Digi DC-300 Manuel d'instructions télécharger pdf (Page 12)

Digitronic Digital Cam Switch Unit

Automationsanlagen GmbH CamCon DC300

2.1.2. Speed Compensation using off-centre pressure, e.g. brake functions

The Speed Compensation of the CamCon Cam switch unit works using a linear function. If, for

example, the speed doubles, then the shift of the compensated cam changes and also moves forward

by twice the amount. If the ram on an eccentric press should be brought to a standstill at the exact

upper stop point, the brake action of the press under different speeds results in a quadratic function.

The Speed Compensation can therefore only find an approximation of the exact switch point for the

stopping of the press by adjusting the line of the cam lines to the brake curves in the working range of

the press.

Note: See also the next chapter "2.1.3. Not linear Speed

Compensation (NLT)".

U/min

Verlauf Nocke 1 Nocke 2

In the graphic on the right the curved line represents the

brake point of the ram in relation to the speed.

For the calculation of the parameters to be programmed

please proceed as follows:

- Define the working range (e.g. 20-50 rpm) and determine

two measuring points which have to be specified in the

working process (e.g. 30 and 40 rpm).

- Now let the machine run at 30 rpm and program or

optimise a cam without Speed Compensation so that, at

switch-OFF, the ram comes to a halt in top stop. Note the

switch-ON point of the cam (e.g. 340°).

- Now let the maching work with 40 rpm and program or

optimise one cam without Speed Compensation so that,

at switch-OFF, the ram comes to a halt in top stop. Once

again, note the switch-On point of the cam. (e.g. 332°).

- Now calculate the delay time, taking into account the

distance and speed difference, using this formula:

Delay time ( in sec. ) =

∆ way (in °) * 60 (sec./min.)

∆ Speed (in rpm.) * 360 (°/turn)

340-332 * 60

40-30 * 360

= 0.133 sec.

- The calculated delay time is now entered into the cam switch unit.

- Since the switch-OFF point has shifted through the entered Speed Compensation, the previously

programmed cam must be changed first. For the calculation of the exact switch-ON position, the

difference to the speed 0 rpm (here 30 rpm) must be added to the first measured switch-ON point

(first measuring point here 340°) The difference is calculated with the following formula:

∆ way (in °) =

delay time ( in sec. ) * ∆ Speed (in rpm.) * 360 (°/turn)

60 (sec./min.)

0.133 * 30 * 360

= 23.94°

- The switch-ON point of the cam has now shifted from 340° by approx. 24° to 364°.

As a result a cam with a switch-ON point of 4° and a speed compensation of 0.133 sec has been

calculated. This is entered in the cam switch unit as switch-OFF cam of the press.

Note: If the degree of accuracy is no longer sufficient when switch-OFF is done with one cam, two

or several outputs can be switched in parallel and the cam of those is then adjusted to the

required working range. For the calculation of two switch-OFF cams divide the working

range in 5 parts with 4 measuring points and then calculate the delay time value and the

cam value with the same formula as described above. For the calculation of the first cam,

use the measuring points 1 + 2 and for the calculation of the second cam use the

measuring point 3 + 4.

Through this association of the linear cam functions to the brake functions it is now possible to switch

OFF the cam via the entire working range of the press in the top stop.

Version: 25.02.2014 Page: 12

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Digi DC-300 Manuel d'instructions Page 12

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