second secondary connecting rod which is rotatably connected at the other end with the second slide yoke the second slide yoke is installed on the second guide rail and connected slidingly relative to the second guide rail which is fixed relative to the frame and the second slide yoke is fixedly connected with the second ram fourth the first throw of crankshaft the first primary connecting rod the first swing lever the first secondary connecting rod the first guide rail the first slide yoke and the first ram are located at one side of the crankshaft 14 constituting a first ram drive mechanism the second throw of crankshaft the second primary connecting rod the second swing lever the second secondary connecting rod the second guide rail the second slide yoke and the second ram are located at the other side of the crankshaft 14 constituting a second ram drive mechanism a rotation support point of the first swing lever and a rotation support point of the second swing lever are arranged in a cross sectional plane of the crankshaft 14 and symmetrically about a vertical line through a rotation central point of the crankshaft 14 that is as shown in fig5 the first ram drive mechanism and the second ram drive mechanism are arranged symmetrically about a vertical line through the rotation central point of the crankshaft 14 thus forming the first layout as shown in fig5 because the first ram drive mechanism and the second ram drive mechanism share one crankshaft 14 and are arranged in the opposite direction when the two ram drive mechanisms work.