They won't let you draw severance while drawing your pension. But, you can delay your pension until after your severance has run out. Delaying your pension by 6 month may increase your pension payment. Also, your severance payment will probably be higher than your pension payment.
But since HW has so many pension plans at the moment (which eventually get to zero as we oldsters die off), I highly recommend that you obtain the SPD (Summary Plan Description) for the pension plan that you have and read it for yourself. Also, get the SPD for the severance plan and do the same. That should get you a much better answer than you'll likely get on an anonymous Internet forum.