correct yarn length every "Feeder Cycle", that can correspond to two or three weaving machine revolutions, depending from the SYNC signal.
 
 

The LOAD switch is for a particular function of ALFA 6: if you want the feeder to wind up the yarn every time you turn ON the ON/OFF switch (LOAD function), the LOAD switch must be positioned UP. If you don't want that, the LOAD switch must be positioned DOWN.

You may want to set the LOAD function "ON" on the feeder from which the weaving machine gets the first pick when it starts, and you may not want it on the other feeders.
 
 

The Ready Signal

The READY signal indicates to the weaving machine that it is possible to get yarn from the feeder.

Note that READY is OFF (= Low = 0V open collector PNP) when the feeder is winding up the yarn, and is ON (= High = 12V I _out Max = 10mA) when the winding ends. As the weaving machine must not activate the rear brake until the end of the feeder winding, it can use the READY signal to prevent it.

Special Feeder Connections

On the rear side of ALFA 6 there are:

One Amp-Latch 10 pin connector
One green 4 pin terminal connector

The green terminal connector must be connected to the weaving machine, and it is the optically isolated input line for the synchronisation signal (SYNC): see "SYNC signal specifications" section.

The green terminal connector brings also the ERROR signal (pin 2 and 3):
 

Signal Description	Terminal Connector Pin
SYNC Signal GND	1
ERROR Signal Contact (relay output contact)	2
ERROR Signal Contact (relay output contact)	3
SYNC Signal Input	4

Feeder Functions Setting

It is possible to adjust the feeder winding parameters using a special device called "IA6", that can be connected to ALFA 6 and shows the settings on the LCD display.

IA6 device must be unplugged from ALFA 6 after parameter setting. ALFA 6 may not work correctly if IA6 is plugged during normal weaving operation.

Settings can be changed using the "UP" and "DOWN" keys on the front panel of IA6. IA6 doesn't works if it is not connected to ALFA 6.

With the "SELECT" key it is possible to choose from various functions:

Length To Wind (Read/Write)
Brake Power (Read/Write)
Single Run (Command)
Feeder Speed (Read)
Wound Length (Read)
Winding Time (Read/Write)
Error Detect (Read/Write)

This function is used to set the length of the yarn that the feeder will wind up every cycle.

The LCD display shows alternatively "Length To Wind" and the set value. It is possible to change the set value using the UP and DOWN keys. Min. value is 600cm, Max value is 1220cm.

If you try to set a value over the range, a "Comm Error" occurs.
 
 

Brake Power

This function is used to set the power of the front yarn brake.

The LCD display shows alternatively "Set Brake Power" and the set value. It is possible to change the set value using the UP and DOWN keys. Min. value is "25% Max", Max value is "100% Max", default value is "50% Max". Set lower or higher only if it is really necessary.
 
 

Single Run

This function can be used to try a feeder winding cycle; it is the same as the LOAD function, but you don't need to use the ON/OFF switch and it doesn't use the front yarn brake. If the ON/OFF switch is in the position OFF, this function doesn't work.

The LCD display shows alternatively "Single Run" and "Up Key To Start"; if you press the UP key and the ON/OFF switch is in the position ON the feeder starts a winding cycle. DOWN key is not used.
 
 

Feeder Speed

This function reads the feeder number of winding cycles per minute (cycles/min.), that may correspond to the waving machine speed (rpm) divided by the number of feeders connected. For example, if you have a 70rpm waving machine with 2 feeders connected 1:1, the feeder speed is 70/2 = 35 cycles/min.

The LCD display shows alternatively "Feeder Speed" and the read value; UP and DOWN keys are not used. If you try to read that value immediately after a power on, and before starting weaving, a "Comm Error" occurs.
 
 

Wound Length

This function reads the length of the yarn that the feeder has wound up during the last feeder cycle up to that moment. The LCD display shows alternatively "Feeder Speed" and "Up Key To Read"; DOWN key is not used. If you press the UP key you will see on the display the wound yarn length in that moment. The wound yarn length value is cleared at the beginning of each feeder cycle.
 
 

Winding Time

This function is used to set the winding cycle time.

The LCD display shows alternatively "Winding Time" and the set value. It is possible to change the set value using the UP and DOWN keys. Possible values are SHORT, MEDIUM and LONG. Winding length precision is max with the LONG value set, but the feeder will need more time to wind up the correct yarn length.

SHORT winding time is useful with high weaving machine speed (70-80 rpm) working with only two ALFA 6 at the same time.
MEDIUM winding time is useful with low weaving machine speed (60-70 rpm) working with only two ALFA 6 at the same time.
LONG winding time useful with all weaving machine speeds working with three ALFA 6 at the same time.

This function can be used to signal winding errors to the weaving machine, using the ERROR line (see "ERROR Signal Specifications" section).

It is possible to change the settings (DISABLED, MIN, MEDIUM, MAX) using IA6:

MIN signals errors -1 step +2 step
MEDIUM signals errors -2 step +4 step
MAX signals errors -3 step +6 step
DISABLED no error detection

Specifications
 
 

SYNC signal specifications

The SYNC signal must correspond to the diagram (ON = 270° = from 90° to 360°) when working with two ALFA 6. When working with three ALFA 6, SYNC signal will stay OFF for 360° more than in the diagram each winding cycle.

The green terminal connector on the rear side of ALFA 6 must be connected to the weaving machine, and it is the optically isolated input line for the synchronisation signal (SYNC):

Pin 1 (left) = 0V = GND
Pin 4 (right) = SYNC signal

SYNC= OFF = `0' signal correspond to "Circular Front Yarn Brake Closed"

Data for SYNC input

Floating yes (optocoupler)

SYNC Input Voltage

- Rated Value 24V dc

- At `0' signal 0V to 5V dc

- At `1' signal 13V to 30V dc

Input Current

- At `1' signal Typical 8.5mA (at 24V dc)

Residual current for `0' signal < 1.5mA

Note that the "Feeder Winding" time may result different (longer or shorter) than in diagram (fig. 5); please refer to the section "Winding Time Limits" for accurately timing the Weaving Machine Cycle.

With shorter "Feeder Winding" time there may be no problems, but with longer "Feeder Winding" time the weaving machine must take care not to activate the yarn rear brake until the end of feeder winding, that can occur even in the first part of the "Pick Time".

The READY signal can be used from the waving machine to know when it is possible to brake the yarn with the rear brake. The weaving machine must not activate the rear brake until the end of feeder winding.

ERROR Signal Specifications

ERROR output contact close when a feeders winding error is detected.

Pin 2 = Contact (relay output contact)
Pin 3 = Contact (relay output contact)

Floating yes (relay)

Continuous Current 50mA at 30Vdc

PTC contact protection yes (65W 55mA)

Power Requirements

1000 VA
48V