The placement head is the key part of the SMT mounter machine used in SMT processing. After picking up the component, it can automatically correct the position under the control of the correction system, and accurately place the component to the specified position. The development of the placement head is a sign of the progress of the SMT mounter machine. The placement head has evolved from the early single-head mechanical calibration to the multi-head optical calibration, which greatly improves the efficiency of PCBA processing.
After the single-head SMT mounter machine sucks a component, the component is aligned by the mechanical centering mechanism, and a signal is given to the feeder to make the next component enter the suction position. But the mounting speed in this way is very low, usually tt takes 1s to place a chip component. In order to increase the patching speed, people have adopted an increase in the number of placement heads to increase the patching rate.
The fixed multi-head of SMT mounter machine is improved on the basis of single-head, which increases from single-head to 3~6 placement heads. When the fixed multi-head works, mechanical alignment is no longer used. Instead, it is replaced by multiple forms of optical alignment. The placement head absorbs the components separately, and then mounts them in sequence after the alignment. At present, the mounting speed of this type of SMT mounter machine has reached 30,000 components per hour, and the price is low, and it can also be used in combination. As the times progress, the placement head is changed from a mechanical type to a nozzle type, and the technical requirements for the nozzle will increase accordingly.
High-speed SMT mounter machines mostly use a rotary multi-head structure to achieve high-speed placement. At present, the placement speed of this method has reached 45,000 to 50,000 pieces per hour. It only takes about 0.08s to paste a component.
(1) Horizontal rotation-turret mounting head
This kind of SMT mounter machine generally has 12-24 placement heads, each with 5-6 suction nozzles, which can suck and place a variety of components of different sizes. The placement heads are fixed on the turret and can only rotate horizontally.
(2) Vertical rotation-turntable type placement head
Generally, 12 suction nozzles are installed in this SMT mounter machine, and each suction nozzle sucks components during operation. Usually this type of SMT mounter machine reinstalls two or four sets of rotating heads, one of which is in the placement of the head and the other is in the absorption of components, and then exchange functions to achieve the purpose of high-speed placement.
This type of SMT mounter machine consists of 16 independent placement heads. 16 placement heads place components at the same time, which can place 96,000 components per hour, but for each placement head, only 6,000 components per hour are placed, which is only equivalent to the level of a medium-speed machine. Therefore, when working, the placement accuracy is high, the failure rate is small, and the noise is low. For a product to be placed, as long as the components to be placed are allocated to 16 placement heads according to a certain procedure, a balanced combination can be achieved and extremely high speed can be obtained.