Understanding and Using Linear Transfer Systems

The automated assembly of complex end products can often only be mapped on linear platforms, which accommodate different process times and a high number of processing stations. Linear transfer systems are particularly well-suited for such applications. 

 

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WEISS has four linear transfer systems with a total of five different drive types in its portfolio. Despite the high degree of freedom offered by each individual linear transfer system, there are differences in how they are used and designed. WEISS transfer solutions are characterized by a high level of precision and reliability. They are supplied as a complete solution: pre-configured, pre-parameterized and pre-commissioned. Machine manufacturers and system operators thus save valuable time and resources during the design phase, as well as later during start-up. All linear transfer systems are consistently built in a modular design. It is easy to integrate them into the higher-level system because WEISS understands its linear transfer systems as part of a complete assembly line. 

Link conveyor systems – effective for uniform processes
In the WEISS portfolio, process steps with the same time requirement can be realized on the LS Link. The link conveyor system is used in the electronics and plastics industry for clipping components, in the cosmetics industry for filling containers, for filling construction chemicals like sealing foams into cartridges, and more. The reduced system complexity and high level of reliability of LS Link ensure a high level of productivity and economic efficiency, particularly in mass and large-scale series production. 

The precision drive concept of LS Link consists of a servo motor, backlash-free precision planetary gears and a well-designed guide. When the link conveyor system is installed vertically, the guide concept enables workpiece carriers to be loaded with up to 50 kilograms. The robust design provides stability and handles process forces of up to 1,000 newtons. The drive system and transport chain are connected in a highly-precise manner. The well-designed guide and positioning concept enables the workpiece carriers to be positioned exactly in relation to each other and also in relation to processing or machining stations.

The positioning accuracy is ± 0.05 millimeters here. With a motion time of under 0.2 seconds at feeds of up to 200 millimeters, LS Link is fast, efficient and flexible. It can approach any position and any feed required. Thanks to the guide concept, the processing stations can be arranged in the straight areas of LS Link as well as in the redirection areas. This increases its adaptability to the higher-level assembly line and to the customer application.

Regardless of the chain link length, the overall transfer system width is always 454.4 millimeters. Since a total of four chain link lengths are available to choose from, system and machine manufacturers are free to design the assembly or transport processes. The link conveyor system can also be installed vertically as well as horizontally – entirely as the production process requires. The transport chain can be separated into smaller parts upon request, which facilitates the assembly of long systems.

Cam drive – precise and robust
For the LS 280 fixed-station linear transfer system, WEISS applied the drive concept of its rotary indexing tables to linear transport. A high-precision cam enables the motion profile for linear assembly automation. Its positioning accuracy is ± 0.03 millimeters in the X and Y directions. To achieve this level of accuracy, no additional stop or indexer modules are needed. All classic assembly lines can be built with LS 280 as the basis. Process sequences with high quantities and pre-defined strokes can be implemented optimally.

Common fields of application are found in the consumer goods industry or the production of beauty or healthcare products. The ability to load the workpiece carrier with up to four kilograms is ideal for these purposes. With the frequency-controlled belt drive, the speed of the workpiece carrier when approaching the cam action is reduced compared to normal trans-port. This prevents vibrations to the customer product. LS 280 makes it possible to combine different cycle strokes within one system. 

Direct-drive solutions – maximum flexibility 
Batch changes are often made in consumer goods, electronic products, the pharmaceutical in-dustry and battery pack assembly. Systems that map different process times on one platform and can be quickly and reliably converted are advantageous here. LS One is the ideal basis for these assembly lines. LS One consists of only three segments: two motor segments and a redirection module. This simple structure means greater design freedom: the system can be extended or shortened at any time by adding or removing individual elements. The linear motor, the control system and the basic programming of LS One also guarantee a high level of reconfigurability and quick, simple adjustment to new processes. 

The direct-drive linear transfer system is specially designed for tasks that demand the highest levels of precision and flexibility. It demonstrates its flexibility in the motion of the workpiece carrier as early as the setup phase. Each workpiece carrier can be controlled and moved individually. Grouping procedures and buffer processes are therefore easy to implement in a wide range of constellations. LS One features a positioning accuracy of ± 0.03 millimeters in the X and Y directions. A rolling element-based high-precision track made of solid metal supports the precision of the linear motors. The workpiece carriers are pretensioned and guided along a rail. They are also supported by a rolling element-based, metallic flat guide. 

Alongside the stop positions of the workpiece carriers, the acceleration, speed and direction of motion are also freely programmable. The workpiece carriers are designed for loads of up to five kilograms and can handle process forces of up to 300 newtons without support. 

The entire LS One system is prepared and parameterized in advance by WEISS at the factory. This saves up to 30 percent of system operators’ time during start-up and enables a quick start to production.

Combined drive types – for nearly impossible tasks
The LS Hybrid linear transfer system combines several drive types in one system: a cam drive, a belt section and a linear motor segment are used in combination to map the most complex processes with high process forces. Depending on the end product, different process times and high-precision, free motion profiles must be combined in the assembly process. Assembly lines in the automotive environment, the electronic device assembly sector and in complex and multi-step assembly processes in the consumer goods sector often meet these requirements. 

Thanks to its design, LS Hybrid can be loaded with workpieces weighing up to ten kilograms. LS Hybrid users achieve the highest degree of positioning accuracy of ± 0.02 millimeters in the X direction and ± 0.03 millimeters in the Y and Z directions on the linear motor segment. Several drive types can be combined on the transfer system, which can handle process forces of up to 1,000 N. With LS Hybrid, it is possible to print plastic parts or press in electronic components, for example.

Control system as part of the solution
As a manufacturer of automation components, WEISS places great value on the ability to integrate and combine its solutions with other systems, especially on the software side. While LS Link is equipped with a PLC communication module that can easily be integrated into the higher-level system control, the three other linear transfer systems are operated with W.A.S., the WEISS application software. It supports quick and simple start-up and seamless connection to the customer PLC. The parameter set of the transfer solutions is individually configured and optimized before delivery to the customer. 

Operators can fully concentrate on their process and the settings it requires. The monitoring functions integrated into the control system ensure the highest level of operational safety. In principle, W.A.S. can be used without in-depth programming knowledge and is easy to integrate into the higher-level system control. With LS One as a linear motor-driven system, four motion scenarios are already prepared for the workpiece carriers, for example. Users only have to enter the application-specific parameters for acceleration, speed and the direction of motion.