Valve pin rotation limiter

Method of limiting or preventing rotation of a valve pin in an injection molding apparatus comprising an injection machine that injects a heated fluid material through an upstream end of a fluid delivery channel towards a downstream end of the fluid delivery channel towards a gate to a cavity of a mold, the method comprising:

• providing an elongated valve pin having a longitudinal axis and a proximal end interconnected the proximal end of the valve pin to an actuator that is controllably drivable to move the pin back and forth along its longitudinal axis between one or more upstream axial positions and one or more downstream axial positions;
• providing an elongated rail having a rail axis, the rail being stationarily mounted relative to the actuator such that the rail axis is radially spaced apart from the longitudinal axis of the valve pin;
• providing a finger projecting between the rail and the valve pin, the finger having a first end mounted on or to one of the rail or the valve pin and a second end slidably engaged against a receiving surface of the other of the rail or the valve pin;
• the second end of the finger and the receiving surface against which the second end of the finger is engaged being adapted to resist or prevent rotation of the valve pin around the axis of the valve pin;
• and
• moving the valve pin between upstream and downstream positions while the second end of the finger and receiving surface engage each other to resist or prevent rotation of the valve pin.

Apparatus for limiting rotation of a valve pin in an injection molding system comprised of an injection machine and a fluid distribution system that injects a heated fluid material through an upstream end of a fluid delivery channel towards a downstream end of the fluid delivery channel towards a gate to a cavity of a mold, the apparatus comprising:

• an elongated valve pin having a longitudinal axis and a proximal end interconnected to an actuator that is controllably drivable to move the pin back and forth along its longitudinal axis between one or more upstream axial positions and one or more downstream axial positions;
• an elongated rail having a rail axis, the rail being stationarily mounted relative to the actuator such that the rail axis is radially spaced apart from the axis of the valve pin;
• a finger projecting between the rail and the valve pin, the finger having a first end mounted on or to one of the rail or the valve pin and a second end slidably engaged against a receiving surface of the other of the rail or the valve pin;
• wherein the second end of the finger and the receiving surface against which the second end of the finger is engaged are adapted to resist or prevent rotation of the valve pin around the axis of the valve pin.

An injection molding system comprising:

• an injection machine and a fluid distribution system that injects a heated fluid material through an upstream end of a fluid delivery channel towards a downstream end of the fluid delivery channel towards a gate to a cavity of a mold;
• an elongated valve pin having a longitudinal axis and a proximal end interconnected to an actuator comprised of an electric motor having a shaft that is controllably drivable to move the pin back and forth along its longitudinal axis between one or more upstream axial positions and one or more downstream axial positions;
• an elongated rail having a rail axis, the rail being stationarily mounted relative to the actuator such that the rail axis is radially spaced apart from the axis of the valve pin;
• a finger projecting between the rail and the valve pin, the finger having a first end mounted on or to one of the rail or the valve pin and a second end slidably engaged against a receiving surface of the other of the rail or the valve pin;
• wherein the second end of the finger and the receiving surface against which the second end of the finger is engaged are adapted to resist or prevent rotation of the valve pin around the axis of the valve pin.