Since the injection of molten resin into the die cavity is effected by the injection unit, the die closing device and the injection unit are mounted on a frame in a predetermined relationship PET preform Factory to each other. In the use of such an injection molding machine, it is often required to conduct a trial operation of the injection unit. Such a trial injection is necessary, for example, when the dies on the die closing device have been changed for the production of a different article or when the kind of the resin material is changed. After the trial injection, the operator inspects the nozzle of the injection unit for the purpose of confirmation of safe injection of the resin from the injection unit. In the conventional injection molding machine of the type described, however, this inspection takes a considerably long time and requires laborious work, because of difficulty in obtaining a large clearance between the injection unit and the die closing device, due to the fixed positional relationship between the injection unit and the die closing device. In the operation of an injection molding machine, a molten resin is injected into the die cavity between the pair of dies, after the die cavity is closed by the die closing device which usually includes a die closing cylinder. If the resin solidifies while the die cavity is closed, i.e., with the dies clamped by the die closing device, a pressure gradient is caused in the molten resin with the result that the molded article exhibits a shrink mark or deformation. In order to overcome this problem, a method known as "compression injection molding method" has been used in which, after the dies are closed by a main cylinder, a compression forming cylinder is operated to slightly open the dies and, thereafter, the molten resin is injected and the cylinders are closed again. As will be fully understood from the foregoing description, the present invention provides a vertical injection machine which is improved in such a manner as to facilitate various works such as inspection and maintenance and which can broaden the adaptability of the compression forming cylinder devices. Machineryis a plastic with many years' professional accumulated management experiences,integrated of manufacturing,R&D,technology innova-tions,sales and services.The company produce vertical injection machine,servo control,special machines and auto-matic equipments.