Injection molding flow control apparatus and method

• US 9,498,909 B2
• Filed: 06/23/2014
• Issued: 11/22/2016
• Est. Priority Date: 11/23/2011
• Status: Active Grant

• Current Assignee: Synventive Molding Solutions Incorporated
• Original Assignee: Synventive Molding Solutions Incorporated
• Inventors: Moss, Mark, Galati, Vito
• Primary Examiner(s): SANDERS, JAMES M
• Application Number:
  US14/311,785
• Publication Number:
  US 20140300019A1
• Time in Patent Office: 883 Days
• US Class Current: 1/1
• CPC Class Codes: B29C 2045/1792 Machine parts driven by an electric motor, e.g. electric servomotor
• CPC Class Codes: B29C 2045/2712 Serial gates for moulding articles in successively filled serial mould cavities
• CPC Class Codes: B29C 2045/2865 having position detecting means
• CPC Class Codes: B29C 2045/2872 with at least three positions, e.g. two different open positions to control the melt flow
• CPC Class Codes: B29C 2945/76076 duration
• CPC Class Codes: B29C 2945/76083 Position
• CPC Class Codes: B29C 2945/76277 nozzles
• CPC Class Codes: B29C 2945/76381 Injection
• CPC Class Codes: B29C 2945/76568 Position
• CPC Class Codes: B29C 2945/76598 linear movement
• CPC Class Codes: B29C 2945/76755 nozzles
• CPC Class Codes: B29C 2945/76859 Injection
• CPC Class Codes: B29C 2945/76933 The operating conditions are corrected immediately, during the same phase or cycle
• CPC Class Codes: B29C 45/03 Injection moulding apparatus transfer moulding B29C45/02
• CPC Class Codes: B29C 45/2703 Means for controlling the runner flow, e.g. runner switches, adjustable runners or gates
• CPC Class Codes: B29C 45/281 Drive means therefor
• CPC Class Codes: B29C 45/80 of relative position of mould parts
• CPC Class Codes: B29K 2105/0067 Melt

Abstract

A method and apparatus for performing an injection molding cycle comprising drivably interconnecting a valve pin to an electric motor actuator and controllably operating the electric motor to drive the valve pin at one or more reduced rates of upstream or downstream travel based on either detection of the position of the pin or actuator or on a preselected length of time at which to drive the valve pin.

Claims

1. A method of performing an injection molding cycle in an injection molding apparatus comprising a manifold that receives an injection fluid, the manifold distributing injection fluid to a fluid delivery channel that delivers the injection fluid under an injection pressure to a gate of a mold cavity and a valve pin having an axis and a tip end, the valve pin being slidably mounted for movement along the axis within the fluid delivery channel, the method comprising:

drivably interconnecting the valve pin to an electric motor driven by a source of electrical power or energy in an arrangement wherein the electric motor drives the valve pin along the axis and drives the tip end of the valve pin between a first position where the tip end of the valve pin obstructs the gate to prevent the injection fluid from flowing into the cavity, a second position upstream of the first position wherein the tip end of the valve pin restricts flow of the injection fluid along at least a portion of the length of the drive path extending between the first position and the second position, and a third maximum upstream position where the injection fluid material flows freely without restriction from the tip end of the pin through the first gate, the electric motor being electrically operable to drive the valve pin at one or more intermediate rates of upstream and downstream travel extending between zero and a maximum rate of upstream travel and a maximum rate of downstream travel,

selecting a length of travel between the third maximum upstream position and a predetermined third position that is downstream of the maximum upstream position and upstream of the first position,

controllably operating the electric motor to drive the valve pin at one or more high rates of downstream travel that are equal to or less than the maximum rate of downstream travel when the valve pin is disposed at the third maximum upstream position during the course of an injection cycle,

sensing the position of the valve pin to determine when the tip end of the valve pin has reached the preselected third position during the course of downstream travel,

controllably operating the motor to drive the valve pin at one or more intermediate rates of downstream travel that are less than the one or more high rates of downstream travel when the tip end of the valve pin has been determined in the step of sensing to have reached the third position to drive the tip end of the valve pin downstream from the third position to the first position.

2. The method of claim 1 wherein the one or more high rates of downstream travel are equal to the maximum rate of downstream travel.

3. The method of claim 1 further comprising:

beginning the injection molding cycle from the first position,

controllably operating the motor to drive the valve pin at one or more of the intermediate upstream rates of travel over the length of the path of upstream travel between the first position and the second position,

sensing the position of the valve pin to determine when the tip end of the valve pin has reached the second position during the course of upstream travel,

controllably operating the motor to drive the valve pin upstream from the second position to the maximum upstream position at one or more high upstream rates of travel that are greater than the intermediate upstream rates of travel.

4. The method of claim 3 wherein the motor is controllably operated to drive the valve pin continuously upstream from the second position to the maximum upstream position at the maximum rate of upstream travel.

5. An injection molding apparatus comprising a manifold that receives an injection fluid, the manifold distributing injection fluid to a fluid delivery channel that delivers the injection fluid under an injection pressure to a gate of a mold cavity and a valve pin having an axis and a tip end, the valve pin being slidably mounted for movement along the axis within the fluid delivery channel, the apparatus comprising:

an electric motor driven by a source of electrical power or energy, the electric motor being drivably interconnected to the valve pin in an arrangement wherein the electric motor drives the valve pin along the axis and drives the tip end of the valve pin between a first position where the tip end of the valve pin obstructs the gate to prevent the injection fluid from flowing into the cavity, a second position upstream of the first position wherein the tip end of the valve pin restricts flow of the injection fluid along at least a portion of the length of the drive path extending between the first position and the second position, and a third maximum upstream position where the injection fluid material flows freely without restriction from the tip end of the pin through the first gate, the electric motor being electrically operable to drive the valve pin at one or more intermediate rates of upstream and downstream travel extending between zero and a maximum rate of upstream travel and a maximum rate of downstream travel,

a controller containing instructions that controllably operates the electric motor to drive the valve pin at one or more high rates of downstream travel that are equal to or less than the maximum rate of downstream travel when the valve pin is disposed at the third maximum upstream position during the course of an injection cycle,

a sensor for sensing the position of the valve pin to determine when the tip end of the valve pin has reached a predetermined third position downstream of the maximum upstream position and upstream of the first position during the course of downstream travel,

the controller including instructions that controllably operate the motor to drive the valve pin at one or more intermediate rates of downstream travel that are less than the one or more high rates of downstream travel to drive the tip end of the valve pin downstream from the third position to the first position when the tip end of the valve pin has been determined in the step of sensing to have reached the third position.

6. The apparatus of claim 5 wherein the one or more high rates of downstream travel are equal to the maximum rate of downstream travel.

7. The apparatus of claim 5 wherein the controller includes instructions that controllably operate the motor to drive the valve pin beginning from the first position at one or more of the intermediate upstream rates of travel between the first position and the second position,

the sensor sensing the position of the valve pin to determine when the tip end of the valve pin has reached the second position during the course of upstream travel,

the controller including instructions to controllably operate the motor to drive the valve pin upstream from the second position to the maximum upstream position at one or more high upstream rates of travel that are greater than the intermediate upstream rates of travel.

8. The apparatus of claim 7 wherein the controller includes instructions to controllably operate the motor to drive the valve pin continuously upstream from the second position to the maximum upstream position at the maximum rate of upstream travel.

9. The apparatus of claim 7 wherein the controller includes instructions to controllably operate the motor to drive the valve pin continuously upstream beginning from the first position at one or more of the intermediate upstream rates of travel over the entire length of travel of the valve pin from the first position to the maximum upstream position.