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  1. #21
    Join Date
    Nov 2019
    Posts
    16

    Re: CNC Tube Bender

    After a lot of research, I found this actuator reference from Nabtesco:
    https://precision.nabtesco.com/en/products/detail/AF-N

    So it's a geared servo motor, they even mention the Tube bender use case in the doc so I guess it should work.
    So I asked a quotation for the following 2 models:
    - AF042N126 (A6_1kW) with a rated torque of 412N and speed of 15rpm
    - AF080N129 (A6_2kW) with a rated torque of 784N and speed of 15rpm
    The problem is I don't know yet the price but I already know that I will have to wait 1 or 2 months as the local distributor doesn't have it in stock.

    So I would be very interested to have a plan B, like maybe with a gear and servo separated.
    Like a Mitsubishi one for the Servomotor as it seems easier to find where I am, but then come the gearbox where I don't know much about it...
    I guess there is the formula to calculated the rated torque of a servo + gear reducer?
    Or if anyone know some suitable references, I would be very interested.

    Thank you very much

  2. #22
    Join Date
    Dec 2013
    Posts
    5717

    Re: CNC Tube Bender

    Maybe this one in a 160:1 ratio. Could be used with a 1 - 2 KW servo motor and give the needed torque. Harmonic gear reducer / hollow-shaft / high-precision / electrical for servo motors - RITM IndustryRITM Industry
    Jim Dawson
    Sandy, Oregon, USA

  3. #23

    Re: CNC Tube Bender

    You should make sure that you are sitting down when you receive the quote for a harmonic drive of the correct size. However, you can buy pre-owned examples from ebay dealers in South Korea and China. The prices are still significant but still quite a bit less than a new one.

    Looks as if a 45 or 50 size drive would be required. https://www.harmonicdrive.net/produc...-units/shg-2uh

    Most of these cnc benders use internal mandrels to stop the tube collapsing. Basing it on a basic Baileigh(?) machine doesn't sound like the greatest idea.

  4. #24
    Join Date
    Nov 2019
    Posts
    16

    Re: CNC Tube Bender

    Quote Originally Posted by Muzzer View Post
    You should make sure that you are sitting down when you receive the quote for a harmonic drive of the correct size. However, you can buy pre-owned examples from ebay dealers in South Korea and China. The prices are still significant but still quite a bit less than a new one.

    Looks as if a 45 or 50 size drive would be required. https://www.harmonicdrive.net/produc...-units/shg-2uh

    Most of these cnc benders use internal mandrels to stop the tube collapsing. Basing it on a basic Baileigh(?) machine doesn't sound like the greatest idea.
    at the begining I wanted to reuse the dies from my manual bender but no way it's not gonna be possible, so it's ok I will draw it and there is a workshop near my house that can machine it.

    What I'm designing now is a CNC mandrel bender,
    I already solved the problem of feeding part (Z-axis) that is going to be ensured by a rack and pinion and 2 guide way from Hiwin, and the rotation of the tube, it's basically a rotary chuck that have 2 servos, one to control the opening and closing of the chuck and one to control the rotation of the tube.

    now I'm starting the bending part, the bending will be a bending arm bolted on the geared servo motor, and the clamping system will be on this arm made of a linear actuator using a servo that will push the clamping die.
    Then will come the controlling part and it's gonna use some Arduino based PLC.
    So for now I think the most suitable i found is this geared servo from Nabtesco but as i was saying earlier I gonna have to wait 1 or 2 months once it will be ordered and i still didn't receive the price:
    https://precision.nabtesco.com/en/products/detail/AF-N
    So I'm looking for alternative

    I also saw this:
    http://www.apexdyna.co.th/index.php?...e&Id=539968170
    but I'm not sure if it suitable, I'm trying to look at what is available here in Thailand, so there is principally Japanese, Taiwanese brand but I really have no clue about gears...

  5. #25
    Join Date
    Nov 2019
    Posts
    16

    Re: CNC Tube Bender

    Quote Originally Posted by Muzzer View Post
    You should make sure that you are sitting down when you receive the quote for a harmonic drive of the correct size. However, you can buy pre-owned examples from ebay dealers in South Korea and China. The prices are still significant but still quite a bit less than a new one.
    How much should I expect for such gear?
    I'm expecting to pay around 1500$ for the bending servo and gear as it's the biggest one and it's about few hundreds dollars for the other axis servos, it's just a guess to be honest.

    I'm close? or very far?
    Last edited by garthos; 07-01-2020 at 03:36 PM.

  6. #26
    Join Date
    Oct 2022
    Posts
    3

    Re: CNC Tube Bender

    Did this CNC Bender ever happen?

  7. #27
    Join Date
    Jan 2013
    Posts
    474
    Quote Originally Posted by Tinine View Post
    Did this CNC Bender ever happen?
    Doubt it
    You need hydraulics to generate the bending moment needed for pipe, using proportional control valves and encoders for feedback.
    Not servo motors.

  8. #28
    Join Date
    Dec 2003
    Posts
    24216

    Re: CNC Tube Bender

    Quote Originally Posted by servtech View Post
    Doubt it
    You need hydraulics to generate the bending moment needed for pipe, using proportional control valves and encoders for feedback.
    Not servo motors.
    My experience also, per post #10.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  9. #29
    Join Date
    Oct 2022
    Posts
    3

    Re: CNC Tube Bender

    United States Patent 5,862,697
    Electric CNC Tube Bender. That's my name on it.

    All the big-name CNC bender manufacturers now make 100% electric CNC benders. I started the whole thing but was never really a fan. Much prefer the hybrid approach.

    There has been mention of proportional valves; not strictly necessary. Take a bang-bang (directional valve) with DC coils and PWM the coils. Horrendous deadband/hysteresis but if one has control of the PID, this is easily compensated for. When forming a tube, the bend-arm only needs to hit a target.

    Distance Between Bends (DBB) is the Y axis
    Plane Of Bend (POB) is the B axis
    Degree OF Bend (DOB) is the C axis

    And this is how a CNC tube bender is programmed - Lengths, Rotations, Angles. No G-Code involved.

    It's a real shame that nothing came of this project

    Regards,

    Craig

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