Apparatus for making holes in webs of wrapping material for cigarettes

Abstract

Apparatus for making holes in a running web of wrapping material in a filter tipping machine has a housing which defines an elongated passage for the running web and contains rows of first and second electrodes which are disposed at the opposite sides of the passage and define spark gaps forming part of the passage. When the web is drawn through the passage and the electrodes receive high voltage impulses from the secondary winding of a transformer, sparks which are caused to jump across the gaps burn holes in the running web with attendant heating of the electrodes as well as development of dust and ozone. The intake end of a conduit is connected to the housing to draw through the passage a stream of cool atmospheric air when a blower which is connected to the discharge end of the conduit is in operation. The air stream cools the electrodes to thereby prolong their useful life and to reduce the likelihood of charring of the web. Furthermore, the air stream withdraws from the housing particles of dust as well as ozone. The particles of dust are intercepted by a first filter which is installed in the conduit ahead of a second filter for separation of ozone so that dust cannot contaminate the second filter and the second filter prevents the ozone from reaching and corroding the blower.