Squeeze pin circuit for die casting and hydraulic unit

1. A squeeze pin circuit for die casting installed to a direction switching valve, the direction switching valve being configured to switch a direction of hydraulic pressure to a core cylinder, the squeeze pin circuit being configured to drive a squeeze pin, the squeeze pin being configured to partially pressurize molten metal filled in a cavity, the squeeze pin circuit comprising:

a squeeze pin cylinder and the core cylinder coupled to the direction switching valve to drive the squeeze pin and a core; and

a flow rate adjusting unit installed on a hydraulic pressure path, the hydraulic pressure path coupling the direction switching valve to a head side of the squeeze pin cylinder, the flow rate adjusting unit being configured to ensure pressure compensation and temperature compensation.

2. The squeeze pin circuit for die casting according to claim 1 , wherein

the flow rate adjusting unit includes a check valve configured to allow a hydraulic pressure in a direction heading for the direction switching valve in the hydraulic pressure path.

3. The squeeze pin circuit for die casting according to claim 1 , wherein

the flow rate adjusting unit is configured to ensure displaying a degree of opening in the hydraulic pressure path in digital.

4. The squeeze pin circuit for die casting according to claim 1 , wherein

the hydraulic pressure path is coupled parallel to a hydraulic pressure path at one side of the core cylinder, a hydraulic pressure path coupling the direction switching valve to a rod side of the squeeze pin cylinder being coupled parallel to a hydraulic pressure path at another side of the core cylinder.

5. The squeeze pin circuit for die casting according to claim 1 , wherein

a plurality of squeeze pin cylinders and a plurality of flow rate adjusting units are coupled parallel to the direction switching valve.

6. The squeeze pin circuit for die casting according to claim 5 , further comprising

an accumulator circuit configured to accumulate a hydraulic pressure from a hydraulic pressure source that supplies the direction switching valve with a hydraulic pressure, the accumulator circuit being configured to supply the hydraulic pressure to hydraulic pressure paths on primary sides of the flow rate adjusting units.

7. A hydraulic unit that includes the squeeze pin circuit for die casting according to claim 1 , comprising

a block to which the flow rate adjusting unit is installed, the block including a hydraulic pressure path at a primary side of the flow rate adjusting unit, wherein

the block includes a bus line coupled to the hydraulic pressure path on the primary side, the bus line penetrating the block.

8. The hydraulic unit according to claim 7 , further comprising:

a limit switch configured to output a signal indicative of the squeeze pin being at a position before feeding, the limit switch being configured to output a signal indicative of the squeeze pin being at a position after the feeding; and

time measurement means installed to the block, the time measurement means being configured to measure an operating time of the squeeze pin based on the signal output from the limit switch.

9. The hydraulic unit according to claim 7 , wherein

pressure measurement means is installed to the block, the pressure measurement means being configured to measure a hydraulic pressure inside the bus line.

10. The hydraulic unit according to claim 7 , wherein

the block is installed to a mold to which the squeeze pin is installed, the squeeze pin being driven by the squeeze pin circuit.

11. The hydraulic unit according to claim 10 , wherein:

in a case where a plurality of flow rate adjusting units are installed to the block, the block is installed to the mold in a vertically-elongated state, and

the flow rate adjusting units are installed to the block to be arranged in the vertically-elongated direction.