How To Set Bar Start / Stop Positions
How To Set Bar Start / Stop Positions
This is a commonly asked question from stampers when they
first start using T-SIM for simulations and optimizations. It can be
challenging the first time you do this but, after a job or two, it should be no
problem. In your T-SIM Press Setup Package, you'll refer to Step 1 (Transfer
Setup Information). We provide to you the bar locations that were used in your
simulation as shown below.
The diagram on the left shows you the key for the dimensions
directly below it. This will tell you the ACTUAL physical position
of the bars, NOT the values you will enter into your
controller! The challenge is that different transfer manufacturers and models
set their bar positions values in the controller in many different way. Below
we'll explain how to determine the values for each axis by providing some
examples and instructions. You can determine these "Zero" or
"Start" values with any project in the press or with it
empty...either way works.
Lift
Determining the lift (or (Z) axis) values
is the easiest of the three axis. The lift zero is typically set to the top of
the bolster (in which case you can use the (D) value provided in your Press
Setup Package) OR it is the "Park" position (which could be any
distance above the bolster). Below is an example of a zero position being
something other than the top of the bolster.
Instructions: You can determine this value by measuring the distance from the bottom of the main transfer bar (D) and comparing it to the controller value you have for the Z (or lift) axis. Once you have determined the "Zero Position" for the Lift axis, document this for use in any future projects.
Example: The "zero position"
for the lift axis in your controller may be 350mm above the bolster
of the press. Using the setup values shown in the image above, this would mean
your Z start position would be 48mm and Z finish position would
be 223mm (48mm + (E) value of 175mm) [ D= 398mm
- actual zero bar height above the bolster 350mm making the bar
start position the difference of the two (398-350 = 48mm)]
Clamp
Clamp axis ( often referred to as the (X) or (Y) axis)
can be setup several different ways. (1) - Some transfer
systems have the "Park" position or "Home" position as zero
and the closer to the centerline of the press you move, the higher the
"clamp position" value will show in the controller. (2) -
Others have the "zero" set to the minimum clamp position (bars as
close together as they can be - minimum bar spread) and the further apart they
are, the larger the value is. (3) - Yet another possibility is
that the zero is the centerline of the press and values are measure from there
to the face of the bars.
In your T-SIM Press Setup Package, you will see
the ACTUAL physical dimension between the face of the main
transfer bars (A) - Bar Closed Position & (B)
- Bar Open Position (see image above) If your controller shows start and stop positions as the actual bar spread, then you can simply use the T-SIM values in your controller.
IMPORTANT: one more thing to be aware of... some
transfer systems start / stop values represent one side of the transfer system
(where a Start @ 200mm, End @ 350mmmm would be a clamp stroke of 150mm per
side) while other start and stop positions represent the actual spread of the
bars (Start @ 36" End @ 52" which would be 16" total travel but
only 8" per side). All this to say, clamp can be a little more tricky to
determine than lift but, rest assured, once you know your system, converting
the values in T-SIM to your controller values will be no problem!
Warning: Values are only accurate if automation design was done EXACTLY to the bar positions shown in Step 1 of the Press Setup Package. Even when these values are used to build the automation, small variations in build accuracy can impact the final bar positions in your controller. You may have to adjust bar positions slightly from the T-SIM values because of this.
Instructions: Measure the actual distance between the bars in the home position and again when the clamp in motion is complete. Document the actual measurement AND what is shown for the current position in the controller for each of these. With the two measurements and corresponding controller values, you should be able to determine what setup your transfer system has (1,2, or 3 from above), how the clamp axis is being measured (per side or total), and if zero is on center line of press, home position, or @ minimum bar spread position.
Example-1: Zero position
measured bar spread = 1800mm - Clamp Stroke (C) = 342.9mm.
Using the values
from the Step 1 above (Bar Open = 1689.1 - Bar Closed = 1003.3)
Bar Start Position: 1800mm (zero distance) - 1689.1mm (B
value) = 110.9mm difference. Because the clamp axis is "per
side" in this example, we'd divide that by (2) to get 55.45mm as the Clamp Start Position and adding the clamp stroke 342.9mm to that = 398.35 Clamp End Position.
Example-2: Zero position measured bar spread = 1000mm - Clamp Stroke (C) = 342.9mm.
Using the values from the Step 1 above (Bar Open = 1689.1 - Bar Closed = 1003.3)
Bar Start Position: 1003.3mm (B value) -1000mm (zero distance) = 3.3mm difference. Because the clamp axis is "per side" in this example, we'd divide that by (2) to get 1.65mm as the Clamp Start Position and 344.55mm Clamp End Position.
Example-3: Zero position measured bar spread = 1000mm - Clamp Stroke (C) = 342.9mm.
Using the values from the Step 1 above (Bar Open = 1689.1 - Bar Closed = 1003.3)
Bar Start Position: 1003.1mm (A value) / 2 = 501.65 mm. 1689.1 (B Value) / 2 = 844.55mm Clamp End Position.
Pitch
The pitch axis positions can be setup one of two ways in a transfer system. Some transfers are "Uni-directional" meaning they move from the home position in one direction (L to R / R to L) from zero. In this case you can simply use the values provided in the T-SIM Press Setup Package for "Pitch Start" & "Pitch Complete".
If your press is a "Bi-directional" press meaning it is zero at 1/2 of total available pitch and moves negative in one direction and positive in the other from that zero position. For example, if the total pitch of the project was 500mm, start by taking that and divide it by (2) [500 / 2 = 250mm]. If the Pitch Start position in the Press Setup Package were zero (0) then the Pitch Start in your controller would be -250mm and Pitch Complete in the controller would be +250mm. If the Pitch Start from the Press Setup Package was 50mm, The controller Pitch Start would be 200mm and the Pitch Complete would be 300mm. You simply add the start value to both the negative start position and to the positive end position.
Below is an example based on the sample data we have been using from the Step 1 image with a "bi-directional" transfer.
Example: Pitch = 482.6mm Pitch Start = 10mm
482.6 (Pitch) / 2 = 241.3mm
Pitch Start = -241.3mm + 10mm (Pitch Start from press setup package) = 231.3mm
Pitch Complete = 241.3mm + 10mm = 251.3mm
Pro Tip: If you create a simple excel sheet with the documented values for your zero positions and use the equations we've provided in the above descriptions and examples, you should be able to easily convert the values you receive in your T-SIM press Setup Package to your specific press Start / End position. We have included the attached Excel calculation sheet (Calculate Bar Positions.xlsx) to help get you started. Simply fill in the light blue cells on the various tabs and it will calculate your controller positions in the light green cells.
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