Injection-moulding apparatus and mould for use in the...

Plastic article or earthenware shaping or treating: apparatus – Female mold and charger to supply fluent stock under... – With preform severing means movable relative to mold

Reexamination Certificate

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Details

C425S556000, C425S574000, C425S575000, C425S810000

Reexamination Certificate

active

06210148

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to an injection-moulding apparatus comprising a mould having a first and a second mould section, which mould sections are movable relative to one another between a first position, in which both mould sections are in contact with one another and define a cavity for moulding a product, and a second position, in which the mould sections are spaced apart to allow removal of the moulded product, the second mould section having a bounding surface at a side remote from the first mould section, with which bounding surface the second mould section is in contact with a base, and a movable punch being situated inside the second mould section, which injection-moulding apparatus further comprises means for moving the punch. Such an apparatus is used inter alia for the manufacture of optical information carriers such as, for example, Compact Discs. These are round discs having a center hole. This hole is formed by the punch.
BACKGROUND OF THE INVENTION
An injection-moulding apparatus of the type defined in the opening sentence is known from U.S. Pat. No. 4,185,955. The second mould section of said apparatus comprises the means for moving the punch. These means comprise a pneumatic cylinder in which piston is arranged to reciprocate a plate to which the punch has been secured. This cylinder is connected to a pneumatic control system via lines. If by means of this injection-moulding apparatus a product is to be manufactured which differs from the previously manufactured product the second mould section must be converted. For this purpose the mould section has to be removed from the injection-moulding apparatus in view of the space necessary for conversion. With the prior-art injection-moulding apparatus this is laborious and time-consuming because it is also necessary to disconnect pneumatic supply and discharge lines and because auxiliary devices, for example a hoist, have to be used since the mould section is heavy. This is an expensive operation because production is held up during the conversion. Since manufacturers wish to minimize stocks and wish to offer products in small series, the demand for small batches of a product increases. This leads to an increased conversion time in proportion to the production time, resulting in a rise of the product costs.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an injection-moulding apparatus of the type defined in the opening sentence, enabling the conversion of the mould to be effected more rapidly. For this purpose the injection-moulding apparatus in accordance with the invention is characterized in that the base has been provided with the means, situated externally of the mould, for moving the punch. This reduces the size and weight of the second mould section to be converted, so that no auxiliary devices are needed for the removal of the mould section from the injection-moulding apparatus. Moreover, time is saved because the number of lines to be disconnected is reduced.
An embodiment of the injection-moulding apparatus in accordance with the invention is characterized in that inside the second mould section there has also been provided an ejector for ejecting a sprue from the punch and the injection-moulding apparatus comprises further means for moving the ejector, the base having been provided with the further means, situated externally of the mould, for moving the ejector. If further moving parts are situated inside the mould, for example an ejector, it is advantageous that the further means for moving said further moving parts are also situated outside the mould in the base.
A further embodiment of the injection-moulding apparatus in accordance with the invention is characterized in that at the location of the bounding surface the punch and the ejector have each been divided into a first part situated in the second mould section and a second part situated in the base. Both parts of the punch and of the ejector are in contact with one another but are not connected to one another. This reduces the number of connections to be detached for removing the mould section. Since the punch and the ejector are divided at the location of the bounding surface the mould section can be removed from the injection-moulding apparatus by moving the mould section only in the plane of the bounding surface. It is not necessary to move the mould section also in a direction perpendicular to the bounding surface. This is advantageous in view of the time required for removing and replacing the mould section.
An advantageous embodiment of the injection-moulding apparatus in accordance with the invention is characterized in that the means for moving the punch comprise a movable piston situated in a cylindrical recess provided in the base. A further advantageous embodiment of the injection-moulding apparatus is characterized in that the further means for moving the ejector comprise a movable further piston situated in a further cylindrical recess provided in the piston for the purpose of moving the punch.
The invention further relates to a mould adapted for use in an injection-moulding apparatus in accordance with the invention.


REFERENCES:
patent: 4085178 (1978-04-01), McNeely et al.
patent: 4185955 (1980-01-01), Holmes et al.
patent: 5209889 (1993-05-01), Brown et al.

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