Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
  • B29C51/26—Component parts, details or accessories; Auxiliary operations
  • B29C51/42—Heating or cooling
  • B29C51/421—Heating or cooling of preforms, specially adapted for thermoforming
  • B29C51/422—Heating or cooling of preforms, specially adapted for thermoforming to produce a temperature differential
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
  • B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
  • B29C35/0288—Controlling heating or curing of polymers during moulding, e.g. by measuring temperatures or properties of the polymer and regulating the process
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
  • B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
  • B29C35/08—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
  • B29C49/42—Component parts, details or accessories; Auxiliary operations
  • B29C49/64—Heating or cooling preforms, parisons or blown articles
  • B29C49/6409—Thermal conditioning of preforms
  • B29C49/6418—Heating of preforms
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
  • B29C49/42—Component parts, details or accessories; Auxiliary operations
  • B29C49/64—Heating or cooling preforms, parisons or blown articles
  • B29C49/6409—Thermal conditioning of preforms
  • B29C49/6436—Thermal conditioning of preforms characterised by temperature differential
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B3/00—Ohmic-resistance heating
  • H05B3/0033—Heating devices using lamps
  • H05B3/0038—Heating devices using lamps for industrial applications
  • H05B3/0057—Heating devices using lamps for industrial applications for plastic handling and treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
  • B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
  • B29C35/08—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation
  • B29C35/0805—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation using electromagnetic radiation
  • B29C2035/0822—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation using electromagnetic radiation using IR radiation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
  • B29C49/42—Component parts, details or accessories; Auxiliary operations
  • B29C49/78—Measuring, controlling or regulating

Definitions

• the invention relates to a method and a device for thermoforming thermoplastics according to the preamble of claim 1 and the preamble of claim 12.
• the blank has a temperature profile suitable for deformation, which is adapted to the end product to be produced.
• a temperature profile can be relatively complicated or very inhomogeneous over the circumferential surface of the molded body.
• an almost constant temperature over the entire wall thickness, ie the "depth" of the blank is desired.
• hot air sources or infrared radiators in many cases also using heated molds working in several stages (e.g. in deep drawing) have been used up to now.
• the heat can be supplied practically exclusively via the surface of the blank, so that in order to achieve the constant temperature inside the material, that is to say via its wall thickness, it is dependent on the heat transport by heat conduction within the material. This in turn presupposes a relatively slow warming up or dwell times within which the temperature compensation (over the depth of the material) can take place.
• the method and device of the type mentioned in the introduction are complex and prone to failure.
• the setting of a suitable temperature profile over the spatial dimensions of the blank is extremely difficult.
• the invention has for its object to develop methods and apparatus of the type mentioned in such a way that simplified heating of the blank can be achieved with improved temperature accuracy.
• An essential point of the invention is that the heat is supplied to the blank via radiation of a defined intensity of a radiation source in such a way that the energy is absorbed not only on the outer surfaces of the blank but also simultaneously inside the material for increasing the temperature. This in turn occurs because the intensity maximum of the radiation source is adapted to the absorption or transmission properties of the thermoplastic to be processed in such a way that the energy can actually penetrate into the material and not - as with the otherwise longer wavelengths - already in near-surface areas of the blank is absorbed.
• the intensity maximum is preferably in the near infrared, in particular 0.8-1.4 ⁇ m, preferably 0.8-1.0 ⁇ m, ie in a range of wavelengths that are considerably shorter than the wavelengths at which the intensity maximum is more common Sources of heat radiation. It is preferred not only to achieve a considerably more uniform heating of the blank in its depth, but also a significantly faster heating. When using a temperature radiator with at least essentially a continuous radiation spectrum, this results from the fact that with the setting of the intensity maximum to shorter wavelengths proposed here, the radiation intensity increases approximately with the 4th power of the temperature of the radiator.
• the radiation is preferably distributed to the blank by means of optical devices, in particular mirrors, gratings or similar devices of the radiation optics, such that a temperature profile adapted to the shaping device is set within the blank after the defined period of time has elapsed. So it is not the radiation source z. B. adjusted or changed by the supply of energy, rather the radiation supplied to the blank is "adjusted” according to the requirements. It is advantageous here that the radiation has its maximum intensity at the aforementioned wavelength ranges, so that the usual means of radiation optics can be used.
• the objects or blanks to be heated are particularly preferably subjected to a radiation flux density of more than 0.5 MW / m 2 , in particular more than 1 MW / m 2 .
• the wavelength of the intensity maximum is preferably determined by adjustment, but in particular by regulation (ie
• Measurement and feedback of the relevant radiation quantities) of the temperature of a heating element The setting of the filament temperature of a halogen lamp is particularly preferred. Since this has to be set to relatively high temperatures (which are unusually high for halogen lamps (in order to achieve the short wavelengths mentioned)), appropriate measures are preferably taken to nevertheless ensure a long service life of the halogen lamp used. In particular, special cooling measures are taken both in the area of the (quartz) glass bodies and in the area of the base of the halogen lamps.
• the distance between the radiation source and the blank and / or an optical filter device such as grating or gray filter or the like and / or chopper devices is preferably used alternatively or cumulatively.
• the procedure is preferably such that the defined heating or irradiation period does not significantly exceed 10 seconds, particularly preferably 5 seconds. This ensures, on the one hand, that the usual blanks or preforms are evenly heated, and on the other hand, production can be carried out at high speed.
• the preform is preferably handed over to the molding tool, in particular a blow-stretching device, for deformation essentially immediately after exposure to the radiation without a substantial dwell time free of radiation exposure. This ensures that the temperature profile set (in particular by optics) along the body cannot change due to heat conduction within the preform.
• the blank is deformed from the tool onto the blank in an essentially cold tool without substantial heat input.
• this can be done by molding the blank in a single drawing operation. This ensures that the temperature profile set (in particular by optical means) in the blank is essentially maintained and the risk of the blank sticking to the deep-drawing tool is avoided, as is the case in particular with those deep-drawing tools in which the heating of the blank is done by the tool itself.
• the device according to the invention thus comprises a radiation source with a regulating device for regulating an emission wavelength range of the radiation source in such a way that the intensity maximum of the radiation source lies in a wavelength range within which the thermoplastic has a low degree of absorption or a higher degree of transmission than incident or incident light at longer wavelengths Radiation absorbs or lets through or lets in.
• This radiation source is preferably designed so that its in- intensity maximum in the near infrared, in particular 0.8 to 1.4 and particularly preferably 0.8 to 1.0 ⁇ m.
• the degree of absorption should be so low or the degree of transmission so high that a penetration depth of the radiation corresponding to the thickness of the blank to be processed is ensured and the blank is not only on its surface but from the beginning (i.e. without temperature compensation via heat conduction) is heated inside.
• Mirrors, gratings or similar devices of the radiation optics are preferably provided in order to heat the blank with a temperature profile which is optimal for shaping.
• a current controller is preferably provided for regulating the filament temperature, which current value is obtained from a correspondingly designed sensor (pyrometer) in order to determine the filament temperature or the wavelength range, at which the intensity maximum of the radiation source is to be kept constant and adjusted according to the specifications mentioned at the beginning.
• the intensity is controlled (by applying disturbance variables or by comparing target and actual values) so that the desired temperature profile is reached within the set time of exposure to radiation.
• This intensity setting can be done by the distance between the radiation source and the blank and / or optical filter devices and / or a chopper device, which so to speak "radiation packets" get to the blank, the chopper speed being chosen so that the "packet durations" are very short in relation to the Total period over which energy is supplied to the blank.
• the arrangement is selected in such a way that the blank can be produced within a period of less than 10 sec, preferably from less than 5 sec in the area of the radiation source and removed from it again, so that no substantial temperature compensation can occur while changing the temperature profile (set by optical devices).
• the entire device for the production of PET bottles is designed and equipped with stations located close to one another (radiation source, molding tool) and with fast conveying devices, so that there is no significant dwell time of the blank or preform within which radiation energy is applied can be done for heating before deformation in the blow-stretching device. This also keeps the set temperature profile in the preform.
• a deep-drawing tool In the production of deep-drawn parts, a deep-drawing tool is used which has a relatively low temperature (measured in relation to the deep-drawing tools previously used), preferably only a single deep-drawing tool being provided, and the blank being thus formed in a single deep-drawing process.
• the advantage here is that there is no significant change in the temperature profile previously set by the corresponding radiation energy supply.

Landscapes

• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Health & Medical Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Manufacturing & Machinery (AREA)
• Toxicology (AREA)
• Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)
• Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=7839769

Family Applications (1)

Country Status (8)

Families Citing this family (20)

Family Cites Families (9)

• 1997
  • 1997-08-21 DE DE1997136462 patent/DE19736462C2/de not_active Expired - Lifetime
• 1998
  • 1998-08-19 WO PCT/EP1998/005266 patent/WO1999010160A1/de not_active Application Discontinuation
  • 1998-08-19 EP EP98947440A patent/EP1005412A1/de not_active Withdrawn
  • 1998-08-19 AU AU94359/98A patent/AU9435998A/en not_active Abandoned
  • 1998-08-19 BR BR9811610-0A patent/BR9811610A/pt not_active IP Right Cessation
  • 1998-08-19 JP JP2000507520A patent/JP4562284B2/ja not_active Expired - Lifetime
  • 1998-08-19 CN CN 98808333 patent/CN1267253A/zh active Pending
  • 1998-08-19 CA CA002301053A patent/CA2301053A1/en not_active Abandoned

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events