Dynamic pressure control system

Claim 2

A dynamic pressure control system particularly adapted for use in molding machines and casting machines of the type capable of operating in cycles, for controlling cavity pressure in the mold cavity of the mold of the machine during each cycle of machine operation comprising: a. sensing means supported in the mold of the machine in communication with the mold cavity and in the path of flow of material fed to the mold cavity, said sensing means sensing the movement of material in the mold cavity and transforming the movement of the material into a force signal; b. calibrating means operatively connected to said sensing means to receive said force signal therefrom, said calibrating means generating from said force signal a signal corresponding to pressure; c. comparison means connected in circuit relation with said calibrating means to receive therefrom said signal corresponding to pressure, said comparison means operating to compare said signal corresponding to pressure to a pair of predetermined pressure set points and to provide a first output in response to said signal corresponding to pressure reaching the level of one of said pair of predetermined pressure set points and a second output in response to said signal corresponding to pressure reaching the level of the other of said pair of predetermined pressure set points; d. pump means operable to cause material to be fed to the mold cavity, said pump means having a first operating condition wherein material is caused to be fed to the mold cavity at a first rate and a second operating condition wherein material is caused to be fed to the mold cavity at a second rate; and e. control means connected in circuit relation with said pump means and said comparison means, said control means in response to the receipt thereby of said first output from said comparison means when said pump means is in said first operating condition operating to alter the opeRation of said pump means to effect during the same cycle of machine operation a change in said first rate at which material is fed to the mold cavity and in response to the receipt thereby of said second output from said comparison means when said pump means is in said second operating condition operating to alter the operation of said pump means to effect during the same cycle of machine operation a change in said second rate at which material is fed to the mold cavity.

Claim 3

The dynamic pressure control system as set forth in claim 1 wherein said sensing means includes an ejector pin and a strain gauge transducer operatively connected thereto, said ejector pin is mounted in the mold for contact by the material in the mold cavity and is movable relative to the mold in response to movement of material in the mold cavity, and said strain gauge transducer is supported in the mold in contact with one end of said ejector pin and is operable to transform movement of the material in the mold cavity transmitted through said ejector pin to said strain gauge transducer into a force signal.

Claim 4

The dynamic pressure control system as set forth in claim 2 wherein said calibrating means includes a calibration control means operable to calibrate the system in accord with the sensitivity of said strain gauge transducer and switch means correlated to the size of said ejector pin to transform the force signal produced by said strain gauge transducer into a signal corresponding to pressure.

Claim 5

The dynamic pressure control system as set forth in claim 1 wherein said comparison means includes a first set point control operable for setting a predetermined high pressure set point thereon, a first comparator operatively connected to said first set point control to compare said signal corresponding to pressure to the high pressure set point on said first set point control and to provide said first output when said signal corresponding to pressure reaches the level of the high pressure set point on said first set point control, a second set point control operable for setting a predetermined dynamic pressure set point thereon, and a second comparator operatively connected to said second set point control to compare said signal corresponding to pressure to the dynamic pressure set point on said second set point control and to provide said second output when said signal corresponding to pressure reaches the level of the dynamic pressure set point on said second set point control.

Claim 6

The dynamic pressure control system as set forth in claim 4 wherein said pump means includes a booster pump, a first valve means having an open position and a closed position operatively connected to said booster pump for controlling the flow from said booster pump, a holding pump, and a second valve means having an open position and a closed position operatively connected to said holding pump for controlling the flow from said holding pump, the material being fed to the mold cavity at said first rate by said booster pump and said holding pump when said first and second valve means are both in said open position thereof, and at said second rate by said holding pump when said first valve means is in said closed position thereof and said second valve means is in said open position thereof.

Claim 7

The dynamic pressure control system as set forth in claim 5 wherein said control means includes first relay means connected in circuit relation with said first valve means and said first comparator operable for causing during the same cycle of machine operation said first valve means to move from said open position to said closed position thereof in response to said first output being provided to said first relay means from said first comparator.

Claim 8

The dynamic pressure control system as set forth in claim 6 wherein said control means further includes second relay means connected in circuit relation with said second valve means and said second comparator operable for causing during the same cycle of machine oPeration said second valve means to move from said open position to said closed position thereof in response to said second output being provided to said second relay means from said second comparator.

Claim 9

The dynamic pressure control system as set forth in claim 1 further comprising circuit means connected in circuit relation with said comparison means operable to effect a change in the setting of one of said pair of predetermined pressure set points during the succeeding cycle of machine operation in response to said signal corresponding to pressure exceeding or falling below the limits of a preestablished pressure range.

Claim 10

The dynamic pressure control system as set forth in claim 1 further comprising timer means connected in circuit relation with said comparison means and sai0 control means operable to compare the time at which said signal corresponding to pressure reaches the level of said one of said pair of predetermined pressure set points to a preestablished time and to effect during the same cycle of machine operation a change in said first rate of flow of material to the mold cavity in response to said signal corresponding to pressure reaching the level of said one of said pair of predetermined pressure set points at some time other than said preestablished time.

Claim 11

A dynamic pressure control system, particularly adapted for use in molding machines and casting machines of the type capable of operating in cycles, for controllint cavity pressure in the mold cavity of the mold of the machine during each cycle of machine operation comprising: a. sensing means supported in the mold of the machine in communication with the mold cavity and in the path of flow of material fed to the mold cavity, said sensing means sensing the movement of material in the mold cavity and transforming the movement of the material into a force signal; b. calibrating means operatively connected to said sensing means to receive said force signal therefrom, said calibrating means generating from said force signal a signal corresponding to pressure; c. comparison means connected in circuit relation with said calibrating means to receive therefrom said signal corresponding to pressure, said comparison means operating to compare said signal corresponding to pressure to a pair of predetermined pressure set points and to provide a first output in response to said signal corresponding to pressure reaching the level of one of said pair of predetermined pressure set points and a second output in response to said signal corresponding to pressure reaching the level of the other of said pair of predetermined pressure set points; d. pump means operable to cause material to be fed to the mold cavity, said pump means including a booster pump, a first valve means having an open position and a closed position operatively connected to said booster pump for controlling the flow from said booster pump, a holding pump, and a second valve means having an open position and a closed position operatively connected to said holding pump for controlling the flow from said holding pump, the material being fed to the mold cavity at a first rate by said booster pump and said holding pump when said first and second valve means are both in said first position thereof and at a second rate by said holding pump when said first valve means is in said closed position thereof and said second valve means is in said open position thereof; and e. control means connected in circuit relation with said pump means and said comparison means, said control means in response to the receipt thereby of said first output from said comparison means when said first valve means is in said open position thereof operating to cause said first valve means to move to said closed position thereof to effect during the same cycle of machine operation a change in said first rate at which material is fed to the mold cavity and in response to the receipt thereby of said second output from said comparison means when said second valve means is in said open position thereof operating to cause said second valve means to move to said closed position thereof to effect during the same cycle of machine operation a change in said second rate at which material is fed to the mold cavity.

Claim 12

A dynamic pressure control system, particularly adapted for use in molding machines and casting machines of the type capable of operating in cycles, for controllint cavity pressure in the mold cavity of the mold of the machine during each cycle of machine operation comprising: a. sensing means supported in the mold of the machine in communication with the mold cavity and in the path of flow of material fed to the mold cavity, said sensing means sensing the movement of material in the mold cavity and transforming the movement of the material into a force signal; b. calibrating means operatively connected to said sensing means to receive said force signal therefrom, said calibrating means generating from said force signal a signal corresponding to pressure; c. comparison means connected in circuit relation with said calibrating means to receive therefrom said signal corresponding to pressure, said comparison means operating to compare said signal corresponding to pressure to a pair of predetermined pressure set points and to provide a first output in response to said signal corresponding to pressure reaching the level of one of said pair of predetermined pressure set points and a second output in response to said signal corresponding to pressure reaching the level of the other of said pair of predetermined pressure set points; d. pump means operable to cause material to be fed to the mold cavity, said pump means including a booster pump, a first valve means having an open position and a closed position operatively connected to said booster pump for controlling the flow from said booster pump, a holding pump, and a second valve means having an open position and a closed position operatively connected to said holding pump for controlling the flow from said holding pump, the material being fed to the mold cavity at a first rate by said booster pump and said holding pump when said first and second valve means are both in said first position thereof and at a second rate by said holding pump when said first valve means is in said closed position thereof and said second valve means is in said open position thereof; and e. control means connected in circuit relation with said pump means and said comparison means, said control means in response to the receipt thereby of said first output from said comparison means when said first valve means is in said open position thereof operating to cause said first valve means to move to said closed position thereof to effect during the same cycle of machine operation a change in said first rate at which material is fed to the mold cavity and in response to the receipt thereby of said second output from said comparison means when said second valve means is in said open position thereof operating to cause said second valve means to move to said closed position thereof to effect during the same cycle of machine operation a change in said second rate at which material is fed to the mold cavity.

Claim 13

The dynamic pressure control system as set forth in claim 10 wherein said first valve means comprises a first operated valve and a first solenoid.

Claim 14

The dynamic pressure control system as set forth in claim 11 wherein said second valve means comprises a second operated valve and a second solenoid.

Claim 15

The dynamic pressure control system as set forth in claim 10 wherein said comparison means includes a first set point control operable for setting a predetermined high pressure set point thereon, a first comparator operatively connected to said first set point control to compare said signal corresponding to pressure to the high pressure set point on said first set point control and to provide said first output when said signal corresponding to pressure reaches the level of the high pressure set point on said first set point control, a second set point control operable for setting a predetermined dynamic pressure set point thereon, and a second comparator operatively connected to said second set point control to compare said signal corresponding to pressure to the dynamic pressure set point on said second set point control and to provide said second output when said signal corresponding to pressure reaches the level of the dynamic pressure set point on said second set point control.