For each of different resins R, a zero shear viscosity o of each resin R is obtained by using a conversion function expression whose parameters are a melt flow rate (MFR) and a set temperature of a heating cylinder and is registered. Also, a purge resin required amount Wu corresponding to a viscosity difference d between the zero shear viscosity of of a former resin Rf and the zero shear viscosity os of a succeeding resin Rs is registered. When resin switching is performed, the zero shear viscosity of of the former resin Rf and the zero shear viscosity os of the succeeding resin Rs are obtained by inputting the MFR of the former resin Rf and the MFR of the succeeding resin Rs to a molding machine controller, the viscosity difference d between the zero shear viscosity of of the former resin Rf and the zero shear viscosity os of the succeeding resin Rs is obtained, an amount of a purge resin required for resin switching is obtained as a purge resin required amount Wu, and at least the obtained purge resin required amount Wu is displayed.

There is provided a method for controlling a fluidity index of a molten resin, which can detect the fluidity of a molten resin even during successive molding operations and, in addition, can control the fluidity within a target range. The method includes: assuming that a narrow flow path, formed in a flow path for the molten resin, is a capillary or an orifice, and measuring, based on the amount of a metered molten resin and the back pressure applied to the screw during a metering step, a fluidity index which indicates the fluidity of the metered molten resin; and feeding back the measured fluidity index value and comparing it with a target value, and controlling the back pressure or the rotating speed of the screw so as to eliminate a deviation between the target value and the measured value.

There is provided a method for controlling a fluidity index of a molten resin, which can detect the fluidity of a molten resin even during successive molding operations and, in addition, can control the fluidity within a target range. The method includes: assuming that a narrow flow path, formed in a flow path for the molten resin, is a capillary or an orifice, and measuring, based on the amount of a metered molten resin and the back pressure applied to the screw during a metering step, a fluidity index which indicates the fluidity of the metered molten resin; and feeding back the measured fluidity index value and comparing it with a target value, and controlling the back pressure or the rotating speed of the screw so as to eliminate a deviation between the target value and the measured value.

An injection molding machine and a viscosity measurement method of the disclosure are provided with an injection cylinder to which a viscosity measurement unit is attachable and detachable and a control device. When setting an inner diameter of the injection cylinder or an outer diameter of the injection shaft as D. For a capillary installed to the viscosity measurement unit, a capillary inner diameter is set as d. By respectively using three or more values .sub.k of the shear rate, k being a natural number, the control device is configured to calculate injection velocities V.sub.k based on Formula (1) and automatically sets a value of the injection velocity V.sub.k within a predetermined range, among the calculated injection velocities, as an injection velocity at a time of viscosity measurement. $\left[\mathrm{Formula}\left(1\right)\right]$$\begin{array}{cc}{V}_k=\frac{d^3}{8D^2}{}_k& \left(1\right)\end{array}$

Rheological measurement systems for use with systems including pressurized polymer melts and/or other viscous materials are described. In one embodiment, a rheometer is connected to an associated system with a bent, curved, or bendable tube to permit the rheometer to measure rheological properties in locations where the rheometer could not otherwise be located due to the presence of obstructions. Embodiments including rigid straight tubes for connecting a rheometer to an associated system are also described. In another embodiment, a flow-through rheometer is connected to an industry standard -20 thermowell aperture that is typically used for attaching temperature and pressure probes to a vessel containing a viscous material such as an extruder or injection molding system.

An injection molding system includes a molding device, an inspection device configured to inspect a molded product and a control device that includes a storage unit, and a reception unit configured to receive a change content of a parameter included in a standard molding condition. The control device executes a first control of forming the molded product under a second molding condition in which the parameter is changed based on the change content, a second control of forming the molded product under a third molding condition in which the same parameter is changed, a third control of associating the second molding condition with an inspection result of the molded product formed under the second molding condition and storing the association, and a fourth control of associating the third molding condition with the inspection result of the molded product formed under the third molding condition and storing the association.

An injection molding device includes an injection device including a cylinder, a screw, and a nozzle provided at a front end of the cylinder, for discharging molten resin as the screw advances, a mold including a molded product cavity, and a resin channel between the molded product cavity and a portion abutting the nozzle, a channel pressure measuring device for acquiring channel pressure data in the resin channel, and a determination unit that determines presence/absence of clogging of a gate of the resin channel, based on features of the channel pressure data.