  The generalized summation of divergent trigonometric series, namely by method
of $\sigma_k(r,a)$-factors is considered in this paper. It is proved that such
summation of Fourier series of periodical function $f(t)$ results in the
convolution of this function with kernels $De(r,\alpha,t)$; if the parameter
$r$ is integer, these kernels are polynomial normalized basic $B$-splines of
order $r-1$ $(r=1,2,\ldots)$. Also it is proved that the method of summation
with $\sigma_k(r,a)$-factors is $F$-effective.
