초록 ▼

An injection molding apparatus capable of producing disposable wax patterns or the like and which apparatus includes a logic control and a servo-control especially designed to provide a substantially automatic molding process and to continuously monitor and to dynamically control certain variable pa

An injection molding apparatus capable of producing disposable wax patterns or the like and which apparatus includes a logic control and a servo-control especially designed to provide a substantially automatic molding process and to continuously monitor and to dynamically control certain variable parameters which are encountered during the molding process, as for example, in the present embodiment of apparatus, the control of the dynamics of fluid (wax) flow and pressure for providing substantially an automatic molding process. The servo-control is a “closed loop”servo type of control which, in the present embodiment of apparatus, continuously provides signals which relate to the fluid (wax) flow, i.e. velocity and acceleration, and fluid pressure which is then occurring in the molding cycle, and which signals are then compared with preselected input or reference signal levels whereupon a difference therebetween is then used to adjust or drive the fluid flow and pressure control systems of the apparatus toward a dynamic or balanced state which reduces this difference in signals between the input and measured signal levels to zero. The logic control for use with the molding apparatus is of the type that enables a substantially automatic molding cycle to be programmed for said apparatus whereby uniform product output is repeatedly obtained.

대표청구항 ▼

In combination, an investment pattern molding machine having a source of fluid molding material and a movable ram and a mold into which said material is to be forced under pressure by means of said movable ram moving through a predetermined distance in a fluid injection direction and thereafter retu

In combination, an investment pattern molding machine having a source of fluid molding material and a movable ram and a mold into which said material is to be forced under pressure by means of said movable ram moving through a predetermined distance in a fluid injection direction and thereafter returned to a fluid charging position, control means for initiating a molding cycle for injecting wax into said mold, a servo-control operably connected with said control means and responsive thereto to sense and control the movement of the movable ram and the pressure of said fluid molding material as generated by said movable ram forcing said material into said mold, said servo-control comprising means for actuating the movable ram and for effecting the movement thereof in a direction to initiate the injection of the fluid molding material into said mold, means operatively connected to said movable ram and to provide a first signal representative of the movement of the movable ram, means for providing a reference control signal that is representative of the movement desired for said ram in said molding cycle, means for comparing the first signal with the reference control signal and to provide a differential signal, and means for applying said differential signal to said ram actuating means effective corresponding to said differential signal to modify the movement of said ram and correspondingly regulate the injection of the fluid molding material into said mold, and means in said servo-control for limiting the quantum of the reference control signal comprising circuit means for providing a preselected maximum acceleration reference signal and a preselected maximum velocity reference signal which are representative respectively of the acceleration and velocity desired for said ram, and said servo-control having means for combining said acceleration and velocity reference signals to provide the reference control signal.