Page 27 - MetalForming-Dec-2018-issue

Parts remain tabbed together until ready for removal. The punch separates them, followed by automatic removal via pneumatic grippers.
truck would move the pallet to a press brake where an operator would bend the three offsets, make the 90-deg. bend on the short edge, and rotate the sheet to bend the tabs on the long side. The oper- ator would then stack finished parts on the pallet and move them to the assembly area.
Now, a forklift driver places a stock of raw sheets on the automated system’s loading table, typically 200 to 300 sheets depending on size and thickness. The loading table then slides into position underneath the gantry. To eliminate dou- ble loading, a blast of compressed air hits a corner of the sheet while two of the loader’s 12 pneumatic grippers grab the corner and shake it. The gantry then loads the blank from the left side of the punch table, where three programmable
single-sided load/unload system to eliminate manual sheet handling, it can operate unattended until its metal supply runs out.
A CPA by background, McNamara knows his way around an ROI spreadsheet, but says he didn’t need one to evaluate the new equipment. “It was obvious,” he says, “that by having a machine that could load and unload itself, and perform secondary operations, the system was going to pay for itself very quickly. Automation was essential for meeting produc- tion goals, so it was a no-brainer.”
Since installation in early 2018, VSI has dedicated the system to producing sheetmetal parts for its American- series safe deposit box, made of 22-gauge galvanized steel.
“We need 5000 to 6000 shelves per month to meet demand,” says Cheney. “It used to take an operator about 40 hr. to make 1800 shelves. We now get those off of our new punch press without even needing an operator. Further, the cycle time for a complete part is within 1 min. of what it took us on our old punch press, and that was without any bends.”
Overall, Cheney estimates that moving to an automated system cut production time by 60 percent or more, as VSI now can produce 1800 shelves in 12 hr.
Enables Combined Operations
VSI’s more complicated sidewall parts measure 15 by 20 in., have three offset bends in the middle with two slots in each bend, a 90-deg. bend along the short edge with six countersunk holes, and three 90-deg. bends (all short tabs) with one countersunk hole each on the long edge.
Previously, operators would manually load a single blank on the press, punch the part, slots and holes, and keep the parts tabbed together. Once the sheet came off the punch, the operator would shake the parts out of the skeleton, stack them on a pallet and manually fold the skeleton. A fork
and relocatable clamps grip it.
After punching, countersinking holes and bending (more
details shortly), the loader’s pneumatic grippers lift a com- pleted wall off of the table and place it on a pallet, stacking walls consistently. After removing all walls, the press grippers pull the skeleton to the right and push it through a drop chute.
“Our punch can make progressive bends, so we now bypass the press brake completely,” says Tony Mendez Jr.,
This gantry runs unattended, loading blanks and unloading finished parts from the right side of the system.
Fabrication: Automation
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