B Torque Calculation - Not a basic application

  • Thread starter Thread starter TeeBeeCee
  • Start date Start date
Click For Summary
The discussion revolves around calculating the torque delivered by a hydraulic machine used for tightening bolts and nuts. The hydraulic ram, with a 4-inch diameter piston generating 100 PSI, applies force to a cog, and the torque is influenced by the angle at which the ram engages the cog. The torque formula T = F x r x sin(theta) is highlighted, emphasizing that both the radius (r) and angle (theta) change during operation, affecting the torque output. Accurate measurements of the stroke length and angles are crucial for precise torque calculations. The goal is to tighten bolts to specific torque specifications by adjusting hydraulic pressure accordingly.
  • #31
TeeBeeCee said:
Have no idea why the last pressure entry only increased by 15 when all the others were 25.
I'd guess the maximum operating pressure for the equipment is 315 bar, so the final value in the table is 315 bar rather than 325 bar.
 
Physics news on Phys.org
  • #32
TeeBeeCee said:
If so, the point I made was that I have no idea if the data is correct and wanted to verify.
Thats fine, but you are going to need precise/accurate measurements of the variables before you can do that. We have to be critical of the model that comes from pure mathematics over what was experimentally measured by the company which designs and manufactures it. There may be "hidden variables" that are difficult to pin down theoretically that would show up experimentally. It's not so easy. Do you suspect a miscalibration, why?
 
  • #33
erobz said:
Thats fine, but you are going to need precise/accurate measurements of the variables before you can do that. We have to be critical of the model that comes from pure mathematics over what was experimentally measured by the company which designs and manufactures it. There may be "hidden variables" that are difficult to pin down theoretically that would show up experimentally. It's not so easy. Do you suspect a miscalibration, why?
I don’t suspect a mis-calibration. It’s just that torque specs are important. A loose bolt or nut can cause severe equipment damage. Just trying to make sure I limit my liability.
 
  • #34
Steve4Physics said:
I'd guess the maximum operating pressure for the equipment is 315 bar, so the final value in the table is 315 bar rather than 325 bar.
Good guess. I just checked and the maximum pressure of the hydraulic pump is 300 bar.
 
  • #35
Regarding that table entry for 300 Bar.
It appears to be a transcription error by whoever supplied the table. The rest of the table is completly linear.

As for the 300 Bar entry, if the "9" is changed to "0", then all the digits match as 3 times the 100 Bar value and 6 times the 50 Bar value.

Except for the last digit, it also matchs as 12 times the 25 Bar value which is likely a round-off error in the 25 Bar value.
 
Reply
  • Like
Likes SammyS and Lnewqban
  • #36
Tom.G said:
Regarding that table entry for 300 Bar.
It appears to be a transcription error by whoever supplied the table. The rest of the table is completly linear.
The torque at 300 bar is given as 59530.41 Nm. It appears that the '9' should be a '0', i.e. the value should be 50530.41 Nm.

This puts the 300 bar point exactly on the straight line formed by the other points.

Incidentally (I don't think anyone has said it yet) giving the torque values to 7 significant figures leaves something to be desired!.
 
  • #37
Does anyone else suspect the table not to be actual measured data. It's too perfect (other than the expected typo)?
 
Last edited:
  • #38
erobz said:
Does anyone else suspect the table not to be actual measured data. It's too perfect (other than the expected typo)?
Yes. Almost certainly.

Maybe the values are calculated from the accurately known dimensions (which was what the OP originally wanted to do).

Or maybe the values are based on actual measurements and the best-fit straight line was found. Then the table could be constructed using the gradient of the best-fit line.