Plastic article or earthenware shaping or treating: apparatus – Plural sets each comprising a female mold and opposed... – Molds or press members traveling transversely to molding motion
Patent
1996-06-06
1997-12-16
Woo, Jay H.
Plastic article or earthenware shaping or treating: apparatus
Plural sets each comprising a female mold and opposed...
Molds or press members traveling transversely to molding motion
425353, 425434, 425DIG35, 425435, B30B 1108
Patent
active
056982380
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to the production of aggregates by compression of powdered or granular material.
In particular, the invention refers to a rotary tabletting machine that produces tablets by means of pairs of opposite punches driven by adjustable groove cams.
The subject tabletting machine carries out a new operative method of compression.
BACKGROUND ART
In the prior art there are known various rotary tabletting machines, which produce tablets from powdered material and which include only one turret driven to rotate around its axis.
The turret has means joined thereto for positioning and batching the material to be compressed, for compressing the material and for ejecting the tablets: see e.g. U.S. Pat. Nos. 2,989,781, 3,677,673, 3,999,922, 4,108,338, 4,943,227.
It is also known that the production of one tablet by a tabletting machine comprises a sequence of steps, that is, a step in which a suitable opening is filled with an appropriate quantity of material to be compressed, a step in which a prefixed volume of material is batched in the opening, optionally a precompression step, and then the subsequent compression of the material, with consequent formation of a tablet having determined thickness. Finally, a step occurs in which the tablet is ejected from the opening.
All the above mentioned steps take place during respective angular sections covered by the turret in a rotation round, and each working cycle can be carried out in a complete round or in a less extended rotation.
The pre-compression step has the purpose of reducing the problems resulting from the fact that the tablet, in its interior, keeps small quantities of air that can provoke microfractures, flaking or even explosion of the same tablet during ejection.
A tabletting machine that performs the precompression step is known from European Patent 0,204,266.
In some cases, a further improvement has been subsequently obtained by keeping the precompression load constant for a predetermined period of time, longer than normal precompression and compression time.
The load is usually kept constant by the action of compression means, constituted by pairs of opposite punches. The outer heads of the punches slide along stationary guides (sliding blocks) for a pre-established angular section of the rotation of the turret.
This, however, can cause irregular and early wear of the punch heads, resulting in the necessity of more frequent substitution thereof.
Alternative or complementary methods, like the addition of binding materials, have been applied in order to limit the above mentioned problems, but they have not managed to resolve them completely.
For example, in the machine illustrated by applicants U.S. Pat. No. 4,943,227, the material positioning and batching means include a plate, rigidly connected to the turret in its central part, and features a series of filling openings, made by as many through holes.
The through holes are angularly equispaced along the periphery of the plate and have their axes parallel to the axis of the turret.
For each opening there is a pair of opposite punches which are slidingly guided by respective through holes in the turret. The punches, and the opening are coaxial.
The operative heads of these punches are inserted in the related opening and the mutual distance between them is changed in such a way that it is possible to carry out, in synchrony with the turret rotation, a series of cyclical operative steps for the compression of powder material.
Each of the punches is driven by means of a respective roller that is fastened to a side of the punch and runs along a specially shaped groove cam, integral with the tabletting machine frame
The feeding of the opening with the material to be compressed is made, in the example herein described, from a tank situated in the upper internal part of the turret, and takes place by means of channels made in the tank in correspondence with each opening.
The channels are fed continuously because of the centrifugal force due to the rotation of the same tu
REFERENCES:
patent: 3663147 (1972-05-01), Maekawa et al.
patent: 4057381 (1977-11-01), Korsch
patent: 4408975 (1983-10-01), Hack
patent: 4943227 (1990-07-01), Facchini
patent: 5211964 (1993-05-01), Prytherch et al.
patent: 5350548 (1994-09-01), Hinzpeter et al.
patent: 5462427 (1995-10-01), Kramer
I.M.A. - Industria Macchine Automatiche - S.p.A.
Leyson Joseph
Woo Jay H.
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