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Messages - zafarsalam

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161
Build Thread

I am back in Karachi after spending a week in Lahore and Gujranwala, an hour and a half flight from here. Informed the customer that the work is underway and we'll be able to deliver the planer stucture within a month's time.

Called Mr. Iftikhar two weeks later to get update on the progress of overhaul. His cell phone is off. Contacted his manager and he informed me that he is out of country on some business visits. Asked about the progress of our job and he says that he has no work instuctions on that. I get his number overseas and contact him there. He says that he'll be back soon and start working on our job. We are still within our job's time limit of 4 months, so no need to panic.

We start working on the control panel box and the servo motors' mounting fixtures for this job. Another customer's Turret Punch retrofit is underway in Karachi. He is fabricating control box for his machine. We request him to make 2 of those. The box arrives at our workshop in 2 weeks' time.

In Sadiqabad, where our client is, the summer time temperatures go up to 50 oC (122 oF) so a panel A/C is must for the drives and electronics. Inquired about industrial panel A/C's and again budget goes out the window. Decided upon installing compact window A/C unit in our panel. It is big enough to accomodate it.

162
With the planer table procured and despatched we head on towards the drawing board again (which is actually an Autocad based PC with internet). Now this one is hard. How to get the size of a ball screw which won't buckle under the load. Remember, the job's weight can be upto 2.5 tons. The moving table itself weighs nearly 5 tons and is sliding on v-shaped guideways which are 3.5 meters long. Where do we start?

THK website gave us some figures to start with when we were desgning the table with linear guides. It suggested a ball screw of 50 mm dia with 6mm balls and 10mm pitch for the loads and speeds we selected. The weight of table was comparable to this one but again those were linear guides and this is V-guideways with cast iron sliding against cast iron. Ok, let's compare our structure with other machines close to this size and weight. Customer happens to have a horizontal boring mill with a 3 tons table sliding on box slides (see photo). The screw there is 50 mm too.

A 70 mm dia ball screw having 2.5 m travel is available in the local market in Lahore. That would do the job. Buy it and ship it to Gujranwala too. Screw and nut weighs almost 100 kg. Comparable to that a 40 mm screw would be enough for the X-axis as we could push the drill head on radial arm by hand when it's gears are disengaged. Buy it too and include it in the package.

5.5 kW AC servo motor and drive selected for Y-axis, 3 kW for the X-axis and 1 kW for Z. Shipped these to the customer.

Mr. Iftikhar in Gujranwala will now take care of the Y-table. He'll give the slides an overhaul and install the 70 mm ball scews on it. After that he'll make mountings for the 5.5 kW servo motor on it which we'll install when all this setup reaches the customer's location. Sounds simple? No, it wasn't. This we'll find in the next post.


163
Eagerly waiting for more posts on this project! 

Love it!

That step under the Y bed...I believe it is a step to get better access to the table...
I need one of those in front of my tool chests to peer into the top drawers without standing on my toes. :)

The step under the Y-bed is the extension of it's foundation. Y table weighs 8 tons, so they designed a foundation which goes 500 mm under ground and is filled with steel reinforced concrete. I'll post about it when I get there in the build thread. They are also going to put a platform around the machine at this level for the operator. Maybe on my next visit it will be ready and I'll get photos of it. It is 10 hours drive from here.

164
Ok now. The design is approved so we go onto the drawing board. The linear table is the first priority.

First we design it to be made from cast iron, machine and fit linear guides to it. Calculated cost exceeds customer's budget. Switch over to plan B. Search for an old planar base and table. Found one in a junk yard in Lahore.

Scrap the vertical columns, gantry, drive motor, gears, rack and other fittings. Ship the base and table to Gujranwala at Mr. Iftikhar's workshop. He is a manufacturer of shears and press brakes (www.bncmachines.com) and helped me find this machine in Lahore.

Next step, find the ball screws.

165
Came up with this initial design. Add a linear table to the base, this will be our Y-axis. Lock the radial arm at 90 degrees to the table and use it as X-axis. Now we have a cartesian coordinate system instead of polar for the radial drill. Put ball screws and servo motors on X and Y axis. Another set on Z-axis too on the quill. Next step will be to calculate and design the linear table, ball screws, bearing blocks, servo motors, their mounting on the machine etc., etc., etc.


166
Ok. This is how it started.

Customer want to convert their radial drill into CNC. They need to drill holes in medium carbon steel upto 1600 mm dia and upto 150 mm thickness. That's roughly 2.5 tons or weight and they want repeatability of 0.05 mm between holes with that. They have a low budget for this so can't go for a new CNC machine. The drill they want to convert is an Italian machine. Manufacturer in Italy says that this can't be done and offers them their new CNC model (budget constraint!).

Here is the photo.


167
Wow..nice to see the machine here...

Forgot to tell that it's Khalid's machine. And I would have refused to start this one altogether if Khalid wasn't there. His help was a big contribution towards this project.

168
Thanks for the compliments Hood and Dan. Arduino is used just for Feed Rate Override and function buttons on the control panel. Don't need a commercial PLC for it.

I am planning to post a build log for this machine here. There are tons of pics and vids for this project on my PC. Let me sort and edit the photos and then I'll start from the beginning.

Zafar

169
These are the specs we achieved with this retrofit.

X-axis travel - 1515 mm
X-axis rapid speed - 20,000 mm/min (radial arm)
Y-axis travel - 2035 mm
Y-axis rapid speed - 7,500 mm/min (bed installed on machine base)
Z-axis travel - 400 mm
Z-axis rapid speed - 3,000 mm/min (quill)
Repeatability for X and Y axes - 0.05 mm
Maximum load tested on Y axis - 2,500 kg

Used Mach3 with smooth stepper ethernet and arduino modbus. AC servo motors on all three axes. 5.5 kW on Y-axis, 3 kW on x-axis, 1 kW on Z axis.

170
The CNC conversion project which was running for the last 8 months has finally finished. I am going to post photos and details about this project here. Here are the photos of the machine before and after the conversion. More photos to be posted later.

Zafar

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