GB2510158A - Robotic Structural Steel fabrication - Google Patents

Abstract

A system for fabricating structural steel members in which a beam is loaded onto rotators 2, 3 plates are plasma cut and held in stack 8 prior to alignment and fitting with the beam and welding thereto.

Description

DESCRIPTION

Structural Steel Fabrication concerns the manufacture of steel beams and columns for a framework that forms the skeleton of many buildings. Steel fabrication is a craft/engineering discipline which currently requires intensive highly skilled manual labour. The most advanced fabricators are automated to the extent that steel beams are cut and drilled in special purpose large machines called Drill and Saw Lines. Plates for fittings which facilitate on-site beam to beam connections are sometimes machine punched or plasma cut.

The remaining tasks of positioning, tacking and welding these fittings, remains a manual and skilled activity -this is the job of a steel fabricator. The Automation of these activities are the subject of this invention.

The invention is that of a totally integrated and Automated System for the fabrication of structural steel members.

More precisely it allows: a) Cutting, shaping and incorporation of holes and other features from a length of standard section of structural steel.

b) Cutting and Shaping of steel fitting plates of various thickness including holes and slots.

c) Locating Position and Orientation of Fitting Plates onto the steel member.

d) Welding Fitting Plates onto steel member. These may be on any face of the member of various sizes and orientations.

The overall system is portrayed on drawing BSG-01 which shows a Beam (1) loaded into Rotators (2&3) and ready for fabrication. Prior to this the Rotators are correctly positioned specific to the length of the beam shaft, taking into account any obstructing fittings on the beam -so that the need-be access by Robots (4&5) for positioning, orientation and welding is unhindered.

Typically Plasma Cutting Robot (4) will move along a slide (7) and plasma cut the plates held in a Stack (8).

The Stack hold plates of differing thickness Drawers which individually slide and retract as necessary presenting the plate to the Plasma Cutting Robot (4) Having cut the fittings, The Plasma Cutting Robot(4) rotates by 180 degrees and then cuts, shapes and holes the shaft which moves longitudinally as required along a servo-controlled track(9). The shaft is rotated by the Rotators (3&4) -to allow effective reach and correct face presentation to the Plasma Cutting Robot(4).

With fitting plates and steel member appropriately cut, a tool change is then carried out from Plasma Cutting to a Handling-Type End-Effector -either automatically or manually. Alternatively a 3rd distinct Robot -not illustrated -could be used to undertake this Handling Task which in effect positions the fitting onto the beam -which itself has been correctly moved & rotated.

With the fitting in the correct position and orientation, the Welding Robot proceeds to tack-weld the fitting onto the beam.

The Fitting, up to now being held by the Handling Robot is then released and the Welding Robot completes the welding operation.

The above sequence is not rigid, e.g. all plates can be first tacked and then welded at end of sequence -whilst the plasma-cutter can be preparing plates for next beam. Certain economies can indeed be achieved by ensuring that the Robots are multitasked, and minimising standing time of any one Robot to maximise productivity.

The Drawer Type Plasma Cutting Table, which is a key component of the invention is portrayed on drawing BSG-02 and consists of individual extending and retractable drawers containing stock size plates (5) of differing thicknesses. This particular design that can be varied consists of seven drawers (not all shown) holding plates of unique thicknesses. The drawers are opened and closed by electric motor and rack and pinion or other mechanism or by hydraulic or pneumatic actuators (7) -as partly indicated in drawing. The system controller determines state of drawers at any instant and any individual drawer (1) runs on its wheel guides (8) in a horizontal manner. When extended it presents the plate to a Plasma Cutting Robot or other mechanised Gantry Mounted Plasma/Laser Head.

The Plate, eg of 6mm thickness (6) sits on sacrificial slats(2) in the Drawer frame that are to all intents and purposes similar to a conventional Plasma Cutting Table. The Drawers are bottom open allowing heavy dust particles to fall into the Dust Tray (4). The system is Shrouded by Sheet steel (3) allowing negative pressures for effective and efficient extraction of fumes and dust -not shown.

The other key component of the invention are the unique Beam Rotators portrayed on drawing BSG-03 and consists of a steel frame (1) onto which are mounted moveable parts that hold and rotate the structural beam -a small segment only of which is illustrated (2). The Beam is retained vertically by a retaining bar (3) and/or a flange clamping device (4). Horizontal Slots (5) facilitate a range of beams from smallest stock length to largest depth -simply by appropriate repositioning of the retaining bar, and tightening of hand-clamps. Horizontal positioning and retaining, is done via a bottle jack (6) or other type of actuator. An open gear and support guide ring or a composite of both (7) allow the beam to be loaded and rotated by pinion(8) attached to motor and gearbox. Should accurate and continuous control be required a servo motor can be used. Alternatively for discrete control at say 22.5 or 45 degree intervals, proxy switches or encoder feedback can be used for stop signalling an induction motor.

The Rotator shown allows the beam to be from -90 degrees to 180 degrees -allowing all faces of the beam to be presented and worked on by the robot positioned as indicated on Drawing BSG-01.

Although the Rotator indicated here is part of an Integrated system with incorporated Axial Control via a Servomotor (9) driving Rotator and Beam along a rack (as shown in BSG-01) , it is conceived that this could be dispensed with, and the Rotator could be particularly useful in its own right mounted onto a conventional static bench allowing a Steel Fabricator to rotate and fabricate a beam at will -without being repeatedly reliant on workshop craneage -other than for initial installation & final removal.

The unique features of this system is that a beam is vertically placed and extracted from the Rotator which itself takes up a minimum of axial space -called here the Dead space (8)-allowing more of the beam to be worked on and without the progressively attached fittings affecting the rotation operation.