Tube perforator
SUMMARY OF THE INVENTION 
     In hoods, such as are employed by sand blasters and painters in confined quarters, such as the inside of a storage tank, cool air is supplied to the inside of the hood during the work, so that the user will be provided with clean air, a cooling agent, and the shield of the hood will be free of condensation. This is customarily accomplished by introducing cool air into the hood through a perforated hose. Because the discharge openings are so close to the ears of the user, the sound of air passing through these openings can be very annoying to the hood user. To allow the free, silent passage of air from the hose into the hood, the inside wall of the hose is maintained smooth, with the lips of the opening drawn outwardly. The device described herein forms such openings, providing a base member having a groove to receive the hose to be perforated, and an upper member secured to the base member and constantly urged away from the base member, with a lever operated eccentric means adapted to move against the upper member to force same against the lower member. The upper member has a plurality of needles vertically adjustable in the upper member and extending downwardly beneath the upper member, the extended ends of said needles having a rounded head, substantially ovoid in shape terminating in a sharp point positioned to penetrate a hose resting on the base member, and forcing the head of the needle through one wall of the hose, and, if desired, the point of the needle also passing through the opposing wall of the hose, and the needle then withdrawn, the ovoid head of the needle drawing the peripheral edges of each opening so formed outwardly, leaving the inside wall of the hose smooth. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front elevational view of the device, with a tube to be perforated mounted therein. 
     FIG. 2 is a cross sectional side elevational view, taken on the line 2--2 of FIG. 1, showing the upper member in raised position, with a tube mounted in the lower member, illustrating the first position of the perforating operation. 
     FIG. 3 is a cross sectional side elevational view, taken on the same line as FIG. 2, with the upper member in lowered position, illustrating the second position of the perforating operation, and 
     FIG. 4 is a fragmentary cross sectional side elevational view illustrating the third position of the perforating operation. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the drawings, the numeral 1 designates a lower member formed of a rigid material, such as steel, and of a rectangular shape, in which a groove 2 is formed, which said groove extends longitudinally of the member 1, and whose side walls are vertical with an enlarged semi-circular area 3 midway between the vertical ends of said groove, adapted to receive a tube to be perforated, as 4. Pins 5, 5 are mounted in the lower member 1, and extend upwardly from the top surface of the lower member. Spring mounting chambers 6, 6 are formed in the base 1, to receive the springs 7, 7 which seat in said chambers and extend upwardly beyond the top surface of the lower member. 
     A pair of upstanding support members 8, 8 are secured to the lower member 1 as by the bolts 9, 9. An upper member 10, rectangular in shape and similar in dimensions to the lower member 1, is provided with ports 11, 11 formed therein and positioned to receive the guide pins 5, 5. A row of ports extends longitudinally of the upper member 10 and each port extends vertically through the upper member, the upper portion 12 of said ports being enlarged and the lower portion 13 being threaded. A needle 15 has its upper portion enlarged and threaded as 14 and may be mounted in said threaded portion 13 of the port. The upper end of the needle 15 is shaped to receive an Allen wrench for adjusting the needle, and the lower end of the needle has an ovoid head, as 16, terminating in a sharp point. 
     A shaft 17 is transversely mounted in the upper ends of said supporting members 8, 8, and the eccentric cam 18 is pivotally mounted on said shaft 17. A threaded port 20, in the face of said cam 18, receives the externally threaded handle 21. 
     The hose to be perforated is mounted in the groove 3, in the enlarged side wall area, and the needles 15 are adjusted in the ports 12 to the position desired. If only a single wall perforation is desired, the needles will be positioned to penetrate only that distance. The row of ports 12 will consist of a plurality of ports in close proximity to each other, and so many of the ports as may be desired, may be may be employed. Usually the needles are spaced to provide pairs of perforations in close proximity. If a double perforation is desired, the needles may be adjusted in the ports 12 to penetrate both walls upon termination of the down stroke. As the lower penetration is made, the margins of the perforations will be forced outwardly, the area of the groove beneath the enlarged area receiving the point of the needle, and as the needle is withdrawn, the rounded head of the needle will similarly draw the material around the margin of each perforation outwardly, leaving the inside wall of the tube without projections. The springs 7 urge the upper member 10 constantly into raised position, and the penetration is accomplished by rotating the cam against the top surface of the upper member, forcing the upper member downwardly, and the downward movement being limited by the lower member. 
     It is obvious that many types of tube perforations may be accomplished by this device, and that the manual means of lowering and raising the penetrating means may be replaced with electronic means, if desired. 
     The method taught herein is in the formation of perforations in tubes, and the like, by penetrating the side walls of the tube to be perforated, and in removing the needle from the tube, withdrawing the peripheral margins of the perforations, permitting the excess material to protrude outwardly, leaving the interior wall of the tube smooth.