Page 24 - MetalForming June 2010

Tooling Technology
On the Shop Floor
• Use locating pins or die guides on the press bolster to allow consistently quick and accurate die setting.
• Standardize clamp pieces and store them with the dies or on the press.
• Standardize shut heights or, as an alternative, install automatic shut- height adjustment through your press control. Another related time saver is use of automatic air counterbalance adjustment.
Shopping for QDC Hardware
Once a stamper has implemented all or most of the above processes, con- gratulations! Now we can talk about what should be one of the last steps to improve job-changeover efficiency— the hardware.
Control box—A simple, compact, enclosed control box mounts where it’s most convenient, and controls hydraulic die lifters and clamps with just a key switch and a few illuminated buttons.
Hydraulic power units—The prop- er power unit supplies not only the cor- rect pressure, but also the number of circuits for the required or desired safe- ty level for equipment, tools and people.
Die lifters—Individual or array type, spring, air or hydraulically actuated die lifters lift and assist movement of dies on the press bed.
Bolster extensions—Dies can be rolled from the press bed onto remov- able, pivoting, or swing-down bolster extensions for easy retrieval by die- transport vehicles.
Hydraulic clamps—Although con- ventional clamp straps and bolts are inexpensive and adaptable, they take a lot of time to set up and do not consis- tently deliver high clamping force. A better solution often is use of hydraulic clamps, and metalformers have a wide variety from which to choose.
• Ledge clamps can be placed manu- ally in T-slots or bolted to the bolster or slide, and clamp directly on a flat clamp- ing surface.
• Rod clamps must mount in T-slots on the bolster or slide and U-slot cutouts on the clamping surface.
Bolster extensions such as the pivot- ing type shown here allow dies to be rolled on and off of the press bed for easy retrieval by die-transport vehicles.
Develop a list of specific improve- ment goals—The above times may seem extreme, and hopefully your change-overs occur more quickly than 81 min., but most stampers have room for improvement.
Assign responsibility—Make some- one, such as the press operator, setup person or foreman, responsible for implementing each improvement idea.
Train the other personnel—Dur- ing the planning phase, ensure that the core process-improvement team receives input from others involved in change-overs, to engage them in the process. After planning, document and post the proper procedures and conduct training sessions for all involved.
Track the improvements—Keep written, posted records of before and after results.
An efficient pressroom layout is a must. While rearranging the shop may not be possible, at least make it clean and uncluttered, to allow employees to move about quickly and safely during job changes. Immediately following the last hit on the current die, move parts and scrap bins, unloaders, and other appratus out of the way, so as to not impede the rest of the process.
Locate staging areas for tooling, coils and the like close to the press and have items prestaged in those areas well in advance of the last hit of the current die or coil. And, when not in a press or a staging area, store dies and coils close and convenient to the press area, with easy access to the dies by the transport vehicle. Keep the transport vehicle quickly available. Since the vehicle is often a forklift, which tends to get bor- rowed for other tasks throughout the plant, consider dedicating a forklift just for die changes. Or, buy a dedicated die cart.
Strive to have all dies designed with the same clamping height; better yet, mount all of the dies on subplates stan- dardized for clamping height as well as left-to-right and front-to-back dimen- sions. Standardization allows use of the same size clamping fixture for all dies. And, with standardized subplates, fixed die-locating pins can be used in the press bed for quick, accurate die locat- ing. Placing of clamps can be easier or possibly even automatic.
To standardize die mounting:
• Add external blocks (such as ears) to existing dies to obtain a standard clamping height.
• Machine die-clamping surfaces to a standard clamping height.
• Mount dies on subplates of a stan- dard thickness.
• Mount dies on subplates of a stan- dard thickness and standard dimen- sions, or perhaps develop a few standard sizes covering your complete range of die sizes. For example, establish a small subplate (60 x 30 in. perhaps), medium (84 x 48 in.), and large (144 x 60).
22 METALFORMING / JUNE 2010
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