How to log tapping torque? 2

[SharkMatt]

I work for a machining company. I am currently involved with a project to evaluate cutting fluids. This is in response to problems we have had with tapping. We would like to conduct a test of the lubricity of the various fluids by monitoring torque during tapping. I was hoping to use some sort of data logger to monitor torque during the tests. I understand that torque is generally monitored by watching the current drawn by the spindle motor. Then I would have to use a torque vs. current graph to relate the current back to torque. I have seen a few current dataloggers around that might be able to do this.

Do I need a datalogger for each phase? If so, how do I re-integrate these separate values for an overall torque value?

I also welcome any other comments on convenient ways to get this data.

 

[BobM3]

You might want to post this in the Electric Circuit engineering forum. There might not be many electrical guys in the Machining forum. Are you using a CNC machine? Many of them have torque (current) measurement available.

 

[SharkMatt]

Thanks BobM3. I will re-post.

I am using a Cinncinati 5-axis CNC machine. The problem is that I want to do a lot of test holes. The machine provides no option for logging data. Also, the indication is via a simulated meter on one of the screens in the control. The lag and the inaccuracy of visually recording the max value makes it seem pretty futile to glean useful information from the meter.

Why do I feel like I am re-inventing the wheel here? Hasn't anyone else needed to do this? We tried bringing in Emuge (tap manf.), but they refused to weigh-in on coolant issues.

 

[CoryPad]

MicroControls' Transient Recorder MC900 can do what you want. It was designed for fastener testing, but it can be adapted to your needs. You will need to get a rotary torque transducer from them in addition to the standard conditioner/recorder, and then attach the transducer to your CNC machine. Then, you can directly measure torque vs. time.

http://www.mcrts.com/Standard MC900.htm

Alternatively, you could get a rotary torque transducer (

http://www.rstechltd.com)

and then use simple recorder products from National Instruments or Vishay and have to do more data manipulation (transfer from recorder to computer, use Excel or something else to convert signal voltages to torque, etc.).

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[mk2000]

SharkMatt

Depending on you application and machine setup there may not ba linear relationship between 3 phase motor current and torque.

Make sure you understand how you machine is set up. To make sure you get a accurate answer use the direct measurement from a torque gauge or if possible stick a strain gauge some where on the machine or test specimen and measure the strain.