How to manufacture / bend small copper u-channel // Tape Cover - Page 2
Close
Login to Your Account
Page 2 of 2 FirstFirst 12
Results 21 to 34 of 34
  1. #21
    Join Date
    Oct 2017
    Country
    UNITED STATES
    State/Province
    California
    Posts
    1,451
    Post Thanks / Like
    Likes (Given)
    480
    Likes (Received)
    484

    Default

    Just mill the part out of billet if you just need one, instead of building an entire press.

    I disagree with the people who say you just need a simple punch and v-die in a shop press. Dimensions will be terrible without a back gauge, and the flaring on the part will be awful due to the proximity of the contour and bends.

    I would form this blank with a set of wiper dies. A conventional V die will badly indent the material if the V-die is small enough to actually bend the entire flange. Then I would use a radius punch on a urethane die to form the curved portion.

    I can't tell for sure what your minimum flange widths are and at that thickness of copper you can probably use a 1/4" urethane V-die which can be ordered in small quantities cheaply if you can avoid having cutouts within about 0.15" from the bend centerline.

    A bottoming die is possible but you will need a very large shoulder radius to deal with the transition from the bent/ unbent portions of the contour and to avoid marking. A v opening wider than significant portions of the flange can cause parts to occasionall "pop" to a different bend position. I've dealt with this on a production run and it was absolutely awful.

    I would use a rolla V die such as an RVT100-1, and a deep gooseneck punch with 0 punch radius. I don't have the part number for the punch because I'm away from the shop on fire evacuation.

  2. #22
    Join Date
    Nov 2013
    Location
    Eastern Massachusetts, USA
    Posts
    7,819
    Post Thanks / Like
    Likes (Given)
    6493
    Likes (Received)
    6918

    Default

    Quote Originally Posted by Strostkovy View Post
    Just mill the part out of billet if you just need one, instead of building an entire press.

    I disagree with the people who say you just need a simple punch and v-die in a shop press. Dimensions will be terrible without a back gauge, and the flaring on the part will be awful due to the proximity of the contour and bends.

    I would form this blank with a set of wiper dies. A conventional V die will badly indent the material if the V-die is small enough to actually bend the entire flange. Then I would use a radius punch on a urethane die to form the curved portion.

    I can't tell for sure what your minimum flange widths are and at that thickness of copper you can probably use a 1/4" urethane V-die which can be ordered in small quantities cheaply if you can avoid having cutouts within about 0.15" from the bend centerline.

    A bottoming die is possible but you will need a very large shoulder radius to deal with the transition from the bent/ unbent portions of the contour and to avoid marking. A v opening wider than significant portions of the flange can cause parts to occasionall "pop" to a different bend position. I've dealt with this on a production run and it was absolutely awful.

    I would use a rolla V die such as an RVT100-1, and a deep gooseneck punch with 0 punch radius. I don't have the part number for the punch because I'm away from the shop on fire evacuation.
    I did not say V die. What I was suggesting was modifying flat punch and dies used as options on press brakes for tube flattening, etc.

    A lot of shops have press brakes but not many have stamping presses and die set holders.

  3. #23
    Join Date
    Apr 2007
    Country
    UNITED STATES
    State/Province
    South Carolina
    Posts
    79
    Post Thanks / Like
    Likes (Given)
    15
    Likes (Received)
    10

    Default

    #1 you need to find a shop that will laser cut the blank, if only for developing for the bends. I think you do need tool steel because it is hard and you don't need two soft metals rubbing together, and once you have it right, you don't want the die to score, pick up or introduce lines into the part. A U die with a cushioned
    pad to keep the bottom flat, or add set to kill springback plus eject the part. You will want some sort of nest as well that you can adjust. I haven't read far enough to see how many parts you are looking to make. this gets expensive for limited runs unless you are recreating a high value oem part that is unobtainable and have some one willing to pay good money for tham.

  4. #24
    Join Date
    Jul 2021
    Country
    UNITED STATES
    State/Province
    Arizona
    Posts
    21
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    0

    Default

    Quote Originally Posted by mymachinery View Post
    #1 you need to find a shop that will laser cut the blank, if only for developing for the bends. I think you do need tool steel because it is hard and you don't need two soft metals rubbing together, and once you have it right, you don't want the die to score, pick up or introduce lines into the part. A U die with a cushioned
    pad to keep the bottom flat, or add set to kill springback plus eject the part. You will want some sort of nest as well that you can adjust. I haven't read far enough to see how many parts you are looking to make. this gets expensive for limited runs unless you are recreating a high value oem part that is unobtainable and have some one willing to pay good money for tham.

    I was talking with a stamping company nearby, they said the custom die would cost around 3500 USD, a chinese company quoted 5000 USD (china cheaper? heh not really). So all in all not so extraordinary expensive, but I'm going down the way to learn how to make it myself.
    I can very well mill sheet metal myself (0.8mm is no problem at all).

    I will have some further discussion with the stamping company to see how far we can do things by ourself.
    I don't see a problem with milling tool steel, and the finer the structures are the smaller the endmills have to be (=the smaller the easier to handle with my CNC).

  5. #25
    Join Date
    Jul 2021
    Country
    UNITED STATES
    State/Province
    Arizona
    Posts
    21
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    0

    Default

    I'm still curious about this part, currently we're getting away with 3d printing a similar part which fits our need.

    Could anyone be so kind and draw a small sketch how a die should roughly look like to form such a part?
    I'd really like to learn more about it.

  6. #26
    Join Date
    Oct 2017
    Country
    UNITED STATES
    State/Province
    California
    Posts
    1,451
    Post Thanks / Like
    Likes (Given)
    480
    Likes (Received)
    484

    Default

    Quote Originally Posted by TJMark View Post
    I'm still curious about this part, currently we're getting away with 3d printing a similar part which fits our need.

    Could anyone be so kind and draw a small sketch how a die should roughly look like to form such a part?
    I'd really like to learn more about it.
    I haven't gone back and reread the entire thread, but I would make it using a tight gooseneck punch and rolla vees on the long bends, and a custom radius punch for the end. The V die used would have to not overhang into the nonflanged region, or a urethane die would work as well.

    I would avoid doing this in one stroke because of the tight 90 channel. If you use a one piece punch or die you will mar the material trying to get full 90s and remove it from the punch. There are multipiece punch or die designs that have wedges that expand under high tonnage to do the final work on the corners, then shrink back up on retract to allow the part to be removed. That becomes more difficult if you have that extra radius to account for, but not impossible.

  7. #27
    Join Date
    Jul 2021
    Country
    UNITED STATES
    State/Province
    Arizona
    Posts
    21
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    0

    Default

    I'm focussing on the u-channel first. I have another part which needs a 7.5mm bent u-channel, goose necks seem to be difficult to handle especially since all the sidewalls need to be equal in size to match some drilled holes.

    How about something like that?

    die.jpg

    the blank will be screwed with a small bar to the top part and pressed into the die body?
    I have no problem to mill some steel here.

  8. #28
    Join Date
    Oct 2017
    Country
    UNITED STATES
    State/Province
    California
    Posts
    1,451
    Post Thanks / Like
    Likes (Given)
    480
    Likes (Received)
    484

    Default

    Quote Originally Posted by TJMark View Post
    I'm focussing on the u-channel first. I have another part which needs a 7.5mm bent u-channel, goose necks seem to be difficult to handle especially since all the sidewalls need to be equal in size to match some drilled holes.

    How about something like that?

    die.jpg

    the blank will be screwed with a small bar to the top part and pressed into the die body?
    I have no problem to mill some steel here.
    That will work poorly. The punch and die will stick, the material will gall, the tonnage required is quite high, and you won't get a full 90. You need a release wedge on the die and a stripper on the punch.

    Forming equal size flanges is not difficult with a gooseneck punch, and you can make adjustments easily where a channel die is useful for one width only.

  9. #29
    Join Date
    Jul 2021
    Country
    UNITED STATES
    State/Province
    Arizona
    Posts
    21
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    0

    Default

    Thank you for following up.

    The u-channel which I'm working on is only 3cm long and 0.8mm thick. I need to bend 2 u-channel parts in total;
    First I'll give the smaller one a try.
    There will be some overhang outside of the die which should allow to remove the part easily.

    The longer u-channel is 120mm long and also 0.8mm thick.

    I have bent the shorter one with a hammer yesterday and the side walls did not match - but the edges looked nice (there's a hole which has to match up), and it seemed to be difficult when doing that manually, that's why I'm trying to make that die now.

    punch.jpg

    when looking at the original parts I can see a small grove at the edges, I guess their channel punch has some stubs at the edge. Is that a common way for channel punches?

    Overall the accuracy I need for that part is -0/+0.4mm, so the tolerance is very high (which should make it a bit easier for me)

    If you have any advice how to make it better for sure I'll pick it up and try to adapt it to my capabilities, I'm an absolute beginner with making such dies. That's actually the first time that I mill steel, I've only worked with aluminium, copper and metal sheet before.
    I appreciate any kind of help!

  10. #30
    Join Date
    Oct 2017
    Country
    UNITED STATES
    State/Province
    California
    Posts
    1,451
    Post Thanks / Like
    Likes (Given)
    480
    Likes (Received)
    484

    Default

    Are you trying to do this in a press brake or a shop press? If it's a shop press you need guide bushings to keep the dies centered and an adjustable block to gauge the back surface off of, otherwise any attempt to form a channel will be difficult

  11. #31
    Join Date
    Jul 2021
    Country
    UNITED STATES
    State/Province
    Arizona
    Posts
    21
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    0

    Default

    I have no particular equipment yet for it (in terms of a press), however I have a small CNC machine as mentioned earlier and some tools which I'd like to abuse for that task.

    - I'd first try to hammer it in (prototype)
    - secondly I might try to press it in with some big screws on the side.

    The volume is quite small, I'd need around 60-100 units of the 120mm and 20mm U-Channel. First of all I'm focussing on the 20mm U-Channel since bending 20mm long/8mm thick material isn't that hard it's all about alignment. About the 120mm U-Channel I'm not sure yet (possibly using the screws to see if my strategy works at all).
    Last edited by TJMark; 10-21-2021 at 12:40 PM.

  12. #32
    Join Date
    Jul 2021
    Country
    UNITED STATES
    State/Province
    Arizona
    Posts
    21
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    0

    Default

    ok the 20mm U-channel worked with a fairly good accuracy and reproducibility (as I was hoping to..)

    Dual side bending seems to work well, single side bending maybe if I'd do some v-grooving otherwise I'd have no faith in that with my amateur tools.

    Next would be the 120mm U-Channel, I also did some experiments with bending a U-channel curve with some scrapped parts I have some idea here too.
    First I'll do the U-Channel, afterwards the curved part.

  13. #33
    Join Date
    Jul 2021
    Country
    UNITED STATES
    State/Province
    Arizona
    Posts
    21
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    0

    Default

    I also succeeded with the 120mm u-channel, I will make some better jigs for bending it next week.
    For now I finally squeezed it into a vise and it folded it just nicely. Double sided bending for sure is easier than single sided.

    Maybe I should also heat up the material before pushing it into the jig.

  14. #34
    Join Date
    Jul 2021
    Country
    UNITED STATES
    State/Province
    Oregon
    Posts
    46
    Post Thanks / Like
    Likes (Given)
    49
    Likes (Received)
    12

    Default

    Casting the thing with a follow up on the milling machine may be another option. Copper is a the top range for cheap electric melters, but they can handle it nonetheless. So about $200 in tooling for that path, and some experimentation with mold making, possibly using 3D printing and lost-pla method.


Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •