High-frequency preheater for preheating plastic workpiece and machining method of high-frequency preheater

The invention discloses a high-frequency preheater for preheating a plastic workpiece and a machining method of the high-frequency preheater. The high-frequency preheater comprises a high-frequency preheater body, a sealing cover arranged on the high-frequency preheater body and at least one set of lifting parts symmetrically arranged on the side face of the sealing cover. The sealing cover is arranged on the high-frequency preheater body, the rotating unit is connected with the high-frequency preheater body and located in the sealing cover, and the clamping units are arranged on the rotating unit. A group of lifting units are also symmetrically mounted on the clamping unit; according to the feeding and discharging device, the sealing cover does not need to be opened in the feeding and discharging process, meanwhile, the feeding opening and the discharging opening are fixed, an operator can complete feeding and discharging work on plastic workpieces only at a set position, meanwhile, leakage of electromagneti