Patent GB-1223059-A (GB)
Title: Apparatus for making perforations in corrugated tubes
IPC: B21D28/28
Filed: 1968-12-09
Abstract: 1,223,059. Perforating corrugated tubes. A. KIRCHNEK, [trading as FRANKISCHE ISOLIERROHR -UND METALLWARENWERKE KIRCHNER GEB.]. 9 Dec., 1968 [28 March, 1968], No. 58310/68. Heading B5A. [Also in Division H2] A circumferentially or helically corrugated thermoplastic tube 1, Fig. 1, is perforated at the ridges and/or troughs thereof e.g. for use as drain pipes, by cutting tools 7 comprising a saw toothed cutting edge extending around the periphery of the front end of the tool, and with the inner flank of the tool inclining rearwardly to define a recessed end. The tools 7 are supported by carrier means 6 actuated by drive means effecting recurring penetration of the tools 7 along the tube 1 as this is advanced by a feeding means. In the Fig. 1 embodiment, wherein the tube 1 is intermittently advanced, the carrier 6 is reciprocated by a crank drive 8, 10, 11 from gearing 13, 14 driven from a sprocket 15 by a variable-speed motor. The tube feeding means comprises a pair or more of wheels e.g. 26<SP>1</SP>, each formed with a semicircular recess 28, which co-operate to embrace the tube 1, the surface depressions 30 whereof are engaged by projections 29. The feeding means is intermittently actuated by a bevel gear drive, to the shaft of one of the wheels, from a disc 19 provided with projecting follower pins 20 which are intermittently transversed along a finite length cam groove 18 on a cylinder cam 17, which is provided with elements 21 which intermittently guide the pins 20 into, and restrain them at the outlet of, the groove 18. The synchronization of the carrier and feeding mechanism movements may be varied by an angularly adjustable connection in the drive shaft 16 to the cam 17. The tube 1 may be supported by lateral members at the perforating station if only two opposed carriers 6 are employed. The carriers 6 may also be displaceable to perforate and move with the tube 1 as this is being intermittently advanced, and may also be actuated pneumatically, hydraulically, by a toggle mechanism, or electromagnetically. The tube feed mechanism may be driven independently of the carrier mechanism. The tube may be supported internally at the perforating station by a hollow mandrel which is apertured to permit passage of the perforating tools. In one embodiment, Fig. 3 (not shown), the mandrel is supported against longitudinal and rotational displacement by the location of oppositely bent ends thereof against pairs of guide wheels, located before and after the perforating station and between which the tube passes. In another embodiment, Figs. 15- 17 (not shown), the mandrel is supported by magnetic levitation (see Division H2). The perforating tools, Figs. 4-8 (not shown), comprise an elongated cutting end provided with rectilinear or curved saw-toothed cutting configurations projecting around the periphery thereof, and the teeth at one edge of the cutting tool end may project more than at the other edge to provide a sequential perforation of the tube. The recessed nature of the cutting end of the tool within the surrounding cutting edge may entrap the cut portion of the tube. In the Fig. 11 embodiment, the feeding means comprises a series of ribs 87 at either side of each of one, a pair of, or more rotary wheels 80, supporting perforating tools 90 between the series of ribs. Each tool 90 is secured in a holder 93 attached to a wheel 80 at pivots 95 permitting aligning displacement between pins 96, against the action of springs 97. The tools 90 may also be radially displaceable with respect to wheel 80 by cams or plungers, against the bias of springs, and may also be provided with a parallel mechanism comprising pairs of rotary eccentric rings whereby the axis of the tool is maintained normal to the direction of movement of the tube. The tools 90 and ribs 97 may also be provided on an endless conveyer. In the Fig. 13 embodiment, the tools 100 are displaceably mounted on spaced apart carriers within links 101, which are connected to form one or more endless chains 102 and are each provided with a series of tube feeding ribs 103. Each carrier is actuated to displace the tools 100 to perforate the tube, preferably against a spring bias, by follower rollers 105 thereof engaging stationary cam tracks 109, 110. Alternatively the carriers may be retracted by cams acting against a spring bias. The apparatus of Fig. 13 may operate immediately after a tube forming station, the forming mandrel whereof may project to provide support at the perforating station. Shaping members may also be provided which engage the tube immediately prior to the perforating operation to ensure that a correct configuration thereof is maintained.