US4982347A — Process and apparatus for producing temperature p…

Claim 1

Independent Claim 214 words

A manufacturing process in which a given target temperature profile T is established in a workpiece, said process including the steps of: providing a belt furnace with a plurality of spaced apart heaters in an elongated passageway and respective thermostats for the heaters; adjusting said belt furnace thermostats to respective temperature settings TS X which satisfy a first equation f(α,TS X , CF Y )≈T where α is a set of thermal parameters for the workpiece, f( ) is a function which approximates the temperature of said workpiece using said thermostat settings TS X and said workpiece thermal parameters α, and CF Y is a set of correction factors which compensate for errors in the approximation; passing said workpiece through said belt furnace with said heater thermostats at said setting TS X ; measuring an actual temperature profile A(TS X ) of said workpiece during said passing step; repeating said passing step on multiple workpieces if said measured actual temperature profile A(TS X ) matches said target temperature profile T within a predetermined tolerance; otherwise, determining a new set of correction factors CF Y which satisfies a second equation f(α,TS X , CF Y )=A(TS X ); and thereafter repeating the above steps with said new set of correction factors in said first equation.

Claim 2

Dependent Claim 214 words

A manufacturing process in which a given target temperature profile T is established in a workpiece, said process including the steps of: providing a belt furnace with a plurality of spaced apart heaters in an elongated passageway and respective thermostats for the heaters; adjusting said belt furnace thermostats to respective temperature settings TS X which satisfy a first equation f(α,TS X , CF Y )≈T where α is a set of thermal parameters for the workpiece, f( ) is a function which approximates the temperature of said workpiece using said thermostat settings TS X and said workpiece thermal parameters α, and CF Y is a set of correction factors which compensate for errors in the approximation; passing said workpiece through said belt furnace with said heater thermostats at said setting TS X ; measuring an actual temperature profile A(TS X ) of said workpiece during said passing step; repeating said passing step on multiple workpieces if said measured actual temperature profile A(TS X ) matches said target temperature profile T within a predetermined tolerance; otherwise, determining a new set of correction factors CF Y which satisfies a second equation f(α,TS X , CF Y )=A(TS X ); and thereafter repeating the above steps with said new set of correction factors in said first equation.

Claim 3

Dependent Claim 29 words

A process according to claim 1 wherein said function f( ) approximates temperature changes in said workpiece due to convection and ignores temperature changes due to conduction and radiation.

Claim 4

Dependent Claim 29 words

A process according to claim 1 wherein said function f( ) approximates temperature changes in said workpiece due to radiation and ignores temperature changes due to conduction and convection.

Claim 5

Dependent Claim 83 words

A process according to claim 1 wherein said function f( ) is of the form: ##EQU2## where T 0 is temperature of said workpiece at the start of a region in said passageway; T A is the air temperature in said region; A, V, ρ, C P respectively are the surface area, volume, density, and heat capacity of said workpiece; h(v) is a function if air velocity v in said region; and τ is the time that said workpiece spends in said region.

Claim 6

Dependent Claim 84 words

A process according to claim 1 wherein said function f( ) is of the form: ##EQU3## where T 0 is the temperature of said workpiece at the start of a region in said passageway; T A is the air temperature in said region; A, V ρ, CP P respectively are the surface area, volume, density, and heat capacity of said workpiece; h(v) is a function of air velocity v in said region; and τ is the time that said workpiece spends in said region.

Claim 7

Dependent Claim 84 words

A process according to claim 1 wherein said function f( ) is of the form: ##EQU4## where T 0 is the temperature of said workpiece at the start of a region in said passageway; T A is the air temperature in said region; A, V, ρ, C P respectively are the surface area, volume, density, and heat capacity of said workpiece; h(v) is a function of air velocity v in said region; and τ is the time that said workpiece spends in said region.

Claim 8

Dependent Claim 35 words

A process according to claim 1 wherein said function of f( ) is evaluated in a sequential fashion for a plurality of subregions along said passageway which ranges from five to fifteen per furnace heater.

Claim 9

Dependent Claim 154 words

A manufacturing system, for producing a target temperature profile T in a workpiece; said system comprising: a belt furnace which has a plurality of spaced apart heaters in an elongated passageway and respective thermostats for said heaters; and a controller for selecting a set of settings TS X for said thermostats; said controller including a means for approximating the temperature profile T which will occur in said workpiece as it passes through said furnace passageways by evaluating an equation f(α, TS X , CF Y )≈T where f( ) is a function of said thermostat settings TS x and a set of thermal parameters α for said workpiece and a set of correction factors CF Y ; and said controller further including a means for compensating for differences between the approximated temperature profile and the actual temperature profile that is produced when said workpiece is passed through said furnace, by modifying said correction factors.

Claim 10

Dependent Claim 154 words

A manufacturing system, for producing a target temperature profile T in a workpiece; said system comprising: a belt furnace which has a plurality of spaced apart heaters in an elongated passageway and respective thermostats for said heaters; and a controller for selecting a set of settings TS X for said thermostats; said controller including a means for approximating the temperature profile T which will occur in said workpiece as it passes through said furnace passageways by evaluating an equation f(α, TS X , CF Y )≈T where f( ) is a function of said thermostat settings TS x and a set of thermal parameters α for said workpiece and a set of correction factors CF Y ; and said controller further including a means for compensating for differences between the approximated temperature profile and the actual temperature profile that is produced when said workpiece is passed through said furnace, by modifying said correction factors.

Claim 11

Dependent Claim 29 words

A controller according to claim 8 wherein said function f( ) approximates temperature changes in said workpiece due to convection and ignores temperature changes due to conduction and radiation.

Claim 12

Dependent Claim 29 words

A controller according to claim 8 wherein said function f( ) approximates temperature changes in said workpiece due to radiation and ignores temperature changes due to conduction and convection.

Claim 13

Dependent Claim 84 words

A controller according to claim 8 wherein said function f( ) is of the form: ##EQU5## where T 0 is the temperature of said workpiece at the start of a region in said passageway; T A is the air temperature in said region; A, V, ρ, C P respectively are the surface area, volume, density, and heat capacity of said workpiece; h(v) is a function of air velocity v in said region; and τ is the time that said workpiece spends in said region.

Claim 14

Dependent Claim 84 words

A controller according to claim 8 wherein said function f( ) is of the form ##EQU6## where T 0 is the temperature of said workpiece at the start of a region in said passageway; T A is the air temperature in said region; A, V, ρ, C P respectively are the surface area, volume, density, and heat capacity of said workpiece; h(v) is a function of air velocity v in said region; and τ is the time that said workpiece spends in said region.

Claim 15

Dependent Claim 84 words

A controller according to claim 8 wherein said function f( ) is of the form: ##EQU7## where T 0 is the temperature of said workpiece at the start of a region in said passageway; T A is the air temperature in said region; A, V, ρ, C P respectively are the surface area, volume, density, and heat capacity of said workpiece; h(v) is a function of air velocity v in said region; said τ is the time that said workpiece spends in said region.

Claim 16

Dependent Claim 34 words

A controller according to claim 8 wherein said function f( ) is evaluated in a sequential fashion for a plurality of subregions along said passageway which ranges from five to fifteen per furnace heater.

Claim 17

Dependent Claim 22 words

A controller according to claim 8 wherein said means for approximating and said means for compensating are comprised of digital logic circuits.

Claim 18

Dependent Claim 27 words

A controller according to claim 8 wherein said means for approximating and said means for compensating are comprised of computer programs in a general purpose digital computer.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1993-12-31	1994-07-02	1995-01-01	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1997-12-31	1998-07-02	1999-01-01	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2001-12-31	2002-07-02	2003-01-01	$7700.00	Window Closed / Lapsed

Process and apparatus for producing temperature profiles in a workpiece as it passes through a belt furnace

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