Sieb & Meyer has realized a frequency inverter with a special housing design for Schmoll, which is precisely tailored to the existing installation conditions and the assembly process of the PCB drilling machines. The inverter enables sensorless operation of up to eight high-speed spindles.
Schmoll Maschinen GmbH builds production machines for electronics manufacturing and micromachining. The portfolio includes all relevant process steps for mechanical and laser micromachining. The production capacity of the machines can be increased through partial or full automation. "Our experience in laser technology is highly valued in the PCB industry and related sectors," says Marcus Winterschladen, Technical Director at Schmoll Maschinen GmbH. "We are also one of the world's leading providers of production solutions for the electronics industry."
PCB drilling systems for mass production
The central frequency inverter in the PCB drilling machines must be able to operate up to eight high-speed spindles in the speed range up to 480,000 rpm without sensorsInthe PCB processing sector, Schmoll builds PCB drilling machines for mass production as basic machines for maximum productivity. At the top end of this class is the Speedmaster series, in which the most powerful drilling spindles are used: The spectrum ranges from spindles with 60,000 rpm to versions with a maximum of 300,000 rpm. The different spindle types allow a wide range of customer requirements to be covered.
Linear motors are used to drive the traversing axes in the XY direction. Together with a base body made of high-quality granite, high basic accuracy and, above all, process reliability are achieved. At the same time, low energy and maintenance costs are guaranteed. Depending on the configuration and size of the panels, machines with typically 5 or 6 spindles can be realized - up to 8 are possible. Customer-specific adaptation of the assemblies is possible.
High-speed FU for multi-spindle operation
In the PCB drilling machines, which are equipped with T180 or T200 asynchronous spindles, Schmoll installs a customized frequency inverter from the Lüneburg-based manufacturer Sieb & Meyer. "The central frequency inverter must be able to operate up to eight high-speed spindles in the speed range up to 480,000 rpm without sensors," says Michael Schulz, Key Account Manager CNC Europe / USA, explaining the customer's requirements. "In addition, the frequency inverter was to be supplied with power via the DC link of the existing drive package."
The FC2 series device, which is characterized by a device topology with a regulated DC link, served as the basis for the customer-specific solution. Using pulse amplitude modulation (PAM), this makes it possible to drive low-inductance asynchronous motors without additional motor chokes up to an output frequency of 8000 Hz (480,000 rpm), while ensuring low motor heating and dynamic speed control.
Proven standard individually adapted
The parallel operation of up to 8 asynchronous motors and the separate evaluation of the temperature sensors are already included in the scope of the standard device. The technicians in Lüneburg adapted the power supply electronics and the design of the device to the machine conditions. This reduced both the installation space and the amount of wiring required. "Unlike the standard version, the power supply unit is not integrated into the device, making the housing more compact," says Schulz. "This makes it possible to install the frequency inverter directly in the drive package - in this case next to the servo amplifiers. This means that the central supply voltage of up to 350 VDC available in the machine can also be used." Innovations and changes are incorporated into the basic software of the series products in close consultation with Schmoll. Important for the user: The frequency inverters can be easily parameterized via software. This means that the machines can be easily converted to other spindle types if necessary.
The FC2 series device, which has a device topology with a regulated DC link, served as the basis for the customer-specific solution
The design of the FC2 was adapted to Schmoll's machine conditions
The compact system is adapted to the available installation space and is produced in series by Sieb & Meyer - this means stable costs and high availability of the components, whereby Schmoll can react flexibly to fluctuations in demand at any time. This customized product can therefore be offered to the customer with a convincing price-performance ratio. At Schmoll, the customized FC2 can also be installed in the machine in just a few simple steps without any additional components.
"The frequency converters allow the spindles to run very smoothly, which contributes to the good drilling results of the machines," says Winterschladen. "The pulling power and performance are also always optimal." In addition to the technical advantages, the technician praises the good cooperation, high level of expertise and professional advice. The collaboration between the partners will therefore continue.
