Time to build a machine to automate a process, Anyone want to help my first journey? - Page 4
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  1. #61
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    Quote Originally Posted by plastikdreams View Post
    I don't think it's crazy, I'm sure it's possible, but is there a better, more cost effective way to meet the goal.

    I'm all ears. As long as it doesn't involve using an existing CNC mill that costs $100,000

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    If you don't go molded...

    parts on a side link only conveyor indexed to a stiff lifting bottom plate that references on the part's center though hole and the two c'bores, a matching top plate traps the part.

    Both top and bottom plates are rotatable 90 degrees by some sort of Geneva mechanism in the top plate ;-) (Or use steppers or servos etc,)
    Simultaneous opposed drilling from only two sides, then index the part 90 degrees.

    After the holes are produced, the lower plate retracts to return the part to the conveyor . Lather rinse repeat,

    Smart packaged servo or stepper drives would make the coordination easy, Only two drilling spindles trims the mechanism complexity.

    Just thinking out loud.

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    I dont follow the lifting from the bottom portion. Do you have any photos or videos of stuff online by chance?

    I plan to use clearpath servo motors and use the PLC to drive them since they are already integrated into that PLC unit.

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    Quote Originally Posted by as9100d View Post
    Holes have to be concentric within .001 and hole size is .196 through with a .206 to .800 deep on 3 sides. Mold is only as expensive as the person making it..which will be me and I guess I work for free. Part is 1.11" thick.
    I don't see how you can get away from not having four drills. Simple way is a nest for the part with locating features surrounded by the four drills. How to get the part in the nest. Hand placement, machine placement. In either case the part will have to loaded either from the top or bottom. What several has suggested is bottom loading. The part is loaded on to an elevator and moved upward with an air cylinder. Part is pushed against locating pins or plate for vertical alignment.

    Tom

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    Completely agree. Even if I were to explore molding these...I would still need to drill the holes. More I think about it, injection molding just wont work with the two tight tolerances on the bore and outside boss.

    I need to find some photos or video of a bottom loading setup with a conveyor. I'm having trouble wrapping my head around how to get the part off the conveyor and back on easily.

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    or call a company that builds automated multispindle drills? Controlled Automation, Pendinghause, Ficep, MegaFab, Mazak….
    With some ebay creativity, and scrap yard engineering you can build for less than any of machine builders would charge- first get a design concept down- starting with plc is not the datum of the design. FlashCut will design and build a control panel and windows hmi cheaper than you can build one if you include the aspirin and overtime it will take you. Each axis cost +- 1000 to self build, 4 spindles + orientation (spin) + pick/place + clamp is 7 axis.

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    I have no interest in calling someone else to do the work. I have all of the tools needed to accomplish this task, I wouldnt have ever outsourced programming, cad, or any other aspect of machining when I first started on this journey...No reason to start now.

    There are more automation projects to be done and I have no doubt that after I get my feet wet with this project, the next ones will be easier.

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    Leeson self feeders


    Sent from my iPhone using Tapatalk Pro

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    Google shows nothing for that.

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    Extrude it and slice it on a saw


    Sent from my iPhone using Tapatalk Pro

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    Quote Originally Posted by as9100d View Post

    There are more automation projects to be done and I have no doubt that after I get my feet wet with this project, the next ones will be easier.
    One way to simplify the rotary transfer machine design is to skip the turntable and motor assembly and instead use a off the shelf product. The NSK Megatorque servo motors are hollow shaft vertical motors with preloaded cross roller bearings. These servos can index with arc second accuracy and depending on the model can support several thousand pounds. In the larger sizes they are used at the base of industrial robots for the swing axis and in smaller sizes for rotary transfer mechanisms in the semiconductor industry. The mid range size servos are sold with extra heavy duty bearings for direct drive fourth axes on machining centers and welding manipulators.

    These servos are expensive. However the Ebay listings have the smaller semiconductor industry sized servos and drives available in the thousand dollar range. Some are new and some are used. The motor should always be purchased with the drive. This was required for the earlier versions. It is not a requirement for the later designs. This type of drive would have the most flexibility in use and would be the easiest to program.

    For your application a rotary transfer drilling center provides processing speeds much faster than you need.

    A much simpler approach would be to make a aluminum cassette with, for example, 30 shelves for 30 disks. The cassette is vertical and has four sides. The cassette is mounted on a elevator screw as described earlier and indexed in steps of 1.15 inches. There is a pneumatic pusher that ejects one part from the cassette into the drill station, a indexer pin assembly drops down to clamp and align the part in the drill station, the drilling cycle runs., the pin assembly lifts up, and then a second pusher shoves the part back into the cassette. The cassette is run through all 30 shelves and then stops.

    A budget version of this device would only have one drill head. The four holes would be drilled by running the cassette through the machine four times each time turning the square four sided cassette 90 degrees.

    The cassette is loaded with a temporary orientation bar in place to keep the parts approximately aligned. The bar is withdrawn after the cassette is placed on the indexer. The final alignment is done by the drop down pin assembly.

    This design only has one motor and three pneumatic pistons for part handling.

    Your machining time for two parts is four minutes so a 30 shelf cassette would hold one hours worth of parts The drill operation could be set up next to the mill and keep the operator occupied while the parts are being machined. Loading the cassette does not add any additional time to the process. The Haas operator needs to put the parts someplace already. Instead of stacking them on the table he will be stacking them in the cassette.

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    Quote Originally Posted by Robert R View Post
    On way to simplify the rotary transfer machine design is to skip the turntable and motor assembly and instead use a off the shelf product. The NSK Megatorque servo motors are hollow shaft vertical motors with preloaded cross roller bearings. These servos can index with arc second accuracy and depending on the model can support several thousand pounds. In the larger sizes they are used at the base of industrial robots for the swing axis and in smaller sizes for rotary transfer mechanisms in the semiconductor industry. The mid range size servos are sold with extra heavy duty bearings for direct drive fourth axes on machining centers and welding manipulators.

    These servos are expensive. However the Ebay listings have the smaller semiconductor industry sized servos and drives available in the thousand dollar range. Some are new and some are used. The motor should always be purchased with the drive. This was required for the earlier versions. It is not a requirement for the later designs. This type of drive would have the most flexibility in use and would be the easiest to program.

    For your application a rotary transfer drilling center provides processing speeds faster than you need.

    A much simpler approach would be to make a aluminum cassette with, for example, 30 shelves for 30 disks. The cassette is vertical and has four sides. The cassette is mounted on a elevator screw as described earlier and indexed in steps of 1.15 inches. There is a pneumatic pusher that ejects one part from the cassette into the drill station, a indexer pin assembly drops down to clamp the part in the drill station, the drilling cycle runs., and then a second pusher shoves the part back into the cassette. The cassette is run through all 30 shelves and then stops.

    A budget version of this device would only have one drill head. The four holes would be drilled by running the cassette through the machine four times each time turning the square four sided cassette 90 degrees.

    Your machining time for two parts is four minutes so a 30 shelf cassette would hold one hours worth of parts The drill operation could be set up next to the mill and keep the operator occupied while the parts are being machined.
    I like this idea a lot. Question is....can you draw a rough sketch on paper possibly? I have an idea of what you mean but id like to make sure im on the same page.

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    The idea is not original. It has been used in the semiconductor industry for the past 50 years to handle wafers.The cassette design has evolved over the years as the wafers went from 3 inch diameter up to twelve inches The designs have also become much more complex to exclude contaminants from the wafer as the size of the transistors on the wafer have shrunk.

    If you would like to see some actual hardware spend a few minutes using search phrases such as "wafer handler", "wafer cassette" "wafer transport", "wafer elevator".

    My exposure to this was 30 years ago. The mechanisms were crude by today's standards. They were using stepper motors, cold rolled lead screws with plastic spring loaded nuts, plastic bushing guide rails, and cheap pneumatic pistons with adjustable hard stops to control travel distance.

    The success of the design depends on the cassette and the pusher bar. . The parts need to stay in roughly the right orientation as they slide to the drill station. If they drag a bit as they slide they may rotate enough to cause a miss by the alignment pins. So the pusher bar needs to have a feature which meshes with the part surface to prevent part rotation or sliding to far to one side.

    At the drill station there needs to be a entrance funnel so that the sliding part arrives centered in the station.

    In some industries they use digital cameras and image recognition software to look at the part to determine its orientation and position. After processing the same software will be used for quality control to automatically verify hole location and maybe hole depth.

    It the 1990's the software, image capture board for the PC, and the camera would cost about $5000. It should be much less expensive today.

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    cassette-1.jpg


    something like this yes?

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    That's it. In the semiconductor business the cassette is a injection molded part .

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    What do you think about igus plastic linear guides for the up/down of the cassette?

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    I think you're too quick to dismiss molding.

    The two close tolerance features could be machined after molding. Another handling problem, for sure, but that's right up your alley.

    Some time with a moldmaker and a molder as consultants/handholders could work the process out and reach a more accurate final molded cost.

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    Quote Originally Posted by as9100d View Post
    What do you think about igus plastic linear guides for the up/down of the cassette?
    No. Cheap crap for non essential motion. They aren't even much cheaper than real bearings.

    There most certainly are companies out there there build dedicated drill only machines, but they won't be cheaper than another (new) Robodrill.

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    So no love for the idea of using a horizontal indexer in the original machine along with one or two powered horizontal drills to add the side holes? I still think that's worth looking into for a "done in one" option if molding isn't a good path.

    For operator fatigue, add some low-cost cylinders to the doors to open and close them (with appropriate safeties) , and maybe an in-machine air blast to clean the fixturing before part removal. If this part must be machined do it in one setup and if the process is made simple enough perhaps a robot un/loader can be added.

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    Quote Originally Posted by as9100d View Post
    What do you think about igus plastic linear guides for the up/down of the cassette?
    Years ago I worked at a company that used the plastic lined metal shell bearings running on 2 inch diameter Thompson case hardened centerless ground bar in a vacuum chamber. It was a elevator that cycled and then did a rotary index once every 5 seconds 24 hours a day six days a week. The bearings required no oil and did not generate any debris while sliding. One of the machines was disassembled for repair after a few years of service. The plastic bearing sleeves showed very little wear. The plastic sliding materials have improved since then. The only drawback to their use is that you are limited to a few hundred pounds load per square inch of the bearing surface.

    Keep in mind that these bearings need to be kept away from dust or shop grit. If contaminates get trapped between the plastic liner and the shaft they will fail. The same is true of any other bearing design.

    In looking further at the geometry of the cassette part feed it has become apparent that the design is limited to two drill stations. The elevator ,cassette, and push in bar occupy the 12 o'clock position. The part return push bar occupies the 6 o'clock position. The drill heads are at the 3 o'clock and 9 o'clock positions.
    It is possible to overcome this limitation at the expense of a much more complicated part transfer from the cassette to the drill station. It is not worth the trouble.

    The prototype cassette is made up with four 37" long 3/8 diameter bars with threaded ends. The bars screw into a wide base square aluminum block with tapped holes at the four corners. At each bar a aluminum standoff 1.20 inches tall with a 3/8 bore is dropped down. A.06" thick aluminum plate with four holes is dropped down next to form one shelf. The stack is repeated for all 30 shelves. The idea is to limit the cassette to roughly 36" in height so that it and the elevator mechanism can fit under a desk height table. The table supports the drill station.

    The operator has a set of push buttons for a fast elevator up and down to make part loading easier. Once the cassette is loaded the elevator will switch over to a index operation.

    The cassette needs to have a part alignment feature. This could be two temporary bars that are dropped down from the top of the cassette into the part u-shaped slots. Once all 30 parts are aligned the bars are carefully pulled out. Or it could be two fixtures that sit on the table top and slide against the cassette sides. The fixtures have projections that fit into the shelf that align the parts.

    Or it is some very clever feature added to the cassette shelf plate that does the alignment without interfering with the part push out/ push in operation of the cassette. The feature might be a set of spring loaded hinged alignment blocks that swing out and release the part when the pusher bar is in operation. Plan on using two more pneumatic pistons to release the blocks.

    The spring loaded shelf clamp is required if you have multiple cassettes that are storing parts waiting for processing. It allows the cassettes to be moved without having the parts fall out.


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