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| Nursing bottle with integral temperature sensor |
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| Multilayered container |
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| Plastic bottle forming machine |
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| Parison control in longitudinal stretch |
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| Bottle having ribbed bottom |
| OF THE PREFERRED EMBODIMENTS As shown on the drawings, and specifically in FIG. 1, a blow molding ... |
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| Method for thermal conditioning a thermoplastic parison |
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| Method for producing polyester containers |
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Method and apparatus for manufacturing of a container
| Details |
Inventors: Nilsson, Torsten;
Assignee: PLM AB (Malmo, SE)
Primary Examiner: Timm; Catherine
Assistant Examiner:
Attorney, Agent or Firm: Keck, Mahin & Cate
A method and an apparatus to thermocrystallize amorphous thermoplastic material in a bottom portion (11) of a preform (10) while producing a container. By means of at least one heating device (20, 30) the plastic material is heated to an elevated temperature at which the material crystallizes thermally. The supply of energy is discontinued once the material crystallizes at a speed entailing that the thus released effect corresponds to or exceeds that effect which departs from the material undergoing crystallization. The apparatus includes a mandrel (26) having a forming surface (24) which at an increased temperature is brought into abutment against a defining surface (18) of the bottom potion. The forming surface has a curvature which deviates from the curvature of the defining surface (18) so that during the initial phase of the abutment the forming surface is abutting against the defining surface only in a central area thereof. On continued displacement of material in the bottom portion in order to form the portion the size of the central area thermoplastic material intended for temperature-conditioning abuts against the forming surfaces. |
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DETAILED DESCRIPTION According to the present invention, thermal energy is supplied to the originally substantially amorphous thermoplastic material by allowing this to abut against at least one hot abutment surface of good thermal conductivity during one or more relatively short periods of time.
Each time the abutment against the hot abutment surfaces has ceased, thermal energy is, because of the poor thermal conductivity of the thermoplastic material, dissipated relatively slowly to the ambient surroundings.
According to the present invention, the material temperature is raised by at least one heating to a temperature region within which the crystallization speed, and, thereby, the thermal effect which is released within the thermoplastic material is at least of the same order of magnitude as that thermal effect which radiates from the material once abutment against the hot abutment surface or surfaces has ceased.
For example, for PET, it has proved possible to achieve a relationship between the thermal effect released within the material and the thermal effect emitted from the material which entails that the material, without continued abutment against hot abutment surfaces, retains the requisite elevated temperature for a sufficiently long time for the material to obtain the desired crystallinity.
When the material is substantially amorphous, the crystallization speed is, at a given temperature, at its highest but fades at unchanged temperature according as the crystallinity of the material increases.
The term substantially amorphous material is here taken to signify a material whose crystallinity at most amounts to approx.
10%.
According to one preferred practical application of the present invention, the material undergoes a crystallization cycle in which, once abutment against the hot abutment surface or surfaces has ceased, the thermal effect emitted to the ambient surroundings of the material is first less than, subsequently substantially the same as and finally greater than the thermal effect which is released when the material crystallizes
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