Apparatus for the manufacture of hollow frangible pipes

Claim 2

In an apparatus for the manufacture of hollow pipes comprising a hollow mold, a shaft disposed in said mold and extending axially thereof, a packer head mounted adjacent one end of said shaft and movable therewith, and means for imparting longitudinal and rotary movement to said shaft to move the packer head through said mold whilst continuously rotating same, the improvement which comprises a mechanism for automatically and continuously varying the rate of feed of material supplied to the apparatus and the packing density of the material being packed against the inner surface of the mold, said Mechanism adapted to maintain a preselected relationship between the rate of feed of said material to the mold and the rate of longitudinal movement of the shaft and associated packer head through the mold whereby the pipe is uniformly and densely packed throughout its length.

Claim 3

Apparatus as claimed in claim 1 wherein the material feed is controlled by a fluid motor supplied from a first fluid source through a first variable flow valve, the axial movement of said packer head being effected by fluid operated cylinders supplied from the or a second fluid source through a second variable flow valve, said first and second variable flow valves being mechanically interlinked whereby movement of one of said valves in one direction between its opened and closed position produces a movement of the other valve in the opposite direction between its open and closed position, the relative movement of said first and second valves being adjusted to maintain a predetermined relationship between the rates of feed of material to the mold and the rate of axial movement of the packer head through the mold.

Claim 4

Apparatus as claimed in claim 1 wherein the rate of axial movement of said packer head through said mold is continuously varied in dependence on the resistance to the rotary motion of the packer head and is maintained in a predetermined relationship with the rate of feed of material to the mold.

Claim 5

Apparatus as claimed in claim 1 wherein an increase in the density of packing of the material in the mold by the packer head produces a decrease in the rate of feed of material to the mold and a predetermined proportional increase in the rate of axial movement of the packer head through the mold.

Claim 6

Apparatus as claimed in claim 1 wherein the material feed is controlled by a fluid motor supplied from a first fluid source to a first variable flow valve, the axial movement of said packer head being effected by fluid operated cylinders supplied from a second fluid source through a second variable valve, including a bar, and first and second cams mounted in spaced relationship on said bar, said first and second cams associated with and adapted upon movement of said bar to actuate said first and second control valves respectively, said packer head adapted to impart linear motion to said bar through a fluid actuated cylinder, movement of said cylinder being proportional to the resistance offered to the rotary motion of the packer head by the material being packed against the inner surface of the mold and adapted to actuate said first and second valves simultaneously in mutually opposite directions.

Claim 7

Apparatus as claimed in claim 1 wherein the molding material is concrete.