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Eccentric and Crank calculation

Eccentric and Crank calculation

Eccentric and Crank calculation

Hey all,
Our shop is trying to determine the tonnage force generated by an eccentric/crank in combination with a hydraulic motor.
Not being formally trained engineers, we are perhaps looking for a general tonnage chart or formula for a given stroke length and diameter that may not exist.
We are retrofitting a clicker press for cutting out fabric shapes and the original machine was equipped with an electric motor and gearbox to then run the eccentric and crank rod. This design is similar to the Di-Acro and Wysong press brake designs for sheet metal bending.
In our case, the press is rated for 40 Ton. We chose to change the power unit to a hydraulic pump and changed the transmission to a hydraulic wheel motor.The motor is then linked to the main shaft via heavy chain and sprockets.

The problem is that we cannot seem to predict the tonnage accurately enough to make the press cut the materials as before.

Any ideas out there on how to calculate the torque required by the motor and the resultant tonnage force generated by the eccentric/crank?


RE: Eccentric and Crank calculation

The problem with your request is that, theoretically (i.e., if all the structures were infinitely stiff, and did not stretch) the achievable loads are infinite. The load capability of a clicker press varies throughout its stroke. Adjusting the table height to the cutting stroke is important, as well as the hardness, flatness, and smoothness of the table. A small gouge in the table will prevent cutting in that spot.

RE: Eccentric and Crank calculation

It needs all the drawings from the original clicker press and someone needs to lay the mechanism configuration on a Computer. From that you can get crank angles at certain cutting positions and table position etc. Without that information you could spend a lot of time going round in circles.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

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