Method and installation for injection moulding a plastic article
OwnerRonaldus Joannes Cornelis Maria Kok, Michael Adrianus Theodorus Hompus +1inventors
InventorsRonaldus Joannes Cornelis Maria Kok, Michael Adrianus Theodorus Hompus, Marinus Franciscus Johannes Evers
Life of this patent
Estimating the term…
Abstract
A method for the injection moulding of a plastic article, such as CD or a DVD, comprises the following steps: the provision of a mould (1) having at least two mould parts (2, 3), the provision of positioning elements (9, 22) for positioning the mould parts (2, 3) with respect to one another in a nominal mutual spacing such that a mould cavity (6) is obtained, injecting a fluid material into the mould cavity (6) under pressure, influencing the positioning elements (9, 22) in such a way that the nominal distance between the mould parts (2, 3) is maintained when injecting the material (26) into the mould cavity (6) under pressure.
Claims27
Method for the injection moulding of a plastic article comprising the following steps:
- the provision of a mould (1) having at least two mould parts (2, 3) which can be moved with respect to one another,
- injecting a heated, fluid material (26) into the mould cavity under pressure,
- characterized by
- the provision of positioning means (9, 22) for positioning the mould parts (2, 3) with respect to one another in a nominal mutual position such that a mould cavity (6) is obtained, which nominal mutual position is adjustable during or directly after injection, and
- the provision of a control device (23) influencing the positioning means (9, 22) by rapid control action in such a way that the desired nominal mutual position of the mould parts defining the mould cavity (6) is adjustably maintained as desired when injecting the material (26) into the mould cavity (6) under pressure or directly after injection,
- the provision of measurement means for measuring the thickness of an article, and
- the adjusting of the mutual spacing of the mould parts (2, 3) by means of the control device (3) on the basis of the thickness measurement.
Method according to one of the preceding claims, comprising moving the mould parts (2, 3) a small distance towards one another during or following injection of the plastic material (26) into the mould cavity (6) under pressure, in order to compensate for shrinkage in the plastic material (26) during the cooling thereof.
Method according to one of the preceding claims, comprising influencing the positioning means as a function of the dimensions of the master disc (24).
Installation for injection moulding of a plastic article by means of the method according to one of the preceding claims, comprising:
- a mould (1) having two mould parts which can be moved with respect to one another,
- injection means (5) for injecting the hot, molten plastic (26) into the mould cavity (6),
- characterized by
- positioning means (9, 22) for positioning the mould parts (2, 3) with respect to one another in a nominal mutual position such that a mould cavity (6) is obtained, which nominal mutual position of the mould parts is adjustable during or directly after injection, and
- a control device (23) for influencing the positioning means (9, 22) by rapid control action in such a way that the desired nominal mutual position of the mould parts (2, 3) defining the mould cavity (6) is adjustably maintained as desired when injecting the material (26) into the mould cavity (6) under pressure or directly after injection,
- measurement means for measuring the thickness of an article, so as to adjust the mutual spacing of the mould parts (2, 3) by means of the control device (23) on the basis of said measurement.
Dependencies are inferred from the claim text.