Question

Application: A plastic thermo-forming machine is capable of heating and forming parts of various thicknesses. The parts must be held in their molded positions while the plastic is curing in its final form. The length of time needed to cure the plastic will vary depending on the thickness. This in turn will require a forming operation that has a variable time delay before the part is automatically released. Objective: To be able to design and assemble a “LIMITED MEMORY” circuit. Circuit Problem: Using the given components and layout, design a schematic circuit which will extend a cylinder for an adjustable period of time, then automatically retract the cylinder. Design and draw schematic diagram. Approved: Connect components to match schematic diagram. Operate and explain circuit to instructor. Approved: Layout of Components Needed: Part # Qty go 2 3 4 5 Component Description 2-position, spring offset, 3-way valve volume chamber air pilot actuator flow control valve push button actuator single acting, spring retum cylinder NOTE: ACTUATORS MAY ALREADY BE ASSEMBLED ON A VALVE.

Answer 1

Explaination:

• To start the circuit we have 3/2DCV(1) which is push button (5)operated with spring return. When we push the push button(5) the DCV(1) get actuated and comes at its 1st position and allow the air to flow towards the volume chamber(2) through the FCV(4) by which we can control the speed of the flow of air.
• When the volume chamber (2) is totally filled then the air start flowing towards the 3/2DCV(1)which is air pilot (3)operated and spring return which get actuated to 1st position due to the air pilot signal, then the air starts flowing towards the single acting cylinder(6) with spring return and start performing extension motion.
• When we relase the push button(5) the DCV(1) comes to second position and not allow the air to flow in circuit due to which the DCV(1) which is air pilot comes to 2nd position as air pilot doesn't give signal. Finally the cylinder (6)perform retraction motion due to spring force which is present inside it.
• The volume chamber (2)is used for time delay. When the DCV (1) which is push button (5) operated doesn't allow air to flow still the air pilot(3) keep the DCV(1) at actuated position because of volume chamber(2) which store air and when circuit get off due to spring force or any gas pressure it gives air pilot signal (3) to the DCV(1).