1. Field of the Invention
The present invention relates to the technical field of vacuum molding and cutting machines, and more particularly to a buffer assembly that buffers the impact and pressing forces produced by a cutting operation of a die cutting tool by a hydraulic element to ensure the parallelism of the cutting in order to cut a sheet uniformly and extend the service life of the die cutting tool.
2. Description of the Related Art
In recent years, pressure vacuum forming machines generally use a pair of servo cranks to drive an upper mold base and a lower mold base to improve the quality and efficiency of the forming process, and each servo crank is controlled and operated by a servomotor and connected to the corresponding upper mold base and lower mold base, and the bottom of the lower mold base has a pair of large hydraulic cylinders corresponding to the servo cranks respectively, and a small hydraulic cylinder disposed between the pair of large hydraulic cylinders, wherein the pair of large hydraulic cylinders are provided for pushing the lower mold base upward and the upper mold base downward respectively for a mold clamping of the upper and lower mold bases. After the mold clamping is completed, a sheet is primarily formed into a plurality of molded objects such as cups or other containers. The small hydraulic cylinder is to provide the travelling stability during the ascending process of the lower mold base. The finished goods still require a cutting process, so that the molded objects are separated from the sheet, and the same aforementioned driving method is used to drive a die cutting tool disposed at the upper mold base and a carrier plate of the lower mold base to be engaged to perform the cutting operation.
However, it is difficult to control the elevation stroke of the upper mold base and the lower mold base precisely (with an error of 0.01 mm) when this cutting technique is used for cutting a large sheet, the impact between the die cutting tool and the carrier plate may give rise to the issues of damaging the die cutting tool or failing to cut the desired object thoroughly. If the strokes of the carrier plate and the die cutting tool are adjusted, the force exerted onto each corner cannot be balanced and the height cannot be adjusted automatically during the mold clamping process, so that the die cutting tool and the carrier plate cannot be engaged tightly with each other, and the sheet and the molded objects cannot be cut thoroughly. In addition, the impact force produced in the mold clamping process may damage the die cutting tool or the carrier plate, so that maintenance, repair or replacement are required frequently, not only wasting time and effort, but also brining up a major problem of wasting materials. Obviously, the conventional vacuum molding and cutting machine requires improvements.