In some large industries, a robotic arm describing predefined paths in work volume and carrying a welding gun executes automatic welding operations. The deviations in relation to ideal robot arm predefined paths may cause severe distortions in welded parts. The displacement along a straight path must be close to the ideal straight line and the deviations cause a poor quality weld. In this case, the straightness errors in two orthogonal planes crossing the planned welding line can be considered as parameters to predict welding quality. In this work, an approach was used to investigate the performance of a welding cell that requires the determination of path straightness of a robot arm movement using online programming. This approach involves the use of a dial gauge connected to the robot arm and moved over a reference straight standard. The straightness was determined as the range of the measurement errors at each measuring line and was determined in several different locations in work volume. The results obtained showed that the different regions in work volume promote the change in weld quality and error compensation may be applied to improve the accuracy in welding operations.

The use of robotized welding to achieve better quality has demanded research of new technologies to integrate and test the systems. The complete control of a flexible manufacturing cell involves perfect task synchronisation among all of its robots and equipment. Off-line programming provides an essential link between CAD and CAM. The development of off-line programming systems should result in greater use of robots and accelerate the implementation of flexible manufacturing systems (FMS). It also offers an alternative for complex automated production lines and should allow rapid response to changing product/process issues. This article describes some features of graphic simulation and off-line programming focusing on its applications to robotized welding.

We report specific-heat measurements at temperatures in the range between 0.07 and 1.37 K of the isostructural copper-amino-acid isomer complexes Cu(L-but)2 and Cu(D, L-but)2 [Cu(H2NCHCH2CH3CO2)2], which have copper ions in layers. No peaks that could indicate magnetic phase transitions are seen down to 0.07 K. The observed temperature dependences agree with the predictions of existing models for Heisenberg antiferromagnetic chains with nearest-neighbor isotropic exchange interactions. Values of the exchange-coupling parameter between copper ions of J/k = (-0.64 +/- 0.01) and (-0.84 +/- 0.01) K are obtained from the data in Cu(L-but)2 and Cu(D,L-but)2, respectively. The one-dimensional behavior is interpreted as a consequence of predominant superexchange interactions connecting copper atoms along the b axis through pairs of hydrogen bonds. Our results are compared with those obtained from the analysis of electron-paramagnetic-resonance-linewidth data for Cu(L-but)2 and Cu(D,L)-but)2, as well as with results from measurements in other copper-amino-acid complexes.

A specific heat calorimeter for the temperature range 0.07–1.3 K with a novel sample support of four commercial pencil leads is described. It is shown that this support substantially reduces the vibrational heat input to the sample assembly. The thermal shield of the calorimeter is vacuum tight to allow measurements with gas adsorbing samples. We estimate and derive expressions for the temperature dependence of the thermal conductances of the AuCu thermal link and of the pencil leads support.

The variable-range hopping expression R(T)=R0e(T0/T)α used to describe data for carbon and thick film chip resistors is discussed. For both kinds of resistors it was found that 14 ≤ α ≤ 12, although for the thick film resistors the applicability of models originally used in doped semiconductors is still under discussion. The use of these resistors as thermometers in heat capacity measurements in the range 0.05–1.5 K is also discussed.

The specific heat as a function of temperature of Stycast 1266 was measured in the range from 0.1 to 1 K. The results are described, within 2%, by the expression c(T)=aT+bT3+cT5, where a=2.91(6) μJ/g K2, b=15.7(5) μJ/g K4, and c=8.98(0) μJ/g K6. The linear and cubic terms were related to the model of two-level systems and to the Debye specific heat, respectively. The origin of the T5 contribution remains unexplained.