Metal working – Method of mechanical manufacture – Assembling or joining
Reexamination Certificate
2000-10-02
2003-07-29
Vidovich, Gregory (Department: 3726)
Metal working
Method of mechanical manufacture
Assembling or joining
C029S464000, C029S466000, C493S343000, C493S472000
Reexamination Certificate
active
06598284
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method of preparing a system of converting tools in a stripping station in a converting press, the converting-tool system comprising at least one central stripping board and an upper stripping die with a stripper-holder plate.
The invention also relates to a presetting table for working the method. The invention also relates to an assembly of components comprising a stripper-holder plate and a set of strippers for preparing an upper stripping die.
Presses for converting compact cardboard or corrugated cardboard sheets for production of packagings usually comprise a number of sucessive stations in the press, through which the sheets travel in succession. Starting from an infeed device or feeder, the sheets travel at a timed rate through a diecutting station where each sheet is cut into one or more blanks which remain interconnected by connections and entrain waste pieces of sheet situated around and between them, a stripping station where the cutting waste is removed, and a blank separating station where the connections are broken, after which the blanks are stacked.
In the stripping station the cut sheet is placed on to a wooden board with apertures, i.e. the central stripping board, formed with a plurality of pre-cut apertures. The apertures are disposed opposite the waste pieces of sheet and have an overall shape corresponding thereto, with a somewhat larger outline. The stripping operation is performed by using at least one movable upper stripping tool which descends perpendicularly to the cardboard sheet and pushes the waste through the apertures in the central stripping board.
The upper stripping tool is frequently an upper stripping die comprising a wooden board on to which strippers are fixed by screwing, nailing or sticking at places corresponding to the waste to be stripped, the strippers having varying forms adapted to the shape of the waste, such as nails, pins, strips or blocks of wood. Preparation of such a stripping die requires lengthy, meticulous work by a die-maker, and a stripping die can be used for only a single cutting pattern. If the manufacturer needs to perform a large number of different recurring jobs, in small or medium series, a corresponding number of different stripping dies, each costing several hundred Swiss francs to make will have to be constructed and stored.
To obviate this disadvantage, Swiss patent application CH 1417/99 by the Applicant describes a universal stripping tool comprising a stripper-holder plate comprising a pair of identical metal sheets formed with a large number of perforations over their entire surface and mounted on a tubular frame. The strippers are chosen from among rectangular blocks comprising magnetic fixing studs and stripping pins in the form of a rod bent twice at right angles to form a U having two arms of unequal length inserted simultaneously into two pairs of perforations in the two perforated metal sheets and remaining held there by the relative elasticity of the two arms.
Patent CH-682651 describes a movable upper tool in a blank separating station, comprising punches carried by a board formed with openings through which air flows. The lower surface of the board is covered with a layer of “velcro” or similar hook-fibers. The upper surface of each separating punch is covered with a second layer of “velcro” or similar mating hook fibers adapted to engage the layer of fibers covering the board and securing the punch to the board. The punches are arranged in a manner corresponding to the positions of the connections between the blanks in a sheet. This tool is modified for each job and avoids the need to store a large number of blank separating tools, each corresponding to a given job.
Automatic converting presses are capable of processing several thousand sheets per hour. Short series of blanks for packagings themselves comprise only a few thousand articles. It is therefore essential for economic reasons to be able to change from one job to another, i.e. to prepare the converting tools and insert the tools in the machine, adjust them to size and secure them, without stopping the machine for more than a few minutes.
The actual operation for fixing the strippers and punches mentioned hereinbefore to their supports is brief but very tricky, since an error in positioning may result in jamming the machine. Preparation therefore requires laborious corrections.
SUMMARY OF THE INVENTION
One aim of the invention is to propose means for rapidly preparing the converting tools, more particularly the converting tools in the stripping station, during masked time, i.e. while the machine is carrying out a different job, by drawing from a limited stock of standardised components. Another object of the invention is to prepare the tools in such a way that they can be positioned in the station without requiring laborious adjustments. Finally, preparation should be as accurate as the work of a die-maker.
The invention therefore proposes a method of preparing a system of converting tools in a stripping station of a converting press comprising at least one central stripping board and an upper stripping die with a stripper-holder plate, comprising the following steps:
the central stripping board and the stripper-holder plate are disposed face to face outside the converting press and fixed in an adjustment position,
the strippers are fixed to the stripper-holder plate in line with the apertures in the central stripping board in order to form the upper stripping die,
the upper stripping die and the central stripping board are placed and centered in the stripping station.
The method can be worked according to the invention by means of a presetting table comprising a frame, bearing support means and means for fixing the stripper-holder plate, means for supporting the central stripping board in order to hold a central stripping board in contact with or near a stripper-holder plate, and means for fixing the central stripping board, chosen so as to fix a central stripping board in the adjustment position.
In the method according to the invention, the central stripping board serves as a template for rapidly and accurately positioning the strippers on the stripper-holder plate.
The presetting table according to the invention can be used to effect this operation in reliable manner without worrying about the respective positions of the stripping board and the stripper-holder plate once fixed to the table, since the table holds them in the correct adjustment position without risk of accidental displacement while the operator is fixing the strippers on the plate.
The user in principle need store only two stripper-holder plates, one in operation in the machine at work whereas the other is prepared outside the machine for the next job. A small number of plates is sufficient in every case.
Preferably, the strippers and the stripper-holder plate are designed so that the strippers can be placed and fixed to the plate manually and removably, so that their arrangement can be altered when required.
Preferably, in the adjustment position, the stripper-holder plate and the central stripping board are in the same relative positions, seen in projection on to a plane parallel to the central stripping board, as the positions which they occupy when placed in the stripping station, when they are centered laterally with respect to the machine axis and adjusted longitudinally to the first rule. If this adjustment position in the presetting table is adopted, there will be no need for an additional adjustment operation when the tools are inserted into the stripping station.
Terms such as “longitudinal”, “lateral”, “front” and “rear” are used here with reference to the direction of advance of the sheets in the machine. The machine axis is a virtual axis in the direction of advance, used as a reference for all adjustments of components of the converting press in the transverse direction.
The term “first rule” refers to the first transverse rule of the shape for cutting in the diecutting station.
In present-day conv
Chiari Mauro
Rebet Sylvain
Bobst S.A.
Omgba Essama
Ostrolenk Faber Gerb & Soffen, LLP
Vidovich Gregory
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