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A new, fully automatic machine for the decoration of flatware articles has recently been introduced to the market. The machine automatically transfers heat-release decals, printed with ceramic colors, in an exact fit onto flatware items. Unlike conventional heat-release machines, the new system can recognize contours and angles, making it suitable for use with round, festooned and angular flatware, as well as other unconventional shapes. The complete decoration process is automated—from placing the undecorated stacks of flatware items on the buffer belt to the unstacking, printing and bottom stamping processes, the feeding of interleaf papers, and the final stacking of the decorated articles for further handling.
Supplying and Positioning the FlatwareThe stacks of flatware items are placed on the buffer belt and transported to the lifting fork of the unstacking device. A sucker separates the pre-positioned flatware stacks on the buffer belt and transfers them to a three-point centering device.
Next, a lifting and rotating unit takes each item from the centering device. This unit is installed on a servo-linear device, which takes the item to the article positioning and recognition station. In this station, a servomotor rotates the item 360 degrees, enabling a high-speed laser scanner to determine the turning position, as well as the x and y mismatch of the item. The item stops in a pre-determined nominal contour position in an exact angle. The servo-linear unit conveys the positioned item to the article table in the heat release station, and the deviation of its position from the y-axis is corrected before the article is transferred. The position deviation of the x-axis is adapted during the movement of the article table into the printing station.
Positioning the Decals for Thermal ApplicationWhile the piece of flatware is being recognized and positioned, a vacuum sucker on the linear transfer unit takes a heat-release decal from the magazine and deposits it on a temperature-controlled vacuum table, which rests on a coordinate table. Once on the table, the decal is fixed by vacuum and then measured by a camera located in the vision system. Points that are printed outside the actual decoration with a high contrast decoration color are automatically recognized, and any deviation from a given nominal position is corrected by the coordinate table. This correction is done while the coordinate table is moving underneath the printing pad of the decal transferring station. If necessary, the position for displacing and turning the decal can be adjusted in steps of 1⁄10 mm at the operating terminal.
The printing pad, driven by a servomotor and already heated to its working temperature by infrared heating, is lowered onto the vacuum table where it picks up the decal. The printing pad and the vacuum table then return simultaneously to their initial positons. During this movement, the body paper is automatically removed, and another decal is deposited in its place.
Decal Transfer and Back StampingIn the printing station, the printing pad transfers the decoration to the article, which is held in place by vacuum. The article table then returns to its initial position, ready to be unloaded and accept a new article.
Once it has released the decal, the printing pad is restored to its working temperature through infrared heating, provided by optical temperature sensors, and a new transferring cycle is started.
A second servo linear unit picks up the decorated article from its initial position at the article table and takes it to the backstamping station, where the article is stamped and then placed on the lifting fork of the second plate-stacking device.
Conveying the Flatware with the Stacking DeviceSucker lifting units take the protective papers, which are stored beside the second stacking device, and deposit them individually as interleaf papers on the decorated articles using a pneumatic linear unit.
The lifting fork moves downward by one article height with each movement, so that there is a constant take-up level for the top article in a stack. This process is repeated until the desired stack height is achieved. The lifting fork then moves to its lower final position and deposits the stack on the conveyor belt, which conveys the stack away from the working range of the lifting fork. The lifting fork returns to its final upper position, and the working cycle begins anew.
As soon as the conveyor belt has been filled with flatware stacks (i.e., the buffer storage is fully loaded), the working process of the plant is stopped. This guarantees that no flatware items are thrown off.
Programmable ControlsA programmable control unit is integrated into the machine to control all elements of its operation. The parameters are entered in an operating terminal and are stored in the control unit so that they can easily be called up for the different articles and decorations produced. Programs for up to 100 different articles can be stored in the system.
The operating terminal features a keyboard and integrated display and provides the following features:
- a clear menu control and easy curser handling
- a detailed and automatic failure display
- the ability to call up and display the current operating conditions
- the ability to manually control and display certain functions
- the ability to call up and change all parameters during automatic operation
- the ability to copy and vary any of the programs stored in the system’s memory
- total number of pieces
- number of pieces per article
- hours of operation
- total production time
- breakdown and change-over times
The new technology gives manufacturers and decorators a new level of flexibility and efficiency in automated decoration. The first of these new machines are expected to be installed by the end of this year—and others are sure to follow.
For More InformationFor more information about the new heat release technique, contact Thuringia Netzsch, Gebruder-Netzsch-Str. 19, D-95100 Selb/Germany; (49) 9287-886-0; fax (49) 9287-886-189; e-mail firstname.lastname@example.org; or visit http://www.thuringia-netzsch.de.
SIDEBAR:Performance Characteristics of the New Heat Release MachineMaximum capacity for round plates = 400 pieces/hour
Maximum capacity for plates in other shapes = 300 pieces/hour
(depending on the shape and size of the article)
Diameter of article
max. = 360 mm
min. = 100 mm
Maximum height of article = 100 mm
Maximum diameter of decoration = 400 mm