Apparatus for making corrugated plastic pipes with integral coupler collar

Claim 2

Apparatus for continuously making plastic pipes, each having an elongate tubular corrugated body and an enlarged coupler collar provided with latching members on one end of the body, said apparatus comprising, an extruder for continuously extruding hot plastic naterial in the form of a tube. a series of cooperating pairs of forwardly moving die blocks defining a molding zone for receiving and molding the tube of hot plastic material, most of the pairs of die blocks being body-forming die blocks having an annularly corrugated concave inner surface defining at body-forming mold cavity, at least one of the cooperating pairs of die blocks being collar-forming die blocks having non-corrugated generally cylindrical inner surface portions defining a collar-forming mold cavity of greater diameter than said body-forming mold cavities, said pair of collar-forming die blocks also having a plurality of arcuately spaced, relatively small projections carried by and extending inwardly from said generally cylindrical inner surface portions for forming inwardly projecting latching members on each collar being molded, said projections defining areas of smaller internal diameter to aid in engaging the hot plastic material for stabilizing the same in the surrounding areas of said greater diameter cylindrical mold cavity to prevent migration of the hot plastic material, means for creating a pressure differential in said molding zone of a higher pressure inside the hot plastic tube as compared to the outside of the tube to expand the hot plastic tube against said mold cavities and thereby form a series of successive, closely spaced elongate corrugated tubular bodies with interconnected relatively short collars having integrally formed latching members, between the adjacent corrugated tubular bodies, and tube severing means spaced downstream of said molding zone for successively transversely severing the tube along the juncture between the end of the enlarged collar and the adjoining tubular corrugated body to thereby form a plurality of pipes, each having at one thereof a relatively short integral enlarged coupler collar having integrally formed latching members thereon.

Claim 3

Apparatus according to claim 1 wherein said plurality of arcuately spaced, relatively small projections carried by and extending inwardly from said generally cylindrical inner surface portions of said collar-forming die blocks comprise a set of projections on each of the die blocks.

Claim 4

Apparatus according to claim 1 wherein said plurality of arcuately spaced, relatively small projections carried by and extending inwardly from said generally cylindrical inner surface portions of said collar-forming die blocks comprise substantially equal spaced apart projections.

Claim 5

Apparatus according to claim 1 wherein said cooperating pairs of collar-forming die blocks also have annularly corrugated inner surface portions thereon.

Claim 6

Apparatus according to claim 1 further comprising mEans positioned downstream of said severing means for accumulating and stacking the severed pipe in stacked nesting relation preparatory to securing the stacked nested pipes into bundles.

Claim 7

Apparatus for continuously making plastic pipes, each having an elongate tubular corrugated body and an enlarged coupler collar provided with latching members on one end of the body said apparatus comprising, an extruder for continuously extruding hot plastic material in the form of a tube, a series of cooperating pairs of forwardly moving die blocks defining a molding zone for receiving and molding the tube of hot plastic material, most of the pairs of die blocks being body-forming die blocks having an annularly corrugated concave inner surface defining a body-forming mold cavity, several of the cooperating pairs of die blocks being collar-forming die blocks spaced apart from each other with a series of said body-forming die blocks therebetween, each of said collar-forming die blocks having non-corrugated generally cylindrical inner surface portions defining a collar-forming mold cavity of greater diameter than said body-forming mold cavities, said pairs of collar-forming die blocks also having a plurality of arcuately spaced, relatively small projections carried by and extending inwardly from said generally cylindrical inner surface portions for forming inwardly projecting latching members on each collar being molded, said projections defining areas of smaller internal diameter to aid in engaging the hot plastic material for stabililzing the same in the surrounding areas of said greater diameter cylindrical mold cavity to prevent migration of the hot plastic material. means for creating a pressure differential in said molding zone of a higher pressure inside the hot plastic tube as compared to the outside of the tube to expand the hot plastic tube against said mold cavities and thereby form a series of successive, closely spaced elongate corrugated tubular bodies with interconnected relatively short collars having integrally formed latching members, between the adjacent corrugated tubular bodies, and tube severing means spaced downstream of said molding zone for successively transversely severing the tube along the juncture between the end of the enlarged collar and the adjoining tubular corrugated body to thereby form a plurality of pipes, each having at one end thereof a relatively short integral enlarged coupler collar having integrally formed latching members thereon.

Claim 8

Apparatus for continuously making plastic pipes, each having an elongate tubular corrugated body and an enlarged coupler collar provided with latching members on one end of the body said apparatus comprising, an extruder for continuously extruding hot plastic material in the form of a tube, a series of cooperating pairs of forwardly moving die blocks defining a molding zone for receiving and molding the tube of hot plastic material, most of the pairs of die blocks being body-forming die blocks having an annularly corrugated concave inner surface defining a body-forming mold cavity, several of the cooperating pairs of die blocks being collar-forming die blocks spaced apart from each other with a series of said body-forming die blocks therebetween, each of said collar-forming die blocks having non-corrugated generally cylindrical inner surface portions defining a collar-forming mold cavity of greater diameter than said body-forming mold cavities, said pairs of collar-forming die blocks also having a plurality of arcuately spaced, relatively small projections carried by and extending inwardly from said generally cylindrical inner surface portions for forming inwardly projecting latching members on each collar being molded, said projections defining areas of smaller internal diameter to aid in engaging the hot plastic material for stabililzing the same in the surrounding areas of said greater diameter cylindrical mold cavity to prevent migration of the hot plastic material. means for creating a pressure differential in said molding zone of a higher pressure inside the hot plastic tube as compared to the outside of the tube to expand the hot plastic tube against said mold cavities and thereby form a series of successive, closely spaced elongate corrugated tubular bodies with interconnected relatively short collars having integrally formed latching members, between the adjacent corrugated tubular bodies, and tube severing means spaced downstream of said molding zone for successively transversely severing the tube along the juncture between the end of the enlarged collar and the adjoining tubular corrugated body to thereby form a plurality of pipes, each having at one end thereof a relatively short integral enlarged coupler collar having integrally formed latching members thereon.

Claim 9

Apparatus according to claim 6 wherein said plurality of arcuately spaced, relatively small projections carried by and extending inwardly from said generally cylindrical inner surface portions of said collar-forming die blocks comprise a set of projections on each of the die blocks.

Claim 10

Apparatus according to claim 6 wherein said plurality of arcuately spaced, relatively small projections carried by and extending inwardly from said generally cylindrical inner surface portions of said collar-forming die blocks comprise substantially equally spaced apart projections.

Claim 11

Apparatus according to claim 6 wherein said cooperating pairs of collar-forming die blocks also have annularly corrugated inner surface portions thereon.

Claim 12

Apparatus according to claim 6 further comprising means positioned downstream of said severing means for accumulating and stacking the severed pipe in stacked nesting relation preparatory to securing the stacked nested pipes into bundles.