Electrohydraulic ram velocity control circuit

Claim 2

In conjunction with a die having a cavity therein, a shot cylinder, means for feeding fluid into the shot cylinder and for passing fluid out of the shot cylinder into the die cavity, a ram for forcing the fluid from the shot cylinder into the die cavity and means for driving the ram into the shot cylinder, the improvement comprising means for sensing the position of the ram in the shot cylinder over substantially the entire length of the shot cylinder and means operable in response to the sensed position of the ram for controlling the movement of the ram into the shot cylinder over substantially the entire length of the shot cylinder to provide optimum fluid flow from the shot cylinder into the die cavity during filling of the die cavity.

Claim 3

Structure as set forth in claim 1 wherein the means for sensing the position of the ram comprises a pulse generator for producing a seParate pulse in response to arrival of the ram at a plurality of predetermined positions within the shot cylinder which positions are spaced apart over substantially the entire length of the shot cylinder.

Claim 4

Structure as set forth in claim 1 wherein the means for controlling the driving of the ram comprises a multiple slidewire resistance circuit for providing different electric output signals and a switching circuit connected to the multiple slidewire resistance circuit for passing separate ones of the different electric output signals in response to different sensed positions of the ram.

Claim 5

Structure as set forth in claim 3 wherein the means for controlling the driving of the ram further includes a main hydraulic valve controlling flow of hydraulic fluid to the ram.

Claim 6

Structure as set forth in claim 4 and further including means for controlling the driving of the ram into the cylinder in accordance with at least one of the additional parameters velocity of a portion of the main hydraulic valve, the pressure of the fluid in the shot cylinder, the velocity of the ram, and the pressure of the fluid in the die cavity.

Claim 7

Structure as set forth in claim 5 wherein the means for controlling the driving of the ram further includes a pilot electrohydraulic servo valve positioned between the switching circuit and main hydraulic valve for controlling fluid flow through the main hydraulic valve.

Claim 8

In combination, a die cavity, a shot cylinder into which molten metal is placed for movement into the die cavity positioned adjacent to the die cavity, a reciprocally movable ram positioned within the shot cylinder for moving the molten metal from the shot cylinder into the die cavity in accordance with the movement of the ram into the shot cylinder, a ram cylinder in which the ram is mounted for reciprocal movement, a main hydraulic valve connected to the ram cylinder operable to produce movement of the ram within the ram cylinder and shot cylinder, an electrohydraulic servo valve connected to the main hydraulic valve for metering hydraulic fluid through the main hydraulic valve in accordance with an electric signal applied to the servo valve, a source of electrical energy, a multiple slidewire resistance circuit connected to the source of electrical energy for providing a plurality of different output electrical signals, a switching circuit connected to the multiple slidewire resistance circuit for providing an output from the switching circuit in accordance with one of the output signals of the multiple slidewire resistance circuit in accordance with programming of the switching circuit, means for sensing the position of the ram and programming the switching circuit in accordance with the position of the ram whereby the output signal from the switching circuit reflects the position of the ram, means connected to the switching circuit for modifying the output signal from the switching circuit in accordance with at least one of the pressure in the shot cylinder, the velocity of the ram, and the pressure in the die cavity to provide a modified output signal, means for further modifying the modified output signal in accordance with the position of the main hydraulic valve and means for actuating the electrohydraulic servo valve with the further modified output signal whereby the placing of the molten metal in the die cavity is accomplished under optimum conditions.

Claim 9

In combination, a die cavity, a shot cylinder into which molten metal is placed for movement into the die cavity positioned adjacent to the die cavity, a reciprocally movable ram positioned within the shot cylinder for moving the molten metal from the shot cylinder into the die cavity in accordance with the movement of the ram into the shot cylinder, a ram cylinder in which the ram is mounted for reciprocal movement, a main hydraulic valve connected to the ram cylinder operable to produce movement of the ram within the ram cylinder and shot cylinder, an electrohydraulic servo valve connected to the main hydraulic valve for metering hydraulic fluid through the main hydraulic valve in accordance with an electric signal applied to the servo valve, a source of electrical energy, a multiple slidewire resistance circuit connected to the source of electrical energy for providing a plurality of different output electrical signals, a switching circuit connected to the multiple slidewire resistance circuit for providing an output from the switching circuit in accordance with one of the output signals of the multiple slidewire resistance circuit in accordance with programming of the switching circuit, means for sensing the position of the ram and programming the switching circuit in accordance with the position of the ram whereby the output signal from the switching circuit reflects the position of the ram, means connected to the switching circuit for modifying the output signal from the switching circuit in accordance with at least one of the pressure in the shot cylinder, the velocity of the ram, and the pressure in the die cavity to provide a modified output signal, means for further modifying the modified output signal in accordance with the position of the main hydraulic valve and means for actuating the electrohydraulic servo valve with the further modified output signal whereby the placing of the molten metal in the die cavity is accomplished under optimum conditions.