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Phase converter wont run my shear

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  • Phase converter wont run my shear

    I just bought a high end Phase converter, 40 HP to run my 20 HP shear, The shear cap. is 1/4" x 10' and it will cut 12" of 1/4" without a problem but when you try doing more than that you have to hit the pedal about 3-5 times to cut 5' of 1/4".

    I still have to check blade gap, but the edge after the cut feels normal, the blades are sharp, no nicks that I could feel.

    I called accurpress and the guy acted like ( Ya this is common when trying to run a shear off a phase converter )

    The legs of the phase converter are where the manufacturer said they should be.
    The made phase is measuring about 256 Volts when measuring from L1 to 3 and L-2 to 3 , The voltage between L1 to 2 is 242 so that seems good from what the Phase converter manufacturer said, The made phase should be higher when measured between legs.
    They said don't measure from leg to ground because that would be an in accurate measurement.

    If indeed the phase converter does not put out full capacity, the guy from accurshear said my only other option would be to go with a smaller pump which would cause the shear to operate slower but would allow me to maintain the high pressure required to shear 1/4" which would require less HP. which seems to be the problem.

    I will call the phase converter company tomorrow to see what they have to say.

  • #2
    Don't go with the smaller pump. The slower the cut, the more it will pull and curve the cut. I have previous experience with this. It might be gruesome, but the French had the right idea with the guillotine a couple hundred years ago.
    Obviously, I'm just a hack-artist, you shouldn't be listening to anything I say .....

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    • #3
      Your voltages seem OK, but I'm wondering about the capacity of your incoming power line. IIRC, a 40 hp single phase RPC idler motor will need something like 100 amps and the 3 phase 20 hp motor would have at least half of that.

      If you aren't kicking a breaker, I assume that you have sufficient power, but it could be that your supply is marginal so that you won't be able to get sufficient current for both motors. Just a guess on my part, however.

      My experience with RPCs is limited to usage on a milling machine. I have a 7.5 hp unit that I built about five years ago. It's powering a 3 hp, 3 phase mill. Both motors together draw 19 amps from a 30 amp dedicated line.

      Keep us posted.
      Last edited by Synchroman; 12-22-2014, 06:17 PM.
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      • #4
        Check the amps

        I would think that you want to take voltage and amp readings under load. Analog meters might be a better choice with varying conditions, as digital meters don't respond super-quickly. Or use both and cross-check the results.

        I would not call the company without amp data.

        If you don't have a clamp-on ammeter it is time to buy one.

        It is of course possible that the motor on the hydraulic pump is not working correctly; if the amps vary a lot from phase to phase, I would regard that as a bad sign.

        40 hp x 746 watts/hp = 29840 watts.

        29840 watts / 240 volts = 124 amps. That is a lot of amps, which certainly suggests that you need to look at the supply. However, given that it is powering a 20 hp motor, the actual amps may be more like 70 amps at full load. Obviously the manufacturer of the converter should be able to help you understand what you should expect.
        Syncrowave 200, Millermatic 211, Victor torch, Propane forge....

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        • #5
          JS Fab, This is not the news I wanted to hear, The manufacturer of the shear is the one that recommended the smaller pump, I will have to question the quality of the cut.

          I'm only able to make around 2000 psi when I need 2500-2800 according to the manufacturer and should be able to make 3500 max capacity for harder material

          This is what the manufacturer said.

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          • #6
            Are you getting enough amperage to the converter? Are the wires getting warm? Is the converter getting warm? is the shear motor getting warm? Is this a rotary converter.....? How much $ for a single phase motor? Good Luck....It will be great to have a shear...

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            • #7
              How many hours a day/week will you use the shear? Perhaps you should look into an engine driven hydraulic power source.---Meltedmetal
              ---Meltedmetal

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              • #8
                I suspect you are running out of power at the box as well. Might have to look at your house box and see if you have the capacity at the main panel, check that under load as well. If no problem there, you may need to upsize the wire.

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                • #9
                  What model of accupress?

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                  • #10
                    I run a 50 Hp converter to run a 30 hp 3 phase motor that operates my 12 ft 3/8" shear. Takes 200 amp service to start up the 50. Your problem could start at the transformer. I had mine upgraded to 600 amp service. I think I am going to get 3 phase hooked up to it,too much of a power hog.
                    2- XMT's 350 cc/cv
                    1- Blue star 185
                    1- BOBCAT 250
                    1- TRAILBLAZER 302
                    1- MILLER DVI
                    2- PASSPORT PLUS
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                    1- DYNASTY 280 DX
                    1- MAXSTAR 150 STL
                    1- HF-251 BOX
                    1- S-74D
                    1- S-75DXA
                    2- 12-RC SUITCASES
                    1- 8-VS SUITCASE
                    2- 30 A SPOOLGUNS

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                    • #11
                      Rated at 1/4" x 10' it should cut through no problem. Did the shear cut well for the last owner & did you see it work? Reasons for shear not cutting besides power are, dull blades, blade gap incorrect, blade rake incorrect, pump psi not correct.

                      1) You said blade sharpness seems o/k & the cut does not have a large burr. Appears to be good but easy enough to check if you have the spec. Put it in inch mode & check at several areas with a feeler gauge.

                      2) Does it have a rake adjustment? On the Cincinnati I used to use if you had the rake set for 16 ga it would not cut 1/4". The more rake the less material the blade is actually cutting at any given time.

                      3) Can you turn up the pump? Is the pressure you are reading while cutting/under load or just idling?

                      If the hold downs are working properly I don't see an issue with blade speed one way or another.
                      MM250
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                      MM200 black face
                      Whitney 30 ton hydraulic punch
                      Lown 1/8x 36" power roller
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                      • #12
                        low pump psi...

                        Originally posted by MMW View Post
                        Rated at 1/4" x 10' it should cut through no problem. Did the shear cut well for the last owner & did you see it work? Reasons for shear not cutting besides power are, dull blades, blade gap incorrect, blade rake incorrect, pump psi not correct.

                        1) You said blade sharpness seems o/k & the cut does not have a large burr. Appears to be good but easy enough to check if you have the spec. Put it in inch mode & check at several areas with a feeler gauge.

                        2) Does it have a rake adjustment? On the Cincinnati I used to use if you had the rake set for 16 ga it would not cut 1/4". The more rake the less material the blade is actually cutting at any given time.

                        3) Can you turn up the pump? Is the pressure you are reading while cutting/under load or just idling?

                        If the hold downs are working properly I don't see an issue with blade speed one way or another.
                        If you are not building the correft psi, and the motor is not tripping the breaker, i would lean towards a weak pump, or a bypassing cylinder, if it were me, i would cap one end of the presses cylinders, and see if psi returns. It is very likely the cylinder is leaking internal, im sure there is two cylinders which push the shear bar down, they are likely teed together. Also i would be watching the output of the converter as the shear is reaching max psi, if the voltage output is good then im questioning how the converter could be at fault. Now the easiest way to test the hydraulics would be with a flow meter, it would prove a weak power unit instantly. If you need more testing procedures on the hydraulics look on the unit and see if it has a circuit diagram, i can walk you through were to cap, and where to adjust.
                        Kevin
                        Lincoln ranger 305g x2
                        Ln25
                        Miller spectrum 625
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                        • #13
                          What do the techs at the converter manufacturer think?? (American Rotary??)
                          .

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                          • #14
                            Phase Converter

                            Have you check to see if the pump motor is rotation is correct? With 3 phase it is very easy to have your motor turning the wrong direction.

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                            • #15
                              Okay, The shear is rated for 1/4" x 10' its a 1989 manufacture date, The wires are all properly sized, I checked amp draw as I stall out the motor and its pulling 67-68 amps, the pump is spinning the right way. and its stalling out with max pressure at 2000 psi.

                              I have a high end electrician coming out to verify everything, I don't want to call American rotary until my electrician can verify everything.

                              I talked to the pump manufacturer and they can drop my pump down from 16 GPM to 11 gpm which will allow me to get the psi that I need.

                              I haven't gaped the blades yet but since it will still cut a limited amount of 1/4" plate before it stalls the plate edge seems good based on the 1/4" x 12 accurshear I use at my buddies shop.

                              Im not sure if I can change the rake but since I cant make more than 2000 psi I doubt that rake is the issue.

                              Yes all the hold downs seem to work good.

                              I hope Ive answered all the questions.

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