Vertical injection machine having an upper die and a lower die which are adapted to be brought together in the vertical direction by the force produced by a die closing device. The injection molding machine has an injection unit 1 disposed below the lower die and is hinged through a hinge shaft to a truck movable along rails, such that the injection unit 1 is swingable vertically about the axis of the hinge shaft. The vertical swinging motion of the injection unit 1 is effected by cylinders connected to an injection head of the injection unit.

A compression forming cylinder device is provided on the lower end of each of a plurality of tie-bars which are connected between the upper die and the lower die. Each of the compression forming cylinder devices operates to urge the upper die upward away from the lower die through a pressing member, thus creating a small clearance between the upper die and the lower die when these dies are held in the closing position by the force of a die closing device.Protomold has produced a design resource that aims to give its customers a better insight into how the injection moulding process works. The Protomold Demo Mould can be dismantled to show the internal workings, features and operation of a mould.

This visualisation of the moulding process aims to inspire designs that can be produced with the least modifications and in the shortest possible time.The Protomold Demo Mould is designed in two main halves, which have been colour-coded to correspond to the two halves illustrated in a quote developed by the Protoquote system.

The A-side half creates the cavity of the part and, as there are no ejector pins to compromise the finish, this usually produces the outside or cosmetic side of the product.This half is also the side that would be fixed to the injection moulding press and is where the resin enters the mould through the sprue hole.The B-side half, often referred to as the core side, when fitted with the A-side forms the hollow centre for the resin to flow in to.

To give a complete picture, Protomold has included the injected part that is formed in the mould. Once the part is formed, it will remain on the B-side half when opened and can be removed by the ejector pin system that is also fixed to this part of the Demo Mould.

In general, an injection molding machine has a die closing device for closing a pair of dies, and an injection unit. 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 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.