mainly used to produce piping covers in which as compared with the aforesaid embodiments of the invention only one spindle 5 is needed to install the gear inside the guide press piece 4 of the gear chain is replaced by the bearing 16 installed on the pad of moving half 2 the transmission gear 8 on the spindle 5 is engaged with the gear chain 9 the core pulling and insertion gear 6 is not engaged with the round gear shown in fig1 but changed to engage with the cone gear instead so that the linear core pulling and insertion movement is changed to be driven by the helical screw movement a piping cover manufacturing method by the device shown in fig5 is described below 1 in mold opening the stroke after unlocking the hook 11 from the hook lock 12 is preset i e setting required pipe cover demolding distance the linear length setting to position core 3 by the core lock piece 13 is changed to axial positioning by helical screw which is a common method used in the same field 2 in mold opening moving half 2 driving the core lock piece 13 travels the stoke said in step 1 to open until reaching either limit of gear rack 9 or gear chain 10 whereby the hook 11 reaches the position to start core 3 pulling 3 the moving half continue to travel until mold opening completed the demolding is completed and the piping cover is screwed out similarly after the linear length setting to position core 3 by core lock piece 13 is changed to axial positioning by helical screw the said mold push rod demolding.