The present disclosure relates to a sag compensation apparatus of a machine tool and a machine tool including the same, in which in case of sag of a cross-rail occurring due to transfer of a saddle and a ram spindle unit, hydraulic pressure compensates for the sag in real time, thereby improving machining precision and maximizing responsiveness and reliability.

A quality prediction and adaptive compensation method and apparatus for curved surface assembly are provided. The method includes: inputting a geometric error function and a thermal error function into a spatial error model, to obtain a machining error prediction model; superimposing obtained machining errors on a theoretical surface of an assembly surface, to obtain a predicted machining surface; calculating, according to an assembly median plane determined based on the assembly surface, shape errors and assembly gap errors, and predicting curved surface assembly quality of a part by using the shape errors and the assembly gap errors; calculating an adaptive compensation amount of each assembly plane of the assembly surface based on the shape errors, the assembly gap errors, and the machining errors, when the curved surface assembly quality does not meet a preset assembly quality requirement, and compensating the corresponding assembly plane by using the adaptive compensation amount.

A quality prediction and adaptive compensation method and apparatus for curved surface assembly are provided. The method includes: inputting a geometric error function and a thermal error function into a spatial error model, to obtain a machining error prediction model; superimposing obtained machining errors on a theoretical surface of an assembly surface, to obtain a predicted machining surface; calculating, according to an assembly median plane determined based on the assembly surface, shape errors and assembly gap errors, and predicting curved surface assembly quality of a part by using the shape errors and the assembly gap errors; calculating an adaptive compensation amount of each assembly plane of the assembly surface based on the shape errors, the assembly gap errors, and the machining errors, when the curved surface assembly quality does not meet a preset assembly quality requirement, and compensating the corresponding assembly plane by using the adaptive compensation amount.