Dispensing – Jarring and/or vibrating
Reexamination Certificate
2000-03-27
2001-07-10
Shaver, Kevin (Department: 3754)
Dispensing
Jarring and/or vibrating
C222S199000, C222S488000
Reexamination Certificate
active
06257456
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention concerns a powder device for powdering printed sheets, comprising a powder container containing powder and from which powder is extracted, wherein the powder device is designed as an exchangeable container which can be removed from the powder device and which has an opening at its lower end which can be closed by a closing element.
There are a plurality of conventional powder devices of this kind. DE 22 52 474 A discloses e.g. a supply container for powder, wherein the lower opening forming the outlet can be closed by a ball. Containers of this type have, however, the essential disadvantage that they are relatively easily blocked, since the powder sticks to the side walls or powder bridges are formed thus preventing further supply of powder from above. GB 15 88 393 B discloses a container having an elastic bottom which is moved via a vibrator. The powder is not drawn off from this container via a lower flow opening, rather suctioned off using a suction air flow. This also has the above-mentioned disadvantages, since the powder adheres, in particular, to the walls and can no longer continue to flow towards the suction nozzle. U.S. Pat. No. 4,051,981 discloses a powder device having a bellows-like supply container, opening into a pin-cushion from which powder can be blown into a blowpipe by compressing the supply container. This device prevents sticking or formation of powder bridges, since the supply container is continuously elastically deformed.
DE 38 11 309 also discloses a supply container for powder, wherein the lower outlet opening is closed by a ball. When powder is required, the ball is pushed into the supply container by an actuating element to loosen up the powder located above the ball which can then flow past the ball in the direction of the outlet opening. Compressed air is blown into the supply container to further loosen up the powder. The container must be sealed in an air-tight manner to prevent the powder from escaping from the supply container.
It is the underlying purpose of the invention to provide an exchangeable powder container which reduces powder build-up on the container walls and which reduces powder bridge formation in the container.
SUMMARY OF THE INVENTION
This object is achieved in accordance with the invention by a finger or dome extending into the inside of the container above the outflow opening.
The lower end of the powder container in accordance with the invention has an outflow opening for discharge of the powder. A finger-like dome is disposed above this outlet opening and is rigidly connected to the powder container. This dome protrudes into the powder in the container to substantially prevent formation of bridges and columns in the powder container and to effect uniform flow of the powder. The vibrations occurring during operation normally cause sufficient shaking of the dome, via the powder container housing, to loosen up the powder and maintain free flow thereof. This also prevents sticking of the powder to the inner walls of the container.
With containers having a truncated cone-shaped lower end passing over into the outflow opening, the dome preferentially has a length or height which is greater than or equal to the length of the truncated cone. The critical area in which the powder is usually compressed, is thereby penetrated by the dome to assure loosening of the powder in this area.
In an advantageous embodiment, the dome has the shape of a sleeve. The dome thereby has a vertical longitudinal axis and extends, in particular, along the axis of the powder container. The sleeve shape has the substantial advantage that the powder can flow through the dome itself. Towards this end, the dome has several transverse bores for passage of the powder into the dome. Powder flow into the dome leads to additional loosening up of the powder supply. The powder in the dome is discharged via the outlet opening. The dome is preferentially disposed such that the powder must initially flow into the dome before reaching the outlet opening.
Advantageously, the upper side of the dome has a pointed tip at the end of the upper side of the dome for distributing the powder, in particular, for breaking-up powder clots located above the dome.
Advantageously, the dome extends over 10% to 80% of the height of the powder container. The dome can thereby be disposed in the container in an exchangeable fashion. This permits e.g. use of different dome designs for different types of powder.
In a further development of the powder container, the closing element is formed as a flap extending away from the output flow opening. This flap closes the container opening from the outside and is withdrawn when the powder container is opened. This has the essential advantage that the powder in the container is not additionally compressed when the powder container is opened and relatively little force is required to open or move the flap. When the container is opened, it can be easily closed again by seating the flap on the outflow opening.
In one embodiment in accordance with the invention, the flap is supported pivotably, in particular, on the powder container. It is also feasible to design the closing element as a slide element which opens the container opening via a sliding motion.
The flap is preferably disposed on the opening under the force of a restoring spring, wherein the spring force closes the opening. The spring force is thereby sufficiently large that the flap does not open under the weight of the powder. Moreover, the flap prevents outflow of powder, in particular when the container is replaced or filled.
In a preferred variant of the invention, the flap can be actuated by means of a drive. This drive is disposed at the powder container receptacle and is designed, in particular, as a tappet drive. Other drives are feasible, e.g. magnetic drives, pneumatic or hydraulic drives or the like.
In one embodiment, the flap comprises a spherical body for sealing the opening of the container. This has the essential advantage that the opening can be sealed to an optimum degree and the discharged powder can easily flow around the flap. Powder, which could impair re-sealing of the container, does not remain on the flap.
Preferably, the powder device comprises a quick-connect means for securing the powder container. This quick-connect means facilitates easy and fast removal of an empty powder container from the powder device for either re-filling or replacement with a full powder container. The removal or mounting of the powder container can be done without tools.
Improved loosening of the powder within the container via the dome can be effected by connecting the powder container to a means for setting it into vibration, in particular a vibrator. This vibrator may be operated either continuously or in defined intervals. The vibrator may thereby comprise e.g. a counterweight or a magnetic oscillator.
Further advantages, features and details of the invention can be extracted from the dependent claims and the following detailed description of a particularly preferred embodiment with reference to the drawing. The features shown in the drawing, recited in the claims, and delineated in the description may be essential to the invention either individually or collectively in arbitrary combination.
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Deal David
Shaver Kevin
Vincent Paul
Weitmann & Konrad GmbH & Co. KG
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