Hi,
I'm trying to design an 80KG lifting platform.
I thought of connecting the 4 corners of the platform to something like 4x 400mm Linear Shaft Rod (example) - which will provide stability. In addition to use 4x SFU1605 Antibacklash Ball Screw 400mm long (example) along with 4x Nema 23 12.6/cm 56mm (example) and 4x TB6600 (example).
When fully loaded (80KG), it needs to travel at a speed of ~1cm/sec or faster.
Total hight that the platform can raise is about 20-30cm.
The platform must remain leveled, I can tolerate 1mm of high differentiation between the 4 linear shafts; they must remained synced and leveled up to 1mm at all time (I can use end-stopper and reset the platform between each lift).
Please let me know what do you think (I need more/less motors or even switch to a pulley system and suggest other options)
Thanks!
If accuracy is not important, why use expensive ballscrews? Ballscrews have very little friction so if motor power fails the load will fall uncontrolled. Singly-threaded trapezoidal leadscrew ought to avoid that danger, although require more angular velocity for a given linear speed.
Some sort of leadscrew is probably good for this high load and low speed requirements.
Three rather than four leadscrews might be enough, saving cost.
Using one motor and a belt to distribute drive to each leadscrew is also a possibility, again saving hardware,
but the torque requirements might be an issue depending on the pitch of the leadscrew.
Simple DC gear motor with encoder is a possible alternative to stepper(s).
What happens if the 80kg decides to stand near one corner of the platform? Each actuator needs to be able to lift the entire 80kg all by itself.
Are the actuators supposed to be underneath the platform? Can it be suspended from cables above? Can it have tracks up the side and it rides up and down on those tracks?
What side loads are expected? Can the 80kg step off the platform while it's fully raised? The action of stepping off or on will push the platform sideways with significant force.
Depending on the underneath/above answer, I would consider using a single point hoist above or modify a scissor-lift table like you sometimes see used for lifting car transmissions or even entire cars. Converting manual-hydraulic one to automatic-electric should not be too hard if you can find a linear actuator with the required force and travel.
MarkT:
If accuracy is not important, why use expensive ballscrews? Ballscrews have very little friction so if motor power fails the load will fall uncontrolled. Singly-threaded trapezoidal leadscrew ought to avoid that danger, although require more angular velocity for a given linear speed.
Some sort of leadscrew is probably good for this high load and low speed requirements.
Three rather than four leadscrews might be enough, saving cost.
I just updated the post. I can tolerate 1mm of inaccuracy.
regarding the cost, its about 60% (a complete z access set) - but it might require a faster/stronger motor, which will cost as much. am I right?
MarkT:
Using one motor and a belt to distribute drive to each leadscrew is also a possibility, again saving hardware,
but the torque requirements might be an issue depending on the pitch of the leadscrew.
Simple DC gear motor with encoder is a possible alternative to stepper(s).
MorganS:
What happens if the 80kg decides to stand near one corner of the platform? Each actuator needs to be able to lift the entire 80kg all by itself.
I actually aimed to lift around 40kg, but I just wanted to be safe. In addition the weight is always spread across 2 or more corners.
MorganS:
Are the actuators supposed to be underneath the platform? Can it be suspended from cables above?
I'm still not sure if I will need to push up like a loading platform or pull down like a press.
Assuming that I will continue as planned (platform, push up), I will be able to place the actuator underneath my load or use a pulley and vise versa.
MorganS:
Can it have tracks up the side and it rides up and down on those tracks?
I think that it will be a great idea to have tracks up its sides.
MorganS:
What side loads are expected? Can the 80kg step off the platform while it's fully raised? The action of stepping off or on will push the platform sideways with significant force.
I would like to use rails/tracks to avoid those issues
MorganS:
Depending on the underneath/above answer, I would consider using a single point hoist above or modify a scissor-lift table like you sometimes see used for lifting car transmissions or even entire cars. Converting manual-hydraulic one to automatic-electric should not be too hard if you can find a linear actuator with the required force and travel.
I would like to build everything at home rather than buy something ready like a scissor-lift table.