Polar Mohr Eltromat 72 Knife not coming down

Knife some times come down and some times not work
After switched off and wait for a while to cool down, again will work. For this we have replaced carbon brushes.
What could be the reason?

 

Hello. I don't know this particular guillotine, but they normally have a sensor or actuator that is placed in the cam of the knife. They start failing eventually and then they don't work anymore, which gives you time to buy a new spare part. Sorry if the information is too vague, but I am not a technician, just a maintenance engineer. Regards

 

Hi sir:

1) immediately when you turn ON the machine small relais d230 in the electronic box will be closed.or pull in.+d230A+D230B
if this condition is o.k , go to see the steps # 2 normally this paper cutter has 1 electronic box # 7SB

2) When you press the cut buttom , see if the small relais, d1 is pull in ??? , IF NOT, go to safety bolt rear of the machine, and adjust the limit switch b.SB(d40.1 +d40.7) must be closed use the DMM in continuity and adjust the l.switch, clean it, and tight very well the cables, and see if the contacts are bad, or defective, and if is necessary replace it the limit switch, if are o.k the l. switch see if they are +24Vdc in d40.7?

3) if there are not , go to the Cut buttoms, open and see if there are dirty, loose wires, defective, and replace if necessary.

4) if everything is o.k the small relais D1, will be pull in, test very well this smal relais, and see if the small contacts are o.k or broken, and repair or replace it.

5) if the small relais d1, is o.k will work too the small relais d2+d3, this will attract the Safety bolt with +42Vdc, see if they are by measuring D 40.3 +d40.6, if there are LUBE the magnet SAFETY BOLT, With graphite.

6) immediately when you press the cut buttoms, the smal relais d 70a must be close to activate, the Inverter, the magnet solenoid M27 for clamping, and closing the Relais:d21+d21a+d21b, for to activate the electromagnetic clutch M33 , WITH +42Vdc.

In every steps, please, tight very well the connectors, clean it, look for broken wires, loose wires, bad contacts, and defective relais, or dirty, or broken contacts.

Let me know, sincerely

 

Dear Sir,
Every press of cut button by hand, Voltage have reaches to carbon brush on the flywheel is Aprox 38v instead of 42V. ( attached video are while holding cut buttons, while knife stop working)

Even if 38V, Around 40cuts possible with knife, then knife stops working, that time- while pressing cut buttons by hand, getting 38 V in the flywheel. But clutch not holding

After switched off a while for cool, then cut is possible.

Clutch could be a problem? Or voltage drops(38v)?
Please suggest..other possibilities too

 

Hi, You must have to adjust the primary input if main transformer.
In according with voltage that y have, 380Vac, or 220Vac, or 409Vac 3 phases.

2) increase the voltage for clutch, for 38 , to 42- 48Vdc Non Regulated power supply.

3) However is possible, (and 100% ) sure, the coil of clutch is Reheating!!, Not burning, you must to repair the winding, to due the varnish cover winding.

Let me know ASAP

Blessings

 

Further to your advice, checked coil resistance from slip ring,
knife working time resistance is 32 Ω and when the knife stop due to heat- at the time resistance is 26Ω

So, can we confirm to do coil winding ?

 

That is 1) indicative from low voltage 38 Vdc, to the clutch, as I did explain you before , you must have 42-48Vdc. !!

2) Reheating winding of clutch, repair or replace it

Blessings

 

Dear Sir,
Me rewinded coil of clutch and fixed on the machine, problem still exist.

Power details: we have 3phase 220v converting to 380v by transformer( 384v is getting).
From step down transformer 48v AC to bridge rectifier, it’s out put DC 48V, positive wire connected to relay and negative wire connected with many other wires( as common wire)

I mean to say that, we have getting 48vDC upto relay input, but while press the cut buttons, relay holds then clutch coil energized and voltages decreases to 38vDC..( voltage drop or it’s normal?) that’s way 38VDC reads on carbon brushes.

If it is not normal, any suggestions?

Another observation is, while holding the cut buttons and try to push the clutch plate towards the clutch coil by long screw driver, clutch holds and every time knifes comes down this way. Could be a spring issue or voltage issue?
Photo attached.

 

Hi sir, my apologize for the delay, to reply you, but It is a hard time for me, after surgery of tumor cancer of my wife , now with Chemical Therapy with; Circunstances +Time+Money+Hospital etc.

If the converter that you have is from 220Vca to 380 Vca, adjust the Primary TAP in the transforme to the next Tap Higher.!!

Drop Voltage in the secondary transformer will be Minimum, 1)please measure in the connector d8.2+d8.3 = 50VcaAprox , this voltage Feed to the Input to bridge rectifier in the

2)point; 4.5+6 vs 4.1+2 Ground= 50Vca !!!

3)24.34 = +42vDC

4) 24.42 OR d2.1 = +42Vdc, if this point the Voltage is NOT +42Vdc, please review the contacts from Relays D21a+b, clean very well, and close very the N.C contacts, in order to pass very well the Voltaje to the coil of Clutch.

If everything is well with the Electrical/Electronic Power supply.

Go to the Clutch;

Adjust the Inner Gap between drive wheel and brake disk when is engaged ; must be 0.2-0.4 mms .!!!!
Clean very the disk, exchange the bearing, Lube.

Good luck.

 

It means the air gap between the clutch and disk is too far or wide. You have to decrease the air gap. The electro magnet has a hard time absorbing the disc because of the huge gap.