20501 Hoover St, Detroit, MI 48205 Tel: (313) 839-9300 Email: email@example.com
INSPECTING STRAIGHT SIDE DOUBLE CRANK PRESSES By Chip Thornton, CEA
Presses come in all shapes and sizes. Each is used for the pressing of metal, plastics, and sometimes even cloth or wood. I am going to focus on just one segment of the press industry and stick to Straight Side Presses. Even just saying this, we can get into several sub-categories. However, we are going with straight side double crank presses. When buying a used press, the big concern is how it has been used. Presses can be used and abused. Presses can break and this is the kiss of death to a press.
When inspecting a press, sometimes it can be overwhelming. A straight side double crank press can be 4 feet tall and a 600 ton to 2000 ton can be 35' tall and go into a pit another 20 to 30' feet. If the press is running, you can feel the vibration hit in the floors and vibrate throughout the entire plant. Sometimes when I pull into the parking lot of a stamping company, I can feel the pounding outside. That is when you know they have some large presses. When you walk up to a straight side press in a plant running, always note where the light curtains are located. Ask the operator or manager to stop the press cycles so you may approach and start with your confirmation of specifications. Most times, the manufacturer’s plate is still intact and it will provide you with the important details. The item to confirm when inspecting a press is first the stroke. This is the length the ram will travel. Remember that this is a used machine and it was ordered to fit a job. The company that ordered it may have requested a specific stroke length. It may be smaller than it should for the size of the press. High speed presses will have shorter strokes, and larger automotive style presses will have larger strokes. Shut height is the die clearance. Strokes per minute is an important detail for production. The press market has come a long way in speeding up large machines. Time is money. The next step is to get the bed and ram size. This is measured in length and width. It is always good to note the bolster information. Also note the length and width. It usually is the same size of the bed area. Check for T-slots. The press may or may not have windows. This is the opening in the uprights. It is important to measure the width and height. It is always good to have a heavy duty flashlight with you during inspection. Check all bearing surfaces for scores and gouges. Check all gibing for wear and make sure adequate adjustment of slide. Look for parallelism with a surface gage when possible. Sometimes the plant can do a jack test for you. This will let you know of any internal problems in the ram and crown. Stand back and visually walk around the press and be sure to check for cracks or welds. Once a press has been broken, it can be repaired. However, most buyers shy away even if it was professionally repaired. Always ask if the press has a cushion in bed. They are hard to inspect because they are buried in the bed of the press under the bolster plate. If the plant has a basement for the presses, go into the basement and do a visual from underneath as well. Note any electrical improvements. Look in the electrical panel and it will tell the whole story. Look for a good lube system on the press.
Have the operator cycle the press for at least a minute. Stand back and watch the ram go up and down. Look to see that it comes down level. Listen to all the gears. Listen for grinding noises that do not sound smooth. Try to get a good video of the press so you can review again at a later time. Do not get too close and be aware of light curtains. Never hesitate to ask the owner if the press has any cracks or welds. They can be painted over and hidden very easily.
Primary Parts of a Straight Side Press
When inspecting a used stamping press that has been dismantled prior to your inspection, look for all the parts. The press breaks down as follows: • Bed - the foundation of the press, providing rigid stability and support for all the other parts and the dies. • Uprights - columns that support the crown of the press. They direct the slide in precision gibs as it compensates and housed the press – controls and counterbalance cylinders. • Crown - houses the press drive mechanism and the joins the uprights at the top of the machine for rigidity. • Tie rod - make the heavy tension tie the crown and the bed together, resisting forces that tend to separate them as the slide closes. They are located at each corner of the press and pass completely from top to bottom. It’s important to know that some straight side presses do not have tie rods. • Crankshaft - in a fixed position rotates and through gearing causes the pitman and the slide to reciprocate. • Pitmans - used in connection the crankshaft and the slide. • Clutch - the coupling used to connect and disconnect the flywheel from the main shaft. The brake stops the press after clutch is disengaged. Don't hesitate to call our team at Presses for Industry to talk about your current and future needs. We handle all brands and tonnages of presses. We handle OBI, Gap, Hydraulic, Spotting, Straight Side Double Crank, Straight Side Single Crank, and Large Transfer Presses. We sell one machine or an entire plant. Some presses are very large to move. Let PFI sell your press direct to another end-user. This saves on large handling costs. PFI is completely global. We have offices China (Shanghai), India (Pune), and we are based Detroit, Michigan. PFI is currently liquidating the Ford Genk Plant in Belgium with tonnages up to 4000 ton Transfer Presses.
Please go to our website and see our full inventory of presses. About the Author: Chip Thornton has been in the business of buying and selling Stamping and Fabricating Machinery for 37 years. Chip is the President and is based in Detroit, Michigan. PFI has over 60,000 square foot of facilities with up to 40 ton crane capacity. PFI is a proud member of the MDNA, AMEA, EAMTM. 12
Specializing in Used Mechanical & Hydraulic Stamping Presses, Fabrication, CNC and Tool Room Equipment BUY – SELL - CONSIGN - APPRAISE – AUCTION & LIQUIDATION SALES 2 Warehouses with over 60,000 Sq Ft Heated, Machinery Available Under Power for Inspections
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