US 4,057,357 A · Chipless shell cutter for large diameter plastic pipe

Abstract

A rotatable shell cutter member for cutting a hole in large diameter and thick wall plastic pipe. The shell cutter member is rotated and advanced with a positive predetermined lead against the plastic pipe and it first forms a hole in the plastic pipe by cutting and retaining a coupon therefrom and it further progressively enlarges the hole to a diameter equal to or slightly greater than the overall outside diameter of the shell cutter member. The chips initially cut from the plastic pipe in cutting the coupon are discharged upwardly and inwardly of the shell cutter member above the coupon being cut and, when the shell cutter member with its cutting edge in constant cutting engagement with the pipe begins cutting a continuous chip cut, it is also discharged upwardly and inwardly of the shell cutter member. The cutter blade for cutting the plastic pipe is detachably secured to the body member of the shell cutter member so that it may be easily removed and replaced or resharpened and cleaned when the situation requires such action. A drilling machine powered by a compressed air motor, electric motor or gasoline powered engine may be used to rotate and advance the shell cutter member although hand operated drilling machines with positive feed advance may also be used.

Claims23

Dependent claims

A rotatable shell cutter member for cutting a hole in large diameter plastic pipe by cutting a coupon to form a hole and enlarging the formed hole when the shell cutter member is positively advanced against the pipe a predetermined distance per rotation of the same, said shell cutter member comprising:

a metal hollow body member closed at one end and open at its other end to define a chamber for chips cut from said pipe, said body member having a cylindrical portion terminating at the said other end in a frusto-conical end portion;
a generally lengthwise extending slot in the frusto-conical end portion, said slot having a leading face and a trailing face as defined by direction of rotation of the shell cutter member;
a blade member on said trailing face of said slot and spaced from the leading face, said blade member having a cutting edge positioned beyond the frusto-conical end portion of said body member and being generally parallel to said frusto-conical end portion of said body member, said blade member having a chip receiving surface opposing the leading face of said slot and extending rearwardly from the cutting edge of the blade member and inwardly of the body member in a direction to cause chips removed from the pipe to be directed inwardly and upwardly into the chamber of said hollow body member above the coupon;
and,
means to retain the coupon cut from the pipe so that the coupon prevents chips from falling from said chamber of said body member into the hole cut, said coupon retaining means being a pilot drill extending below the lower end of said frusto-conical end portion.

2 more elements

In combination:

a large diameter plastic pipe having a wall thickness;
and
a rotatable shell cutter member for cutting a hole in said large diameter plastic pipe by cutting a coupon therein to form the hole and enlarging the formed hole when the shell cutter member is positively advanced against the pipe at a predetermined distance per rotation of the same, said shell cutter member including,
a metal hollow body member closed at one end and open at its other end to define a chamber for chips cut from said pipe, said body member having a cylindrical portion terminating at the said other end in a frusto-conical end portion,
a generally lengthwise extending slot in the frusto-conical end portion, said slot having a leading face and a trailing face as defined by direction of rotation of the shell cutter member,
a blade member on said trailing face of said slot and spaced from the leading face, said blade member having a cutting edge positioned beyond the frusto-conical end portion of said body member and being generally parallel to said frusto-conical end portion of said body member, said blade member having a chip receiving surface opposing the leading face of said slot and extending rearwardly from the cutting edge of the blade member and inwardly of the body member in a direction to cause chips removed from the pipe to be directed inwardly and upwardly into the chamber of said hollow body member above the coupon,
said body member having predetermined dimensions for an inside diameter of said cylindrical portion, an effective length of said chamber from an upper end of the frusto-conical end portion to the closed end of said body member and an outside diameter of said cylindrical portion, said predetermined dimensions being determined by the formula ##EQU3## Where:
AI = Cross-Sectional Inside Area of Body Member Along Length E E = Effective Length of Said Chamber
P.F.A. = Projected Frontal Area of Pipe (approximately equal to cross-sectional area of outside of body)
T = Thickness of Pipe
C = Constant for Packing Density of Chips;
and
means to retain the coupon cut from the pipe so that the coupon prevents chips from falling from said chamber of said body member into the hole cut.

10 more elements

Dependencies are inferred from the claim text.

Chipless shell cutter for large diameter plastic pipe

Life of this patent

Chipless shell cutter for large diameter plastic pipe

Life of this patent

Abstract

Claims23