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PCBA Tech
SMT placement machine placement system structure
PCBA Tech
SMT placement machine placement system structure

SMT placement machine placement system structure

2021-11-08
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Author:Downs

The SMT placement machine is a device that accurately places surface mount components on the PCB board by moving the placement head. Its overall structure is divided into three parts, the main part of which is the placement head. From the concept of the Denso robot, the placement head of the placement machine is an intelligent manipulator, which can pick up components according to requirements and accurately Paste on the preset PCB board.

SMT placement machine nozzle:

When the vacuum negative pressure is generated, the suction nozzle is a part that directly contacts the SMT component. The size of the nozzle hole and the shape of the SMT component have a set of very practical suction nozzles for each placement machine. In order for the placement machine to adapt to the placement of different components, it is also equipped with an automatic nozzle replacement device. There is also an elastic compensation buffer mechanism between the suction nozzle and the straw to ensure the protection of the patch components during the picking process and improve the placement rate of the components.

pcb board

Pneumatic solenoid valve for SMT placement machine:

The micro pneumatic solenoid of the placement head is another important component on the placement head. It manages functions such as movement and pick-and-place. With the development of the placement machine, the integrated solenoid valve group also has considerable development. Some single solenoid valves are thicker. Only 10-18 mm. Moreover, the electromagnet drive power is small, and the drive battery of the general circuit can be directly driven.

SMT placement head:

Various types of sensors are installed to enable the various mechanisms of the placement head to work together, effectively coordinating the working status of the placement. When the placement function is determined, the overall structure design of the placement head becomes the key of the placement machine. The placement head is a high-speed moving component. To improve the accuracy, it must reduce its weight and volume, so design a structure with all functions. The patch head is also the focus of patch design.

SMT placement machine components pick and place:

Picking components generally uses vacuum suction nozzles to suck components. It has a simple structure and is easy to maintain. During the pick and place movement, when the suction nozzle moves in the Z direction, the pick and place must be fast and stable. The early movement of the suction nozzle in the Z direction was done by using a micro-cylinder. In the past ten years of use, it was found that the cylinder was easy to wear, short life, and noisy. At present, many new models have selected novel electromechanical transmission rods instead, so that the Z-direction movement state can be controlled, and the comprehensive performance of the Z-direction movement is greatly improved.

Positioning of SMT placement machine components:

The component positioning system of the placement head is an important part of the quality of the placement, and it is also a difficult point in the study of placement technology. When the component is absorbed by the placement component, the component is in an unstable suspension state. Early technology used mechanical claws for passive positioning, which solved the problem of component positioning of early placement machines, but after all, it was a mechanical method. Various errors in mechanical manufacturing directly reflected the quality of component positioning, especially the increase in placement speed. Time, mechanical noise, parts wear and precision life, etc. all limit the progress and development of mechanical positioning jaws.

SMT placement machine component rotation:

When the nozzle head is moving and positioning the device, most of the components perform a quantitative rotation (angle q). First, the installation axis of the component on the board and the axis angle of the component during the movement (q' angle) are corrected. Solve the angle difference between the component on the feeder and the axis of the PCB component pad (q" angle) q=q'+q". The mechanism for correcting component placement angle deviation was controlled by an open-loop stepper motor in the early stage, and the rotation operation was performed through a small synchronous belt. Now some novel placement machines have been replaced by special micro-motors, which greatly improves the performance of the mechanism. In order to improve the placement speed of the placement machine, a combination of multiple nozzles is used in the placement head, and its operating procedures are precisely controlled by a computer.