Flying Shear Application/zh-hans

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简介

飞剪应用的任务是将不断移动的材料切割成预定长度。与冲切不同，切割是在运动中完成的。在飞剪应用中，运动任务必须在主轴和从轴之间保持同步一段时间，然后尽可能快地返回到初始位置，以准备下一次切割。可以可选添加用于长度校正的传感器。虽然这是作为切割应用程序呈现的，但该示例可用于其他应用程序，例如在产品上贴标签或打印标记。应用程序设置在达到同步点时的输出。 该输出可以启动切割机构，但可以启动任何其他打印或贴标签设备。

应用图

飞剪应用的近似运动曲线如下所示:

运动曲线

运动分为三个阶段。第一阶段包括停车时间。到同步点的滑架加速度是滑架应该与主轴的切割长度同步的阶段。第二阶段或切割由切割过程完成所需的时间决定。第三个也是最后一个阶段是滑架回零位置。 我们假设材料流速是恒定的，已知：Vm。 此外，我们假设加速度和减速度值都相同。 要获取凸轮轮廓参数，请使用以下公式：

这里，已知的是L，T和A.所请求的是分析器参数tacc，tdec，v。使用上述等式，用于飞剪应用的代码如下（使用从Cut To Length示例的VTProfile和ProfileLTA例程）：

程序

common shared c1 as cam

dim shared toolong   as error "The given cut length is too long for the given slave accel."
dim shared toofast   as error "Slave axis can not move that fast"
dim shared tooshortw as error "Waiting period too short"
' Shared profile parameters:..............................................
dim shared lprof        as double ' total legth 
dim shared aprof        as double ' acceleration used
dim shared vprof        as double ' cruise velocity
dim shared t_acc_prof   as double  ' acceleration duration
dim shared t_dec_prof   as double  ' end of cruise phase
dim shared t_tot_prof   as double  ' total velocity trapeze duration
'.........................................................................
program
 dim i  as long

 ' Process data
 dim Vmaster                      as double
 dim CutLength                    as double
 dim CutTime                      as double
 dim DwellTime                    as double
 dim BackLength                   as double
 dim WaitLengthMaster             as double
 dim WaitLengthSlave              as double
 dim DecLength                    as double
 dim CutPath                      as double

 ' Cam profile parameters
 dim t_acc                        as double
 dim t_dec                        as double
 dim t_back                       as double
 dim t_tot                        as double
 dim vback                        as double

 ' Variables used in cam computation
 dim t                            as double
 dim dt                           as double

 WaitLengthMaster  = 15  ' Length in mm that is passed before the carriage is synchronized
 Vmaster           = 60  ' mm/sec - velocity of the material
 CutLength         = 70  ' mm of the master material feed
 CutTime           = 0.2 ' Time 200 ms needed for the cut

 with A1        'A1 = Carriage (Slave)
     Attach
     Slave=0
     FirstCam = none
     CreateCamData 1000 c1               ' Creating 1000 points  in the cam 
         
     CutPath = Vmaster*CutTime           ' Path traveled during cutting process
     t_acc = WaitLengthMaster/Vmaster    ' end of acceleration
     DwellTime = t_acc - Vmaster/acc     ' dwell duration
     if DwellTime < 0 then
        throw tooshortw
     end if
     
     t_dec  = t_acc + CutTime               ' Time to start deceleration.
     t_back = t_dec + Vmaster/acc           ' Time to starts carriage return
     t_tot  = CutLength/Vmaster             ' Total time of the movement is
     WaitLengthSlave = 0.5*Vmaster^2/acc    ' Path passed by slave during waiting
     DecLength       = 0.5*Vmaster^2/acc    ' Path passed by slave during deceleration
     BackLength      = CutPath + WaitLengthSlave + DecLength ' Total movement length
    
    ' Setting for the first trapeze (forward carriage motion)
     lprof           = CutPath + WaitLengthSlave + DecLength
     aprof           = acc
     vprof           = Vmaster
     t_acc_prof      = t_acc  - DwellTime
     t_dec_prof      = t_dec  - DwellTime
     t_tot_prof      = t_back - DwellTime
    
     dt = t_tot/(c1.size-1)
     t = 0
     while t <= t_back
         i = round(t/dt) +1
         c1.MasterData[i] = t*Vmaster
         if t < DwellTime then
              c1.SlaveData[i] = 0 
         else  
              c1.SlaveData[i]  = VTProfile(t-DwellTime)          
         end if
         t = t + dt
     end while
    
    
     ' Next trapeze (carriage return)
     lprof           = CutPath + WaitLengthSlave + DecLength
     call ProfileLTA(lprof ,t_tot - t_back, acc)
     while t <= t_tot
         i =     round(t/dt) +1
         c1.MasterData[i] = t*Vmaster
         c1.SlaveData[i]  = BackLength - VTProfile(t-t_back)    
         t = t + dt
     end while
     c1.MasterData[c1.size] = CutLength
     c1.SlaveData[c1.size]  = 0
     


    ' Setup the camming
     c1.Cycle     = -1 ' endless camming
     FirstCam     = c1
     MasterSource = A2.Pcmd
     GearRatio    = 1
     Slave        = cam
     En = ON
     Detach A1
 end with
 
 Print "Flying Shear Ready"
 
end program

'.................................................................................
' Velocity Trapeze gernal purpose profile function
' uses shared variables:
' t_acc - time where acceleration ends (cruise starts)
' t_dec - time where deceleration starts (cruise ends)
' t_tot - end of movement
' aprof - accleration/deceleration value
' vprof - cruise (max) velocity
' lprof - total movement length
function VTProfile(byval t as double) as double
  select case(t)          
     case is <=0
      VTProfile = 0 
     case is <= t_acc_prof
      VTProfile = 0.5*aprof*t^2
     case is <= t_dec_prof
      VTProfile = 0.5*vprof^2/aprof + (t-t_acc_prof)*vprof
     case is < t_tot_prof
      VTProfile = lprof - 0.5*aprof*(t_tot_prof-t)^2
     case else
      VTProfile = lprof
   end select
end function

' Velocity Trapeze pre-calculation routine
' Input: Length, Total time, max Accleration
' Global used: Vmax

sub ProfileLTA(byval L as double ,byval T as double, byval A as double)
    dim sqr as double
    
    with A1
      aprof = A
      sqr = T^2 - 4*L/A
      select case (sqr)
      
        case is < -0.004 ' less then 4ms
            throw toolong
            
        case is < 0
            ' In cases of numeric computation errors (high accel. values) this could be a small
            ' negative number. In order to avoid math error the value is cut to zero.
            sqr = 0          
            
        case else
            sqr = sqrt(sqr)
      end select
      
      vprof = 0.5*A*(T - sqr)
      if vprof > vmax then
            throw toofast
      end if
      
      ' Compute fixed points in time (end of acceleration, begin of deceleration)
      t_acc_prof = vprof/A
      t_dec_prof = T - t_acc_prof
      t_tot_prof = T
      
    end with
end sub

记录曲线