Tripod “LSZ 60”

A cost-efficient solution in a modular design.

For mechanical engineers who require a suitable tripod robot for their pick-and-place tasks or sorting applications there are normally only complete solutions including controls available.

This results in both higher cost and the necessity to adapt the interfaces between the application control used and the controls of the positioning system. Bahr Modultechnik is now paving new ways with its tailorable tripod system, which consists of standard components and uses linear positioning technology.

Increased demand for tripod positioning systems

Bahr Modultechnik is a leading global full-range supplier of modular positioning systems specialising in the development and design of linear positioning technology with spindle drives, rack and pinion drives or belt drives. Due to their modular design, these products can be adjusted very easily to the most different applications. “Around 80 per cent of our customers produce special-purpose machines,” said Dirk Bahr, Head of Design at Bahr Modultechnik. “The increasingly challenging application requirements result in portal robots reaching their design limits. Therefore the demand for tripod positioning systems has dramatically increased recently, as they are much faster due to their design.” To meet this demand, Bahr has designed a flexible and powerful tripod system using only standard components and linear positioning axes with belt drive. This has resulted in a very economical alternative compared to the more complex products offered by the competition. In addition, the Bahr tripod system can be combined with controls of any make. “In principle, the tripod comprises only the complete mechanical construction, consisting of three positioning axes and the articulated brackets,” Dirk Bahr explained. “This system can be provided by our customers with the controls and motors preferred by them.”

Special design features of the Bahr tripod system

The parallel kinematics of Bahr’s tripod system is based on the interaction of three belt-driven positioning axes of the LSZ 60 series. The clevis arms, which are made of a light-weight, highly robust carbon fibre plastic or aluminium, are mounted directly to the carriages of the positioning axes by means of joints. Thanks to their special dimensions and due to the use of only one belt deflection unit, the carriages can be moved along nearly the whole length of the aluminium square profiles and thus achieve an increased degree of freedom of the rod mechanics.

Simple, flexible, efficient, affordable: system simplification à la Bahr

The direct transfer of kinematics from the carriage to the clevis arms results in a system that is significantly simpler and does not need any gears. In addition, the linearly guided rod arrangement requires less joints than conventional tripod positioners – which is a clear advantage regarding stability, since the clevis arm joints can become weak points under high loads or in case of impacts acting on the system. The linkage between the rod mechanics and the gripper base plate is realised by Bahr Modultechnik either via ball bearing joints or by means of a simpler and more cost-effective ball head bearing, in order to achieve a higher stability for the latter variant.
Similar to the profiles of the positioning axes, which can be delivered in any length – i. e. sold „by the meter“ – Bahr Modultechnik also uses a cost-reducing simplification for the construction of the carriages as well. The basic structure of the carriages is produced by cutting the required width dimensions from an aluminium square profile. Subsequently, Bahr machines the milled profile pieces in standardised procedures.

Space-saving construction

Thanks to the LSZ 60 positioning axes, the systems are very space-saving. The profiles, which are available in any length, can be combined with other T-nut profiles, so that the user can provide the system with additional parts very easily. The toothed belt disc is installed with two coupling claws as a standard, so that drive motors of any make can be integrated.