The present invention relates a stripper clip for use in stripping machines for producing card, paper or plastics blanks or the like.
A variety of products are produced from card, paper or plastics blanks that are typically made from plain sheets which are cut and creased before being folded into shape.
Typically, an outline for a product blank can be defined using, for example, a computer controlled laser or equivalent cutting device which can define outlines in either a single sheet or a stack of sheets. The outline can be defined as a line of weakening in which a number of frangible links (nicks) maintain the blank in position within the original sheet. When required, the blank can then be punched or stripped from the original sheet (or vice versa) leaving a peripheral piece of waste.
It can also be desirable for a blank to include internal apertures requiring waste pieces to be removed from within the blank. Again, respective outlines for these apertures can be defined using a laser or equivalent cutting device which can define outlines in either a single sheet or a stack of sheets—this can be done at the same time as defining the external outline of the product. Removal of waste product from within a blank is usually performed by feeding the blank through a stripping machine and punching the waste piece(s) through a die from where they are collected.
One type of stripping machine, available for example, from Bobst of Switzerland, can be loaded with: a moveable punching board comprising punching members, such as pins or blades; a fixed die board, having a major surface juxtaposed a major surface of the punching board; and, where the punching board comprises pins, a moveable bottom stripper frame disposed adjacent a surface of the die board opposite the punching member.
Each of these 2 or 3 boards is especially designed for the blank which is to be processed by the stripping machine with pins/blades located and apertures defined in accordance with the shape, size and location of waste pieces to be removed from the blank.
The die board is provided with machined apertures corresponding to the shape of the waste pieces to be removed from the blank. During operation, the punching board reciprocates between a refracted state, where its punching members are spaced apart from the die board and enable one or more blanks to be located between the punching board and the die board with waste pieces lying in register with corresponding apertures, and an extended state, where the punching members have passed through corresponding apertures within the die board having broken the respective waste pieces from the blank and driven them though the aperture where they can be collected along with any other waste pieces from the blank and other blanks.
Blanks can be fed through a stripping machine either individually, in stacks or they can form part of a continuous web which is cut into individual blanks after being processed by the stripping machine.
Where the punching board punching members comprise pins and no bottom stripper frame is employed, a common problem is that waste pieces may not be cleanly or fully removed from a blank. Such waste pieces are either carried away with the blank and so may require that a product be rejected or need to be reworked—or worse, a waste piece may become stuck within a die board aperture, so preventing subsequent blanks from being properly positioned within the stripping machine and so causing the stripping machine to break down.
In order to facilitate cleaner and more precise removal of waste pieces from a product blank, the bottom stripper frame includes a plurality of stripping pins which correspond with and lie in register with respective punching pins of the punch. The bottom stripper frame also moves from a retracted state, where it is withdrawn below the die board, to an extended state where each punch pin and a corresponding bottom stripper pin catch a respective waste piece while fixed within the blank. The bottom stripper frame then retracts in tandem with the advancing punching board until the punching board reaches its fully extended state. The punching board then begins to move back towards its retracted state and so opens a gap between the punching pins and the corresponding bottom stripper pins. This allows waste pieces which have been stripped from a blank by the combined punching pin and stripper pin to fall away where they can be recovered. The punching board then fully retracts to its retracted state to allow the blank(s) now stripped of its waste piece(s) to be fed from the stripping machine and for a new blank or stack of blanks to be fed into the stripping machine.
While bottom stripper pins are effective—assembling, mounting and dismantling of the bottom stripping frame is expensive and time consuming.
According to the present invention, there is provided a stripper clip for a stripping machine according to claim 1.
Embodiments of the present invention enable a 2-board stripping machine comprising a bespoke punching board and die board to operate with a similar level of reliability to a 3-board stripping machine including a bottom stripper frame. The boards can be accommodated in conventional stripping machines and are fitted in the exact same way. Indeed, no changes are required to the control of the stripping machine to accommodate die boards including stripper clips according to the invention.
Embodiments only require the definition of suitable cavities or sockets in the die board to accommodate the stripper clips, but this is readily achieved when designing the die board and does not unduly increase machining time. Indeed the stripper pins are extremely cheap to produce and certainly much cheaper than the pins required for a bottom stripper frame and may either be disposed (if they are worn) or re-used from die board to die board.
An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Referring now to
The stripper clip 100 has a hub 110 which is shaped to be inserted into a corresponding cavity or socket in a die board as explained in more detail below. In the embodiment, the hub 110 has a generally square outline, allowing it to be located in a socket with a pre-defined angular orientation—however, it will be appreciated that the hub can have a variety of shapes compatible with being inserted in a socket in a die board. Referring to
An arm 130 extends from the internal surface of the distal end 122 and is terminated with a ball 140, giving the clip a U-shape. The cross-section of the arm 130 as well as the material forming the clip 100 allow the arm to flex backwards and forwards towards and away from the hub 110.
Referring now to
Referring now to
In
As the punching board 200 moves further downward from the position shown in
The punching board 200 continues to move downwards towards its fully extended state shown in
Once the punching board 200 has returned to its retracted state, a new blank 400′ can be fed into the stripping machine to be processed as before,
Number | Date | Country | Kind |
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1607848.7 | May 2016 | GB | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2017/058712 | 4/11/2017 | WO | 00 |