Tool Load Monitoring During Rigid Tapping

[abhthree]

Hello,

We have a Doosan MV5025 with a Fanuc 32i-Model A control. We purchased the machine in June of 2010. When I bought the machine I bought the tool load monitoring option. We use the machine to drive a large tap in production. The blanks are loaded by a little robot, and then the hole is tapped. Our goal was to monitor our taps and be able to switch taps out once the load was too high, in order to prevent breaking fixtures.

After months of headaches it was deemed that the tool monitoring does not work while in rigid tapping. We were credited for the option, but I was left without the ability to monitor the spindle load during tapping.

Does anyone know of a work around for this problem? I am able to see spindle load on an analog gauge and a digital read-out in the machine. Is there a way to capture this variable through a custom macro and allow me to monitor the torque on the spindle? Any help would be appreciated.

[FANUCCNC]

Looking at the spindle load monitor, is there a significant difference between running the part program with no tool and the rigid tapping tool?

Is the load when rigid tapping consistently above the no tool load?

Which option did you purchase, that did not appear to work?

If there is a true difference between the load when tapping and when the tool breaks there may be a solution to detect.

[keebler303]

Originally Posted by FANUCCNC Looking at the spindle load monitor, is there a significant difference between running the part program with no tool and the rigid tapping tool? Is the load when rigid tapping consistently above the no tool load? Which option did you purchase, that did not appear to work? If there is a true difference between the load when tapping and when the tool breaks there may be a solution to detect.

I think he wants to look at when the load is increasing to change the tool BEFORE the tap breaks. In that case, you can run one until it breaks and then you will know what the spindle load was when it broke and so in the future you will change tools some amount of cycles before you reach the "breakage load". I would think you could work something out to monitor it but you could probably get a good idea of how many holes you can tap before changing and then just change the tool after X number of holes.

Matt

[FANUCCNC]

The challenge is can you really tell the difference between a broken tool, no tool and a good tool. A lot of solutions fail in certain applications because the torque variability cutting with a good tool and the torque variability with no or a broken tool overlap. So either you miss broken tools or you sometimes trip good tools. If there is good separation, there may be a few solutions available.

If really knows how many cycles the tool can take, either in number of operations or cutting time, then the tool management feature could help.

[Geof]

When the spindle is tapping the acceleration torque is greater than the tapping torque so how do you distinguish between the two?

[FANUCCNC]

I assume that the acceleration of the spindle takes place before the tap enters the work piece. That is the S command is given and the spindle can come up to speed in a prior block. If that is the case, any monitor can be activated only during the Z feed blocks.

Also we have to define the goal. A tool management approach with conservative values should ensure the tool doesn't break. A post process gage on the tap could detect if the tap broke to prevent further problems.

[keebler303]

The tap also has to decelerate at the bottom, which could be a larger load than tapping depending on how quickly you need/want to stop it. If you could tell driving load from braking load then it would not be a problem. An analog current meter would not know if the motor was speeding up or slowing down so a rapid decelaration might look like a high tapping load. On the way out its not an issue because the tap is probably not going to break on the way out.