Frequent start/stop, conveyor.

Elcan

Lifetime Supporting Member
E
Join Date
Apr 2008
Location
NC
Posts
935
Hi all,
I'm dealing with an application that, even though it is not sophisticated, is new for me. Excuse my ignorance!!!
I have an exiting conveyor that has a 1 hp DC motor. The new use for this conveyor is to be starting and stopping very frequently. It can be stopped as short as 2 seconds and then running as short as 1 second. The motor will be operated by a drive to control speed.
Is a DC motor suitable for this frequent start/stop application? Otherwise, what would be the best approach?

Thank you!
 
What type of drive is it, exactly ?

DC motors generally require a "four quadrant" drive in order to use dynamic braking. A small motor doing fast cycling will very likely need an external braking resistor to bleed off that energy.
 
Ken Roach said:
What type of drive is it, exactly ?

DC motors generally require a "four quadrant" drive in order to use dynamic braking. A small motor doing fast cycling will very likely need an external braking resistor to bleed off that energy.
Click to expand...

I need to buy a drive yet. I'm open to suggestions.
 
Gene Bond said:
https://www.kbelectronics.com/

These days, the market is somewhat limited. I'd go ahead an just use a regen drive, rather than deal with the 'cobbled up' relay brake/reversing circuits that look way to old fashioned to me.

Look at: https://www.kbelectronics.com/kbsearch/descriptions/kbcc_r.htm
Versus: https://www.kbelectronics.com/kbsearch/descriptions/popup_kbmg_212d.htm

My 2 cents worth...
Click to expand...
Thank you for the recommendation. Is there a NEMA 4 version for those chassis?
 
I've used the KBMG a lot over the years with no problems - can't go wrong there!
If you need it enclosed - look at the KBRC

Dart is also another brand that may have what you need
 
I suspect you will also need to be concerned about the amount of heat that the motor will generate with all the starting and stopping. It will probably at least need a constant running cooling fan.
 
Elcan said:
Hi all,
I'm dealing with an application that, even though it is not sophisticated, is new for me. Excuse my ignorance!!!
I have an exiting conveyor that has a 1 hp DC motor. The new use for this conveyor is to be starting and stopping very frequently. It can be stopped as short as 2 seconds and then running as short as 1 second. The motor will be operated by a drive to control speed.
Is a DC motor suitable for this frequent start/stop application? Otherwise, what would be the best approach?

Thank you!
Click to expand...

I've wondered, in recent years, why people don't consider Clutch/Brake setups. Yes, its a point of failure, and a wear point, but.....the drive can just stay running, and you then engage or disengage the C/B, and don't have to deal with the other electronic issues. Old School - YES, but, sometimes the old school still works.
 
Interesting idea with the clutch/brake. We have a number of them where I work and, yes, they work well.

The one problem I see is the cycle time: 1 to 2 seconds (stop and start). My guess is that the wear pad would have to be replaced a lot.
 
Years ago I worked on a conveyor that had to start and stop very quickly and with a very short cycle time. In fact they had to index the conveyor to limit switch.
They used a vacuum brake clutch it was very fast and reliable.
I don't know where they got it but I am sure that an internet search will pop up something
 
I have a similar application; except power is much higher. Rockwell Kenitx 5500 system; 440V 23A.


It will depend on the acceleration and deceleration rates you need; but this type of application is exactly what servo motors are great at.


Controlled speed, acceleration and jerk rate. Also control for slop (backlash) in the mechanical components with an appropriately placed encoder. Precision positioning.



My application

average run time ~2.5s

average stop time ~0.8s

max speed 920mm/s

max accel rate 5000mm/s^2
max jerk is a calculated value from the inertia measurements during setup.
 
PapaSmiff said:
Interesting idea with the clutch/brake. We have a number of them where I work and, yes, they work well.

The one problem I see is the cycle time: 1 to 2 seconds (stop and start). My guess is that the wear pad would have to be replaced a lot.
Click to expand...

https://www.forcecontrol.com/

Cycle times and wear are not an issue, or at least not much of one. The oil shear (much like a motorcycle clutch) means the transmission fluid wears, not the faces of the plates. Check out some of their videos and case studies.

I've used drives and clutch/brakes. Just depends on what the customer is comfortable with.
 
GaryS said:
Years ago I worked on a conveyor that had to start and stop very quickly and with a very short cycle time. In fact they had to index the conveyor to limit switch.
They used a vacuum brake clutch it was very fast and reliable.
I don't know where they got it but I am sure that an internet search will pop up something
Click to expand...
I tried a Google search and it returns mostly automotive applications...
 
Regardless of the solution, you should consider winding RTDs or other motor temperature monitoring system. The frequent starts of the conveyor will draw high current, even with a mechanical clutch, because you have to accelerate the load. The drive, if used, should have temperature monitoring.

I wouldn't worry about the wear on a clutch/brake system. "Back in the day" before drives and soft starts were available this was the standard method of performing tasks like yours.

https://www.ask.com/web?q=clutch+brake+industrial+applications&o=0&qo=homepageSearchBox
 

Similar Topics

B
The frequent loss of Powerflex 4 and 40's throughout our plant.
Happy New Year , We have a number of Powerflex 4's and 40's throughout our plant. We have had a outrageous number of these drives fail the...
2
Replies
18
Views
6,126
HJTRBO
HJTRBO
T
VFD - Frequent Frequency changes
I've got a question, maybe an issue, but more just curiosity. I have an air compressor, 100HP, that runs with VFD contorls. It is the only one...
2 3
Replies
35
Views
9,632
DickDV
D
G
OT: frequent motor reversal questions
Hi, I have a 1hp 3 phase 220 volt motor on a fixture with a very light load that is required to reverse very frequently. It is required to run...
2
Replies
20
Views
5,977
danatomega
D
C
Understanding LL frequent forms
I am updating a machine first commissioned in 1998 with a FANUC 90/30 plc From hours of study, it appears that the original logic documentation...
2
Replies
25
Views
4,688
CalG
C
C
Frequent Motor Starting
I'm looking at a project where a cleated conveyor (chains on either side connected by a metal cleat with product between the chains being pushed...
2
Replies
16
Views
7,094
iant
iant
Back
Top Bottom