US3684258A - Apparatus and method for billet heating and solid stretch forming - Google Patents

Apparatus and method for billet heating and solid stretch forming Download PDF

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Publication number
US3684258A
US3684258A US79163A US3684258DA US3684258A US 3684258 A US3684258 A US 3684258A US 79163 A US79163 A US 79163A US 3684258D A US3684258D A US 3684258DA US 3684258 A US3684258 A US 3684258A
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Prior art keywords
billets
heating
plates
heating plates
set forth
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US79163A
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Paul M Coffman
Herbert G Johnson
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B13/00—Conditioning or physical treatment of the material to be shaped
    • B29B13/02—Conditioning or physical treatment of the material to be shaped by heating

Definitions

  • ABSTRACT This application discloses heating apparatus and method of heating employing longitudinally extending heating plates which maintain contact proximity with both surfaces of a line of billets at all times, i.e., actual surface contact with both sides of the billets or full surface contact with the lower side and close proximity at the upper side for engaging projecting portions if warped or burred, the plates being provided with a coating of a material having a low coefficient of friction, such as a fluorocarbon polymer, and means for advancing the line of billets along between the heating plates while the space between plates is maintained constant.
  • a material having a low coefficient of friction such as a fluorocarbon polymer
  • the invention is particularly applicable for heating plastic polymer materials which are cold-workable" and work-strengthenable in the solid state, that is between an upper temperature near a so-called melting point at which the material begins to change shape without any applied force except gravity and atmospheric pressure, say up to l-25 p.s.i., and a lower temperature, referred to as the glass-transition" point, at which the material becomes brittle and strongly resists flow by applied force unless very great and maintained for a relatively long time.
  • plastic polymer materials polyethylene, polypropylene, and a number of others which are known and need not be named, have very low thermal conductivity so that it is difficult to drive heat into the interior of even relatively thin sections sufiiciently to provide the desired substantially uniform temperature throughout the plastic body.
  • the heating temperature must not be above the melting point or the outer surface will be melted before the center has been heated sufficiently.
  • billets are moved along continuously between heating plates which are maintained in a fixed space relationship of contact proximity, either in contact with both faces of the billets or in full contact with one face and so near the other face as to engage any warped or burred surfaces of the billets, the plates being coated with a surfacing material having a low coefiicient of friction with the billets.
  • the preferred coating material is a fluorocarbon polymer, specifically polytetrafluoroethylene being used at present.
  • the maximum temperature short of the melting point can be maintained to heat the billets to within 5 to 20 F. below the melting point and to heat the interior portion of the billets to within about 3 F. of the surface temperature.
  • FIG. 1 is a side elevation, partly in section, of billet heating apparatus embodying the invention
  • FIG. 2 is a top plan view, some parts being omitted;
  • FIG. 3 is an enlarged view in the zone 3 shown in section in FIG. 1;
  • FIG. 4 is an enlarged local section showing support means for the heating plates.
  • the apparatus illustrated herein comprises a main frame 10 which is shown as being mounted on caster wheels 11 for portability.
  • a lower heating plate unit 12 is mounted on the main frame 10 and an upper heating plate unit 13 is carried (FIG. 4) by springs 14 adjustable by nuts on threaded rods 15 carried by suitable frame supports 16.
  • Each heating unit l2, 13 comprises an inner billetengaging metal plate l7 of good thermal conductivity, as of aluminum, copper, or steel, heating means indicated by fluid tubes 18 (suitable fluid heating and control means being assumed) and outer cover means 19 which may be a metal plate or insulation or both.
  • the plates are provided on the billet-contacting sides with a coating material of low friction coefficient, such as a fluorocarbon polymer, preferably polytetrafluoroethylene, to ease the travel of billets between the plates under the pressure maintained on them.
  • Means are provided for feeding billets and moving them along between the heating plate units.
  • the term billets is meant to include sheets from which billets are cut but preferably, and as here shown, the billets are assumed to have been pre-cut in the cold state before being supplied to the heating apparatus.
  • the billet advancing means herein shown comprises transverse conveyor bars 20, which are thinner than the thinnest billets to be heated, secured to endless conveyor belt or chain means 21 carried over end pulleys or sprockets 22.
  • the pulleys for one end are shown to be adjustable for tightening the belts, as by slides 23 and adjusting screws 24.
  • Billets W are fed in between adjacent pusher bars 20, as from billet stack holding means or hopper 25 mounted above the infeed end of the lower heating plate unit 12, the upper heating plate unit 13 being cut out or shortened to allow the billets to feed down upon the lower plate heating unit.
  • a shaft 27 carrying the feed conveyor pulleys 22 at the feed-out or delivery end is driven by a belt or sprocket chain 28 from a gear box unit 29 driven by a motor M, the chain passing over suitable sprockets.
  • the gear unit 29 is shown to be mounted on a slide 30 adjustable by a screw 31 to control tension in the belt or chain 28.
  • a control unit 32 is provided for regulating the speed of the motor drive.
  • the drive shaft 33 of the gear unit may be provided with a magnetic clutch-brake unit 34 for starting and stopping the feed of billets when desired.
  • the control unit 32 also assists in regulating the means for transferring heated billets from the heating means to associated forming means and controlling the action of the forming means.
  • Heated billets are delivered to a chute 52 from which they drop upon a table 53 and from this they are fed, as by a power pusher 50 operated by a power device 51 (fluid cylinder-piston) 54 of a die-mold unit 55 of a forming press 56 having a clamping plunger 57 and a forming plunger 58 cooperating with a bottom plunger 59
  • the forming press 56 and transfer pusher 50 have a faster operating cycle than the heater delivery to allow ample time for the press to form and discharge an article before another billet blank can be fed out.
  • the chute and transfer table may be enclosed to minimize contact with air but in any case the exposure with air would be very brief.
  • the conveyor bars feed out a billet each time a bar moves beneath the stack of billets and pushes it forward between the heating plates against such pressure as is adjustably maintained between them.
  • the lower front edge of the upper heating plate is beveled to assist the entry of billets between the plates.
  • the coating of low-friction material on the heating plates eases the travel of the billets between the plates. It is so thin that it does not substantially reduce the heat transfer although its own heat conductivity is not high.
  • the billets are so closely confined between the heating plates throughout their whole travel between them, since the heating plates are maintained in contact proximity with the billets at all times and never separated, that the exposure of heating billets to air is minimized.
  • the unit 60 is illustrated as bein of the type responsive to heat, having a ocation M m a cut-out opening in the table if needed; but if a weight-sensitive indicator is used the table will be supported, as on light springs, to make it responsive to the weight of a billet falling upon it.
  • a trip-responsive device activated by the passage of a billet to the table might also be used.
  • Apparatus for heating billets of plastic polymer material having a low coefficient of heat transfer and having a high coefficient of adhesion and friction at the melting point comprising in combination, spaced longitudinally extending heating plates arranged one above the other to receive a line of billets in surface contact with at least the lower one of said plates and in very close proximity with at least possible contact with the upper plate, said plates having a coating of material having a low coefficient of friction with the billets, and pushing means, traveling between said heating plates, for insertion between successive billets for advancing the line of billets between said plates while their position is maintained.
  • the method of heating flat polypropylene billets to within l F. of a predetermined surface temperature and an interior temperature within about 3 F. of the surface temperature which comprises disposing a line of polypropylene billets between longitudinally extending heating plates, having a coating of material having a low coefficient of friction with the billets, maintaining said heating plates in contact proximity engagement with the billets continuously, and moving the line of billets along between said heating plasts while contac proximity is maintained, the transit time being controlled to achieve the predetermined surface temperature of the billets as they reached the end of the heating plates.

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  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Forging (AREA)
  • Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
  • Press Drives And Press Lines (AREA)
  • Casting Or Compression Moulding Of Plastics Or The Like (AREA)
US79163A 1970-10-08 1970-10-08 Apparatus and method for billet heating and solid stretch forming Expired - Lifetime US3684258A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US7916370A 1970-10-08 1970-10-08

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US3684258A true US3684258A (en) 1972-08-15

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US79163A Expired - Lifetime US3684258A (en) 1970-10-08 1970-10-08 Apparatus and method for billet heating and solid stretch forming

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US (1) US3684258A (enrdf_load_html_response)
AU (1) AU460822B2 (enrdf_load_html_response)
BE (1) BE773399A (enrdf_load_html_response)
CA (1) CA968107A (enrdf_load_html_response)
DE (1) DE2149925A1 (enrdf_load_html_response)
FR (1) FR2110288B1 (enrdf_load_html_response)
GB (1) GB1359333A (enrdf_load_html_response)
IT (1) IT939950B (enrdf_load_html_response)
NL (1) NL7113633A (enrdf_load_html_response)
ZA (2) ZA716694B (enrdf_load_html_response)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4431404A (en) * 1982-08-26 1984-02-14 Whirlpool Corporation Method and apparatus for heating plastic sheet material
US4836764A (en) * 1987-10-13 1989-06-06 Questech Ventures Inc. Melt-phase thermal pressure apparatus for forming of plastic blanks into retortable containers
US4997691A (en) * 1987-10-13 1991-03-05 Questech Ventures, Inc. Retortable container
US5091231A (en) * 1988-10-13 1992-02-25 Questech Ventures, Inc. Retortable container
US20010028124A1 (en) * 1999-05-05 2001-10-11 Maytag Corporation Method for creating a substantially uniform temperature across a plastic sheet for delivery to an appliance liner thermoforming device
US20040043348A1 (en) * 2002-08-29 2004-03-04 Austin's Pizza Oven conveyor and method thereof
US20110074057A1 (en) * 2009-09-30 2011-03-31 Printpack Illinois, Inc. Methods and Systems for Thermoforming with Billets

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2919456A1 (de) * 1979-05-15 1980-12-04 Kannegiesser H Gmbh Co Vorrichtung zur verformung von aus kunststoffen geschaeumten platten
DE3942891A1 (de) * 1989-12-23 1991-06-27 Bayer Ag Verfahren zum thermoplastischen verformen von kunststoffen
CN112753788B (zh) * 2021-01-15 2022-11-22 湖北小稀藤茶叶有限公司 一种带有自动翻转的茶叶烘烤机

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2892263A (en) * 1955-06-15 1959-06-30 Beloit Iron Works Paper machine dryer
US3491989A (en) * 1968-07-03 1970-01-27 Weyerhaeuser Co Apparatus for heating moving sheet materials
US3502310A (en) * 1968-05-17 1970-03-24 Shell Oil Co Hot plate billet heater and method of heating

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2892263A (en) * 1955-06-15 1959-06-30 Beloit Iron Works Paper machine dryer
US3502310A (en) * 1968-05-17 1970-03-24 Shell Oil Co Hot plate billet heater and method of heating
US3491989A (en) * 1968-07-03 1970-01-27 Weyerhaeuser Co Apparatus for heating moving sheet materials

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4431404A (en) * 1982-08-26 1984-02-14 Whirlpool Corporation Method and apparatus for heating plastic sheet material
US4836764A (en) * 1987-10-13 1989-06-06 Questech Ventures Inc. Melt-phase thermal pressure apparatus for forming of plastic blanks into retortable containers
US4997691A (en) * 1987-10-13 1991-03-05 Questech Ventures, Inc. Retortable container
US5091231A (en) * 1988-10-13 1992-02-25 Questech Ventures, Inc. Retortable container
US20010028124A1 (en) * 1999-05-05 2001-10-11 Maytag Corporation Method for creating a substantially uniform temperature across a plastic sheet for delivery to an appliance liner thermoforming device
US6443721B1 (en) 1999-05-05 2002-09-03 Maytag Corporation Apparatus for creating a substantially uniform temperature across a plastic sheet for delivery to an appliance liner thermoforming device
US7101500B2 (en) 1999-05-05 2006-09-05 Maytag Corporation Method for creating a substantially uniform temperature across a plastic sheet for delivery to an appliance liner thermoforming device
US20040043348A1 (en) * 2002-08-29 2004-03-04 Austin's Pizza Oven conveyor and method thereof
US6776612B2 (en) * 2002-08-29 2004-08-17 Austin's Pizza Oven conveyor and method thereof
US20110074057A1 (en) * 2009-09-30 2011-03-31 Printpack Illinois, Inc. Methods and Systems for Thermoforming with Billets
US8287270B2 (en) 2009-09-30 2012-10-16 Printpack Illinois Inc. Methods and systems for thermoforming with billets
US8753106B2 (en) 2009-09-30 2014-06-17 Printpack Illinois, Inc. Billet carrier assembly

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Publication number Publication date
FR2110288A1 (enrdf_load_html_response) 1972-06-02
NL7113633A (enrdf_load_html_response) 1972-04-11
GB1359333A (en) 1974-07-10
IT939950B (it) 1973-02-10
BE773399A (nl) 1972-04-04
ZA716694B (en) 1972-06-28
AU460822B2 (en) 1975-05-08
CA968107A (en) 1975-05-27
AU3428471A (en) 1973-04-12
ZA716728B (en) 1972-06-28
FR2110288B1 (enrdf_load_html_response) 1974-08-19
DE2149925A1 (de) 1972-04-13

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