METHOD TO MANUFACTURE GRID OF RIFFLES ON INNER SURFACE OF SHELL AND DEVICE FOR ITS REALIZATION Russian patent published in 2017 - IPC B21K21/06 B21D17/00 B21D37/00 B21C37/20 

FIELD: transportation, packaging.

SUBSTANCE: invention relates to special manufacturing of shells with notches in the inner surface to form a grid of riffles. The grid of riffles is made with faces at the angle of 120° relative to riffle top, reduction is carried out with alternating thickness of wall along shell height with taper angle γ=arctg0.5(d_max-d_min)/L, where d_max and d_min - maximum and minimum diameters of a helical ledge, mm; L - shell length in axial direction, mm. In the end of each reduction they perform axial displacement of a stock without its rotation relative to the working insert by the value of 0.1-0.2 of riffle depth, and then the stock is screwed off. In the device the pusher is made with dead cavity. In the cavity of the pusher there is a spring fixed by pins and an instrumental rod capable of axial rotation, between ends of the pusher and the working insert there is a structurally calculated gap h_oc, the shape of the helical ledge surface in the cross section of the working insert is made with the angle at the top of 60° with height of 0.8 of the riffle depth, changing to the surface with the taper cone 120° and total height of the helical ledge, equal to 1.25-1.3 of the riffle depth. The working side surface of the working insert is made as tapered with the taper angle γ.

EFFECT: invention makes it possible to increase quality of manufacturing of a grid of rhombic riffles on inner surface of a shell without burrs from screwing off and to reduce labour intensiveness of the process.

2 cl, 4 dwg