Solution for Drilling Holes in Auto Chassis Long Member

Yes, but for series consider a Hydraulic multi- punch portable press. You can also have the holes positioned for repetition.

You can't punch the holes. Unless you can put a back-up plate behind it. Inside the member.

Laser, or gang drills would work. Don't know about water jet. It may go through the other side, too. I've seen steel railroad rails cut with water jets.

Sorry if I am wrong, but I have only worked on U- shape truck members. The punches had a C- model arm like a micrometer.

OK - my fault that I did not give the complete picture. Let me do it now. At this point the part is flat - not yet formed into C shape. When it is punched on a heavy duty hydraulic press sometimes the smaller punches get broken resulting in some holes missing in the part. There is a vision system at the exit of the press which detects missing holes. Often when a missing hole is detected the press is stopped, the broken punch changed and operation continued. However, sometimes (especially for some special configurations) the die may not be designed to hold a punch at the proper location. This happens when the manufacturing guys use the 'nearest' die. Or, it may not make much sense to stop the production flow for the sake of just one or two missing holes. These missing holes are then drilled at a 'rework station' downstreeam. This process of 'rework' is to be automated under an improvement program. The vision system would give the missing holes information to the drilling system which is supposed to drill all the missing holes.

We produced a similar system from Romanazzi for Henschel Engineering. The steel came (yes) in coils and ran through an endless series of rolls until the shape for the chassis had been obtained. The process was running and all the holes were punched online with moving presses, doubled just for the accuracy. Even the length was cut while running with a moving shear. IF you want to drill make sure you get a magnetic base on your machine. Usually these holes get punched.

Sorry,

You may be right. My pickup has boxed frame rails.

How about adapting a bazooka? (Just shoot a bunch of holes in it.)

Similar to the LynDoor™ EHAT process:

Since you have already ruled out proper process control and "fault proofing" the original manufacturing step by fixing punches when they break there seems to my history only one robust solution.

A press with a single punch tool of the correct diameter with necessary stops and fence to control metal position before press activation and properly aligned bottom half on presstool (Guided pillar tool).

In this instance, you might even make a spare tool to exchange when this punch eventually gets chipped/dull.

I suspect though that your management have shown their treu form and that eventually this process stage will have to punch every hole as they are too lazy to put the effort into getting it right first time, but are prepared to spend time and effort on a rework that will be less precise than the original process and this probably doesn't have the fault detection inbuilt, so a missed hole here will eventually get tot he customer.

If it's just flat and no obstructions a turret press.

What dimensions are the holes where the punches are breaking? This should not be happening in my experience. May be a design flaw in the punch or in the shape of the punch. My operation was punching 10mm hole in8 mm material for years and never broke a punch but when we could hear the press changing tone we had the punches sharpened and they always provided an angle on the cutting edge to ease the punch into the metal.

There are a large number of holes in the part - usually around 250 but the number goes up to 500. Smallest hole is of diameter 7 mm. All holes are done in one stroke. Obviously the punch / die is the same length as the component. The die guys are providing an angle on the punch - though I don't know what that angle is.

In your OP (original post), you said "...for making around 15 holes of dia 16 in 1 minute." This is about 3,000 mm² of material, 7mm thick, in one minute.

Now you say "...usually around 250... Smallest hole is of diameter 7 mm." If we use this information, I get about 9,620 mm² of material, at the minimum! "...All holes are done in one stroke." One stroke of a press? And these dies are 10 meter long?

Clarification, please.

Yes - the dies are 10 meter long. Though there are usually around 250 holes in the part only the ones which are missed are to be done as rework or rectification. There are two reasons why these holes get missed:

1. We need to make a few parts (say up to 25) with a special configuration - a few extra holes. These are not present in the original die. Obviously, it is impractical to manufacture a special 10 meter long die for the sake of a small batch

2. A punch may get broken during the punching operation. While many of the dies allow in place replacement of broken punches some others of the dies are designed differently and do not allow it. Which means you need to take the die off the press, replace the broken punch and reload the die. Since this may take a few hours the production guys avoid it and knowingly produce parts with a few holes missing. These parts are marked and reworked separately. As some of the guys on the forum have said this is not the right thing to do - but....

Do you work that sharp on calculations (strength?) that all the members can not have the "extra" holes? If the holes are such a problem during the next phase, it could be a lot easier to rivet these when the frame gets completed.

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Bringing the members to a laser with X-Y table, and adjusting everything, takes also time. A CO2 laser is costly to operate too and not portable.

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If you work with templates, a portable plasma will work out a lot more practical.

Is this a new or recent issue has it been there all along? If the metal being worked is extra tough you may contact the supplier of the punch tooling and ask for suggestions, I always leaned heavily on my suppliers for technology where I was lacking. How many strikes per second or minute are you attempting? Is the material sitting firmly on the backing sufficient to prevent bounce or vibration? Lubricant on the punches is critical from my experience. Is the material held down firmly to prevent withdraw interference? Most or all of these issues were experienced when I was working both mild steel and aluminum.

I'd invest in a CO2 laser. Much faster and very precise.

Thanks everyone. I am concluding that laser cutting is the solution to go in for.

Some final suggestions re the punches. Is it the same size punches failing and the same location? What is the frequency of breakage? 100 cycles? 200 cycles? if there is a pattern it may be the punches are working at or near their limit and can be changed out before they break when the machine is down for any reason. I would also definitely look into a different brand of punches and give new vendor full disclosure as to the issues. Could save big bucks on a patch-up solution vs correction of a problem.

1. Generally only the smaller size punches (smallest hole is 7mm and largest 70mm) fail. There is much variation in the failure frequency. I guess this is because the size of the die and even small errors in alignment would result in breakage of the smaller punches. Our manufacturing / tooling guys have not been able to establish a pattern. So we do not really know if the punches which fail are working near their design limit. Care is taken to ensure that the smaller punches are inspected and replaced if necessary while loading the die.
2. Your point about savings in finding a solution which takes care of the root of the problem is well taken

Good luck I think you have been given a lot to think about.. you might also take a good look at the raw sheet it may have laps and inclusions that can cause issues. Seen that on some bad off shore material in the past.