Design process of executive elements in stroke mechanisms based on rammer’s deformations and stress modeling

The article deals with the strength calculation issues of products by example of rammer under short-term loads in hammer drill. Based on finite element analysis’ results of the rammer geometrical model, it is proposed to select a material with a strength limit significantly exceeding the allowable residual stresses inside the rammer. The harmonic analysis allows us to estimate the rammer’s strength. The dynamic coefficient may be calculated by the use of Vibran 2.0 device (amplitude and signal frequency) and by calculation results of the maximum displacement. The FreeCAD software package was used for this. It allows to create internal scripts to automatically search for the optimal design parameters. A method of determining mechanism’s static load and its dynamic coefficient under periodic impact loads has been developed. Static loads calculations and harmonic analysis according to the developed method allow to determine structural strength of the product, to select the rammer’s material and to find the dynamic coefficient (which takes into account the stroke loads in calculations). The pro-posed calculation method may be used not only to solve the describing problem, but also for a whole class of problems related to stroke loading, where such parameters as application time of force or duration time of force’s impulse are important.