Oven for heating continuous tubing

Claim 2

An oven comprising: first and second chambers, at least two conduits located between and opening into said chambers, means for delivering air at a desired temperature to said first chamber and circulating said air through each of said conduits in a direction from said first chamber to said second chamber and out of said second chamber back to said first chamber, a plurality of stationary spaced guide members in each of said conduits, at least one wheel rotatably mounted in said second chamber, a plurality of spaced guide members fixedly secured to the outer periphery of said wheel, said wheel being so located that the guide members thereon are in substantially the same plane as a plane passing through the guide members in said conduits.

Claim 3

The structure as recited in claim 1, wherein said guide members are polytetrafluoroethylene.

Claim 4

The structure as recited in claim 1 further comprising: a steam chamber surrounding each of said conduits, and means for communicating sTeam under pressure to said steam chambers.

Claim 5

The structure as recited in claim 1, wherein said means for delivering air to said exit chamber includes heating means, said heating means including a steam chamber, and means for communicating steam under pressure to said steam chamber.

Claim 6

The structure as recited in claim 1 further comprising: a steam chamber surrounding each of said conduits, means for communicating steam at a constant pressure to said conduit steam chambers, said means for delivering air to first exit chamber including heating means comprising a steam chamber, and means for communicating steam to said last named steam chamber at a varying pressure in response to the temperature of the air in said first chamber.

Claim 7

The structure as recited in claim 3, wherein said means for delivering air to said first chamber includes heating means, said heating means including a steam chamber, and means for communicating steam under pressure to said last named steam chamber.

Claim 8

An oven comprising: first and second chambers, at least first, second, and third conduits located between and opening into said chambers, means for delivering air at a desired temperature to said first chamber and circulating said air through each of said conduits in a direction from said first chamber to said second chamber and out of said second chamber back to said first chamber, a plurality of stationary spaced guide members in each of said conduits, at least one wheel rotatably mounted in said first chamber and at least one wheel rotatably mounted in said second chamber, a plurality of spaced guide members fixedly secured to the outer periphery of each of said wheels, said wheel in said second chamber being so located that the guide members thereon are in substantially the same plane as a plane passing through the guide members in said second and third conduits, said wheel in said first chamber being so located that the guide members thereon are in substantially the same plane as a plane passing through the guide members in said first and second conduits.

Claim 9

An oven comprising: first and second chambers, at least first, second, and third conduits located between and opening into said chambers, means for delivering air at a desired temperature to said first chamber and circulating said air through each of said conduits in a direction from said first chamber to said second chamber and out of said second chamber back to said first chamber, a plurality of stationary spaced guide members in each of said conduits, at least one wheel rotatably mounted in said first chamber and at least one wheel rotatably mounted in said second chamber, a plurality of spaced guide members fixedly secured to the outer periphery of each of said wheels, said wheel in said second chamber being so located that the guide members thereon are in substantially the same plane as a plane passing through the guide members in said second and third conduits, said wheel in said first chamber being so located that the guide members thereon are in substantially the same plane as a plane passing through the guide members in said first and second conduits.

Claim 10

The structure as recited in claim 7, wherein the planes of each wheel are at an angle to each other.

Claim 11

The structure as recited in claim 8, wherein said guide members are polytetrafluoroethylene.

Claim 12

The structure as recited in claim 9, wherein said guide members are generally U-shaped.

Claim 13

The structure as recited in claim 7 further comprising: a steam chamber surrounding each of said conduits, means for communicating steam at a constant pressure to said conduit steam chambers, said means for delivering air to said first chamber including heating means comprising a steam chamber, and means for communicating steam to said last named steam chamber at a varying pressure in response to the temperature of the air in said first chamber.

Claim 14

A process for heating a continuous thermoplastic tubing comprising: providing a multiple pass oven comprising a first chamber, a second chamber, a plurality of conduits in communication with and connecting said chambers; supplying heat to said conduits; supplying heated air to said first chamber; circulating said heated air from said first chamber through said conduits to said second chamber; exposing the entire outer surface of the tubing to the heated air by passing the tubing into one of said chambers and then through at least a first and second one of said plurality of conduits prior to discharging the same from said first chamber out of the oven; said tubing being passed through the first conduit by sliding the same over a plurality of fixed axially spaced guide members while turbulent hot air is being circulated through the first conduit; the tubing emerging from the first conduit into the other of said chambers and being wrapped around a plurality of circumferentially spaced guide members secured to a rotatable chamber wheel located in said other chamber and then passing through the second conduit in a direction toward said one chamber by sliding the same over a plurality of fixed aXially spaced guide members while turbulent hot air is being circulated through the second conduit.

Claim 15

A process for heating a continuous thermoplastic tubing comprising: providing a multiple pass oven comprising a first chamber, a second chamber, a plurality of conduits in communication with and connecting said chambers; supplying heat to said conduits; supplying heated air to said first chamber; circulating said heated air from said first chamber through said conduits to said second chamber; exposing the entire outer surface of the tubing to the heated air by passing the tubing into one of said chambers and then through at least a first and second one of said plurality of conduits prior to discharging the same from said first chamber out of the oven; said tubing being passed through the first conduit by sliding the same over a plurality of fixed axially spaced guide members while turbulent hot air is being circulated through the first conduit; the tubing emerging from the first conduit into the other of said chambers and being wrapped around a plurality of circumferentially spaced guide members secured to a rotatable chamber wheel located in said other chamber and then passing through the second conduit in a direction toward said one chamber by sliding the same over a plurality of fixed aXially spaced guide members while turbulent hot air is being circulated through the second conduit.

Claim 16

A process s defined in claim 12, wherein said tubing is of a crystalline mono- Alpha -olefin polymer and the heated air supplied to the exit chamber is slightly below the crystalline melting point of said tubing.

Claim 17

A process as defined in claim 13, wherein said mono- Alpha -olefin polymer is polypropylene.

Claim 18

A process for heating the entire outer surface of a continuous thermoplastic tubing comprising: providing a multiple pass oven comprising a first chamber, a second chamber, a plurality of conduits in communication with and connecting said chambers and at least one rotatable wheel in each of said chambers; supplying heat to said conduits; supplying heated air to said first chamber; circulating said heated air from said first chamber through said conduits to said second chamber; exposing the entire outer surface of the tubing to the heated air by passing the tubing into one of said chambers and then through at least a first and second one of said plurality of conduits prior to passing the same through a last conduit from the second chamber to the first chamber and out of the oven; said tubing being passed through the first conduit in a direction toward the exit chamber by sliding the same over a plurality of fixed axially spaced guide members while turbulent hot air is being circulated through the first conduit; the tubing emerging from the first conduit and being wrapped around a plurality of circumferentially spaced guide members secured to said wheel in the other of said chambers and then passing through the second conduit in a direction toward said one chamber by sliding the same over a plurality of fixed axially spaced guide members while turbulent hot air is being circulated through the second conduit; the tubing emerging from the second conduit and being wrapped around a plurality of circumferentially spaced guide members secured to said wheel in said one chamber; said tubing passing through the final conduit from said second chamber in a direction toward said first chamber by sliding the same over a plurality of fixed axially spaced guide members while turbulent hot air is being circulated through the final conduit in the opposite direction; the tubing emerging from the final conduit into said first chamber and then passing through the tubing through said first chamber and discharging the tubing from the oven.

Claim 19

A process for heating the entire outer surface of a continuous thermoplastic tubing comprising: providing a multiple pass oven comprising a first chamber, a second chamber, a plurality of conduits in communication with and connecting said chambers and at least one rotatable wheel in each of said chambers; supplying heat to said conduits; supplying heated air to said first chamber; circulating said heated air from said first chamber through said conduits to said second chamber; exposing the entire outer surface of the tubing to the heated air by passing the tubing into one of said chambers and then through at least a first and second one of said plurality of conduits prior to passing the same through a last conduit from the second chamber to the first chamber and out of the oven; said tubing being passed through the first conduit in a direction toward the exit chamber by sliding the same over a plurality of fixed axially spaced guide members while turbulent hot air is being circulated through the first conduit; the tubing emerging from the first conduit and being wrapped around a plurality of circumferentially spaced guide members secured to said wheel in the other of said chambers and then passing through the second conduit in a direction toward said one chamber by sliding the same over a plurality of fixed axially spaced guide members while turbulent hot air is being circulated through the second conduit; the tubing emerging from the second conduit and being wrapped around a plurality of circumferentially spaced guide members secured to said wheel in said one chamber; said tubing passing through the final conduit from said second chamber in a direction toward said first chamber by sliding the same over a plurality of fixed axially spaced guide members while turbulent hot air is being circulated through the final conduit in the opposite direction; the tubing emerging from the final conduit into said first chamber and then passing through the tubing through said first chamber and discharging the tubing from the oven.

Claim 20

A process as defined in claim 15, wherein said tubing is of a crystalline mono- Alpha -olefin polymer and the heated air supplied to the exit chamber is slightly below the crystalline melting point of said tubing.

Claim 21

A process as defined in claim 16, wherein said mono- Alpha -olefin polymer is polypropylene.