×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Calculation of force for shearing with rotating blades

Calculation of force for shearing with rotating blades

Calculation of force for shearing with rotating blades

(OP)
Hi,
can anyone help me with defining the force that is needed for shearing of sheet steel (st.37) with 2 rotating blades? The principle can be seen on this video: https://www.youtube.com/watch?v=da99re5O0Rc.

I need to define the force for penetration (blades going down) and for rotation of the two blades (see image).

Thank you,

P

RE: Calculation of force for shearing with rotating blades

(OP)
Ok, I see noone is answering.

Let's say we got a 4 mm thick sheet and we want to cut out a diameter of 800mm. The rolling knife has a diameter of 110 mm.

I only need the formulae for the forces acting on the knife...please.

Thank you,

RE: Calculation of force for shearing with rotating blades

To me it's a wedge principle to divide steel sheet without metal removal.
So if you transfer the formulas on this page:
http://en.wikipedia.org/wiki/Wedge_%28mechanical_d...
to the circular knife motion, that will be a good starting point.
Guess it will require a lot of force.

RE: Calculation of force for shearing with rotating blades

(OP)
Thank you jlnsol, I will check it up.

P

RE: Calculation of force for shearing with rotating blades

Looks more like a shearing action to me - like tin snips or a guillotine. The tricky bit will be determining the area of the cross section being sheared. This will depend on the depth setting of the knife.

eg if the section being sheared is 20mm long, the area will be 20 x 4 = 80 sq mm. Force will be area times average shear stress across the section (somewhere between 50% and 100% of ultimate shear stress for the material).

USS = about 0.75 x UTS for steels. So a 400 MPa steel would have USS of 300 MPa and the force in the example would be
300 x 80 = 24,000 N per wheel. This is the normal force - the vertical (press force) and horizontal (spindle torque) force components will depend on the angle of the Normal force vector (a line through the shering section and the axis of the cutting wheel)

je suis charlie

RE: Calculation of force for shearing with rotating blades

If you have a Machinery's Handbook, look up the section on the shearing process.

Ted

RE: Calculation of force for shearing with rotating blades

(OP)
Hi, hydtools. Which version of MH do you have. I have the 27th and 28th but I can't find the shearing process.

RE: Calculation of force for shearing with rotating blades

A condition for shearing is a counterdisc underneath the plate being cut. (Plus narrow tolerances between top and bottom disc. In the video it doesn't look like that.

RE: Calculation of force for shearing with rotating blades

(OP)
Hmm, so you say this is a cutting process and not shearing?

RE: Calculation of force for shearing with rotating blades

Indeed.

RE: Calculation of force for shearing with rotating blades

My eyesight isn't all that good but I am pretty sure there is a counterbore in the reaction bed. So yes - shearing.

je suis charlie

RE: Calculation of force for shearing with rotating blades

gruntguru, you're right, shearing, I looked once more to the video and yes there is a table with counterbore underneath the plate.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources