Feed mechanism

Claim 2

A feed mechanism for advancing a load partially at a full rate, then at a reduced rate, and then retracting the load at full rate, said mechanism comprising: (a) a fluid-pressure actuator having a cylinder carrying a piston from which a rod projects at one end, said cylinder and rod being adapted to act between a reference and the load, said cylinder having a first port at the other end and a second port communicating with said one end; (b) a 4-way valve for selecting direction of movement and having a first actuator outlet connected to said first port, a second actuator outlet, and other ports for receiving pressurized fluid and for returning fluid, said 4-way valve being disposed remotely from said cylinder; (c) flow-path control-valve means interconnecting said second port and said second actuator outlet, and having at least three selectable modes of operation respectively providing a first unrestricted flow path therethrough, a second restricted flow path therethrough, and simultaneous blockage of both said flow paths, and said control valve means including a selector valve having an inlet communicating with said second port and an outlet leading to said second restricted flow path; (d) electrical means responsive to a predetermined advance of the load for actuating said control-valve means from said first flow path mode to said second flow path mode; and (e) said control-valve means being resettable in response to a reversal of flow by said 4-way valve to reinstate said first flow path mode.

Claim 3

A feed mechanism according to claim 1, in which said electrical control-valve actuating means actuates said control-valve means into the blockage mode intermediate said first and second flow path modes.

Claim 4

A feed mechanism according to claim 1, in which said electrical control-valve actuating means is adapted to cycle said control-valve between said second flow path mode and the blockage mode.

Claim 5

A feed mechanism according to claim 1, in which said electrical control-valve actuating means includes: (a) a sensing switch responsive to the load position; (b) a first relay having a coil energizable by said sensing switch; (c) a second relay having a coil energizable by said first relay; (d) a solenoid actuator on said control valve means energized by said second relay; (e) a first timing circuit for de-energizing said second relay; and (f) a second timing circuit for reenergizing said second relay.

Claim 6

A feed mechanism according to claim 1, in which said 4-way valve has a spool which is spring-biased to a return position in which and by which load retraction and resetting of said control-valve means is effected.

Claim 7

A feed mechanism according to claim 1 in which said control-valve means includes a fluid-pressure actuated spool valve intersecting said flow paths and having two positions, each of which renders one of said paths conductive, and a throttling valve in said second flow path by which the restriction thereof is provided.

Claim 8

A feed mechanism according to claim 6 in which said control-valve means further includes a valve mechanism responsive to said electrical means and having at least one inlet communicating with said second port and three outlets, two of which lead to said first and second flow paths, and the third of which leads to an end of said spool valve when said electrical means energizes said valve mechanism.

Claim 9

A feed mechanism according to claim 7, said outlet of said selector valve leading to said second restricted flow path in bypassing relation to said electrically responsive valve.

Claim 10

A feed mechanism according to claim 6, in which one end of said spool valve is vented through a check valve to said second port and its other end is vented to said second actuator outlet.

Claim 11

A feed mechanism according to claim 1 in which said control-valve means includes: a spool valve intersecting said flow paths and having two positions, each of which renders one of said paths conductive, one end of said spool valve communicating with said second actuator outlet, and the other with said second port.

Claim 12

A feed mechanism according to claim 10, said selector valve inlet leading from said second port to a pair of alternatively closeable valve seats and also to said first unrestricted flow path, one of said valve seats leading to said second restricted flow path, and the other of said seats leading to said other end of said spool valve.

Claim 13

A feed mechanism for moving a load, comprising: (a) a fluid cylinder having a bore closed by end caps, and a piston slidable in said bore and having a rod extending through one of said caps, said rod being adapted to be connected to the load, said cylinder having a first port in the other end cap communicating with one side of said piston, and said other end cap having a second port; (b) passage means extending from the other side of said piston in said bore into said other end cap; (c) a valve assembly housed in said other end cap and connected between said passage means and said second port for controlling a flow rate of returning fluid that flows through said passage means when said first port is pressurized, said valve assembly having: (1) a pair of first and second passageways extending between said passage means and said second port; (2) a throttling valve provided between said second passageway and said second port for restricting the fluid flow through said second passageway; (3) a first fluid-pressure-actuated valve means for connecting only one of said first and second passageways at a time to said second port, said fluid-pressure-actuated valve means being movable in one direction in response to the pressure at said second port; (4) a second valve means for enabling said first passageway to communicate with said second passageway when said second passageway is connected through said throttling valve to said second port by said first valve means; and (5) said fluid-pressure-actuated valve being movable in the other direction in response to a pressure at least momentarily provided by said second valve means; and (d) means for actuating said second valve means.

Claim 14

A feed mechanism for moving a load, comprising: (a) a fluid cylinder having a bore closed by end caps, and a piston slidable in said bore and having a rod extending through one of said caps, said rod being adapted to be connected to the load, said cylinder having a first port in the other end cap communicating with one side of said piston, and said other end cap having a second port; (b) passage means extending from the other side of said piston in said bore into said other end cap; (c) a valve assembly housed in said other end cap and connected between said passage means and said second port for controlling a flow rate of returning fluid that flows through said passage means when said first port is pressurized, said valve assembly having: (1) a pair of first and second passageways extending between said passage means and said second port; (2) a throttling valve provided between said second passageway and said second port for restricting the fluid flow through said second passageway; (3) a first fluid-pressure-actuated valve means for connecting only one of said first and second passageways at a time to said second port, said fluid-pressure-actuated valve means being movable in one direction in response to the pressure at said second port; (4) a second valve means for enabling said first passageway to communicate with said second passageway when said second passageway is connected through said throttling valve to said second port by said first valve means; and (5) said fluid-pressure-actuated valve being movable in the other direction in response to a pressure at least momentarily provided by said second valve means; and (d) means for actuating said second valve means.

Claim 15

A feed mechanism according to claim 12, further comprising a selector valve having a restrictor provided between said passage means and said second passageway to control the fluid flow therethrough.

Claim 16

A feed mechanism according to claim 12, said first valve means comprising a spool valve having a bore extending across said first and second passageways and a spool slidable for axial movement in said spool valve bore between a first position in which said spool allows said first passageway to communicate with said second port and a second position in which said spool allows said second passageway to communicate with said second port, said spool valve bore having one end connected with said second port and the other end with said first passageway and said passage means through a check valve which is normally closed when said passage means is under pressure.

Claim 17

A feed mechanism according to claim 14, said second valve means comprising a poppet valve having a valve rod extending across said first and second passageways, a pair of first and second poppets on said valve rod, and a pair of first and second valve seats between said first passageway and said spool valve bore, and between said first passageway and said second passageway, respectively, said valve rod being axially movable between a first position in which said first poppet engages with said first valve seat and said second poppet disengages from said second valve seat, and a second position in which said first poppet disengages from said first valve seat and said second poppet engages with said second valve seat.

Claim 18

A feed mechanism according to claim 15, in which said actuating means comprises a solenoid mounted on said other end cap and having a ferromagnetic plate connected to said valve rod of said poppet valve.

Claim 19

A feed mechanism according to claim 16, further including an electric control circuit for energizing and de-energizing said solenoid, said circuit comprising: (a) a sensing switch responsive to the load position; (b) a first relay having a coil energizable by said sensing switch; (c) a second relay having a coil energizable by said first relay; (d) said solenoid being energizable by said second relay; (e) a first timing circuit for de-energizing said second relay; and (f) a second timing circuit for reenergizing said second relay.