Torque Calculation - Not a basic application

  • Context: High School 
  • Thread starter Thread starter TeeBeeCee
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Discussion Overview

The discussion revolves around calculating the torque delivered by a hydraulic machine used for tightening bolts and nuts. Participants explore the mechanics of the hydraulic ram, the cog's role, and the impact of various angles and forces on torque. The conversation includes practical applications and theoretical considerations, with a focus on real-world physics rather than purely academic perspectives.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants inquire about the effect of the angle of the ram engaging with the cog on the torque delivered.
  • There is a suggestion that the torque on the nut or bolt increases with the distance between the shaft and the center line of the cylinder.
  • Participants discuss the need for additional information, such as the maximum stroke length of the ram and the angle changes during operation, to calculate torque accurately.
  • One participant emphasizes that the required torque is reached at the angle where the bolt or nut assembly achieves maximum clamping force, indicating variability in torque values based on angle.
  • There is a discussion about the relationship between pressure, force, and torque, with some confusion regarding the distinction between pound force and foot-pounds of torque.
  • Participants mention the importance of understanding the mechanical setup, including the role of the gear and its teeth, and request visual aids to clarify the mechanism.
  • One participant proposes using trigonometry and the Law of Cosines to relate the variables involved in the torque calculation.

Areas of Agreement / Disagreement

Participants express differing views on the impact of various factors on torque calculation, such as the angle of engagement and the role of the cog. There is no consensus on a definitive method or formula for calculating torque in this specific application, indicating ongoing debate and exploration of the topic.

Contextual Notes

Participants note the complexity of the problem, including the need for precise measurements and the influence of multiple variables, such as pressure, angle, and mechanical configuration. Some assumptions about the system's behavior remain unaddressed, and the mathematical steps required for a complete solution are not fully resolved.

  • #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.
 
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  • #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.
 
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  • #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!.
 
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  • #37
Does anyone else suspect the table not to be actual measured data. It's too perfect (other than the expected typo)?
 
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  • #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.
 
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