Increasing Production of In-die Tapping Operation with Servo Press

Increasing Production of In-Die Tapping Operation

How much faster can a servo press run an In-die tapping application than with a traditional mechanical press using the following traditional process requirements?

Press:  10" stroke (Box B14)

Tap size:  M8 x 1.25 

Material:  1008-1010

Part thickness:  Extruded hole with tap length of .250"(Box B8)

Production Speed:  38 SPM (Box B169)

Press stroke used for tapping:  5.30" (Box B98)

Gear Ratio:  1.9:1(Box B98)

Having to use a full press cycle on a traditional mechanical press, 4.70" of press stroke is used for feeding the strip into progression.  However, using a servo press’s pendulum (half) motion http://youtu.be/i7wSG5UHJec, we can eliminate any unused stroke length and gain increased production rates without having to change current process specifications.

In this scenario, only 1.5” of stroke length is necessary to advance the strip into progression.

Combine this with the 5.30” required for tapping, our necessary stroke length is 6.80”.  By removing the 3.2” of stroke, we will increase production rates from 38spm to 54 spm.

Figure 1

Here’s how. 
A test was performed on a SEYI SD1-220T direct drive servo press with a maximum stroke length (TDC) of 9.84”.  In Pendulum (Half) mode, we can virtually re-adjust TDC to meet the required process stroke of 6.80” or 173mm:  This re-adjusted stroke is programmed into the pendulum (Half) motion profile as setpoint “P1” (see figure 1). 

When the press is engaged, we descend from TDC (250 mm/9.84”) to P1 (143mm/6.8”) at 50 spm (rated max press spm).  P1 is set to 173mm (6.81”) above BDC.  We then descend from P1 (173mm) to P2 (135 mm) at 50 spm.  The distance between P1 and P2 is the 1.5” that we need for the feed progression.  We want to use 50spm between these two pints in order to save as much time as possible.  At P2 (135mm/5.3”), our tapping begins.  We slow the press speed down to 38spm to match the process requirements. We carry this through to bottom dead center (P3), and then back up to P4 at the same rate.  From P4 back up to P1, we increase the speed back to the rated 50 spm.  Note that “0” is used instead of programming 50. The controller software knows that, upon ramp-up, if a 0 is used, it means maximum press spm.  You could just as easily program 50 spm and get the same result.

Figure 2 shows indicates the forming curve and at what points the feed progression and tapping occur.

Figure 2

To see the video of new adjusted output, go here. http://youtu.be/_ALcszI7SU8