SG_FSE_SiplaceHF_HF3_00193901-05_eng - 第390页

1 - 4 S tudent Guide SIPLACE HF/HF3 9 Modular convey or Edition 09/2005 4 9.1.2 C lamping The PCB is lifted for placement of componen ts and pressed up against the PCB clamping rail. When the lif ting table rises the PCB…

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Student Guide SIPLACE HF/HF3

Edition 09/2005 9 Modular conveyor

9 Modular conveyor

9.1 Description of the functions

9.1.1 General

The placement system is supplied with a PCB single conveyor as standard. A dual conveyor is

available as an option. Depending on your requirements, you can choose the left or right conveyor

side as a fixed conveyor side.

In the Processing Area (PA1 or PA2), the PCB board will be clamped from the bottom side against

the fixed holder on the conveyor system.Therfore, the distance between the top of the PCB board

and the placement head will always be the same for every PCB board, regardless of the PCB tick-

ness.This has the following advantages:

– The placement rate is also no longer dependent on the PCB board thickness.

– Furthermore, the fiducial recognition can be optimized, because the distance between the PCB

and the PCB camera is always the same.

– The PCB fiducial shape is optimally imaged on the CCD chip of the PCB camera.

The PCB conveyor is configured in the placement machine so that components up to 6 mm high

can be placed with the 12-segment Collect&Place head or components up to 8.5 mm with the 6-

segment Collect&Place head.

The machine height can be selected to allow the machines to be integrated into lines with a trans-

port height of 830, 900, 930 or 950 mm. The PCB conveyors can communicate with the individual

machines via the SMEMA or the SIEMENS interface.

Movement of the PCBs in the input conveyor, intermediate conveyor and output conveyor is mon-

itored and controlled with light barriers consisting of a sender module and a receiver module:

– When the PCB reaches the placement area, the PCB is detected by a light barrier and the

speed of the conveyor belt is reduced.

– Around 100 ms later, a laser beam detects the leading edge of the PCB as it slowly moves in.

This stops the PCB, which is then clamped from below.

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Student Guide SIPLACE HF/HF3

9 Modular conveyor Edition 09/2005

9.1.2 Clamping

The PCB is lifted for placement of components and pressed up against the PCB clamping rail.

When the lifting table rises the PCB and the complete conveyor drive unit is lifted up to the clamp-

ing position. Therefore the placement level is constant and independent of the thickness of the

PCB.

PCBs up to 450 mm long are clamped in the appropriate placement areas. Clamping does not

take place on the input and output conveyor. PCBs that are more than 450 mm long (max.

610mm) lie on the belts up to a length of 450 mm, but are only supported by the lifting table in the

placement area.

9.1.3 Width adjustment

The width is adjusted by means of a motor as programmed. With the dual conveyor, different

widths are possible for the two conveyor tracks. The width is adjusted with a stepping motor to

allow the new PCB width to be set independently of the other machine components (e.g. Y-axis).

There is no BERO proximity switch on the conveyor rail.

The conveyor rails are fixed by means of a clamping unit on a steel strip.

The PCB width is adjusted via three drivers, they are fitted near the input conveyor, at intermedi-

ate conveyor and near output conveyor.

– The three drivers are moved synchronously by the stepping motor by means of ball screws and

a toothed belt.

– The three drivers are positioned under the conveyor rail to be moved in order to adjust the PCB

width. The precise position is detected by a BERO on the driver.

– The conveyor rail is mechanically connected to the driver by extending the pneumatically-ac-

tuated fixing pins. This disable the clamping of the conveyor rail (at the steel strip).

– Once the new PCB width is reached the fixing pins of the driver are retracted once more. The

conveyor rail is clamped again.

On the dual conveyor, the widths of the conveyor tracks have to be set one after the other (just

one drive for both conveyor tracks). The maximum and minimum PCB widths are protected by limit

switches. If the two conveyor rails of a conveyor track are not parallel, this is automatically cor-

rected during the width adjustment. The three drivers are moved under the fixed conveyor rail and

depened on the average value of the positions of the three drivers will be adjust the moveable con-

veyor rail. The driver that reaches its position under the moveable conveyor rail first fixes the con-

veyor rail. The movement then continues until the second and third drivers have reached their

positions and have also fixed the moveable conveyor rail. The conveyor rail is now conected and

the correct PCB width can be set. The moveable rail is adjusted according the width adjust. units.

The flexible dual conveyor can also be used as a single conveyor by closing up track 2 (max. PCB

format 450 x 450 mm).

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Student Guide SIPLACE HF/HF3

Edition 09/2005 9 Modular conveyor

9.1.4 Checking the PCB position on the conveyor sections

The positions of the PCBs is identified light barriers (sender modules and receiver modules). The

sender light barriers are positioned below the transport belts. They are directed past the transport

belt to the opposite conveyor rail to the receiver above the belt.

The signal from the light barriers stops PCBs in the input conveyors, intermediate conveyors and

output conveyors. These three light barriers can be assembled into four different positions to rec-

ognize also "irregular" circuit boards (PCB with cutouts). In the placement area the light barrier

can be mounted in three differents positions (since HF3), to ensure that the PCB is positioned re-

liably.

In the placement position, the light barrier starts the deceleration of the PCB transport DC motor,

so that a constant time interval (approx. 100ms) for the slow movement to the laser light barrier is

set via software control.

A PCB moving control check the start- and arrival time at the conveyors. This is necessary be-

cause of the PCB-information (bad mark -, PCB recognition) we transfer from PA1 to PA2. The

operator is not allowed to remove PCB’s from the intermediate conveyor.

9.1.5 Stopping the PCB

The PCB in the placement area is recognized by a laser light barrier. The laser beam looks for the

front edge of the board and stops it, as a result there is no shock against the stopper.

The positioning accuracy of the clamped PCB is +/-0.5 mm -precise enough for PCB recognition.

9.1.5.1 "Long Board" option HF

The PCBs have to be clamped twice per placement area (PA) so that each head type (C&P- and

Twin head) can place components over the whole board. This Hardware is mounted on the fixed

conveyor rail.

- a mechanical stopper is integrated

- an intelligent ultrasonic PCB-sensor positioned slightly in front

This is mounted at one position on the fixed transport rail of the intermediate

and output convey-

ors. The ultra sonic sensor is programmed for PCB recognition by placing a PCB above the sensor

and pressing the programming switch for 3 sec.

With this option the standard conveyor light barriers and lasers remain active!

9.1.5.2 "Alignment Pin" option

This option is for unfavorable lenght/width relationship, for cut outs at the leading edge at a PCB

board or for wide and short boards. (This also allow to combine the conveyor systems when the

PCB have a steped leading edge.) Mechanical stopper pin are mounted on a moveable conveyor

rail at the lifting table. If the jumper set for this option on the transport interface, the lifting table

move up, so that the top of the pin is at the height of the board. The laser recognize the PCB board

and the conveyor stops after a defined time and the clamping is completed. The clearance under

the PCB board is reduced to 25mm.