December 14, 2017

Cellular Phone Cover Assembly Machine


This machine assembles cellular phone windows onto self-adhesive gaskets and applies a protective label.  The gaskets are supplied 5 up on sheets of backing paper and are loaded by the operator onto fixtures on an over and under servo-driven indexing conveyor. The windows are supplied in vacuum formed trays and are loaded by the operator into an automatic tray progression system. Empty trays are discharged into a pile at the end of the machine. The indexing conveyor makes 4 short indexes between gaskets and then 1 long index to get to the next sheet. The windows are loaded onto the gaskets by a 4 axis servo controlled parts placer.  Even though the accuracy of the indexing conveyor is pretty good, the position of the gaskets on the paper and the position of the windows in the tray is not repeatable enough to achieve the window placement.

Each window is visually located with a CCD camera connected to a PPT vision system prior to being picked up and the gasket location is also verified visually before the window is put down. Once the windows are loaded onto the gaskets, they are seated with an air cylinder press and a protective label is applied by a standard labeling machine.  Bad assemblies are identified with an ink mark. All strips of release paper, gaskets and windows are unloaded onto an output conveyor that takes them to the next operation.

MACHINE CONTROL – The machine is controlled by a pair of Intel-based PC’s. The main control computer is a 10 slot passive backplane computer with a 486SX-33 processor. It has one 5 axis DSP based motion control board that control the motion of the 4 servo parts placer axes and the indexing conveyor servo motor on the machine, one TMS 34010 based vision system board and a GE PCIF card used to communicate with up to 4 racks of GE 90/30 Input Output modules. This computer actually controls the real-time operation of the machine using a custom C++ program running on DOS 6.2. The other computer is a 75 MHz Pentium PC running Windows 95 that provides the Man-Machine Interface and data collection. This computer has a touchscreen monitor and runs a custom Microsoft Visual Basic 3.0 program to interact with the operator. The two computers communicate over an Ethernet network cable.

ROBOTS – The window loading station uses four-axis Cartesian coordinate robots made up of Intelligent Actuator servo-driven ball screw slide modules. Each axis module is repeatable to +/- 0.0004″. All modules are heavy duty and are doweled or keyed together to preserve alignment if they are disassembled for repair.

CYCLE RATE – This machine processes 15 windows per minute.

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