When the upper die of Yuan Jinfang CNC bending machine falls to the speed conversion point, Y 1-Y2 is not parallel, and the numerical difference displayed on the display is about 15. What's this

Do you think it is parallel (one side goes to the bottom first) when it goes to the bottom slowly (without pressure)? If it is not parallel at this time, please check whether the suspension spring of the oil cylinder is loose or whether the gasket on it is misplaced. If there is nothing wrong with this piece, can you turn off the hydraulic pressure and see if one side of the knife has fallen off? If the knife is dropped, the sealing ring of the oil cylinder will be broken. If the knife didn't fall, it fell parallel to the end, then adjust it in the program!