Press-type strapping machine with platen-locking system
A press-type strapping machine with a platen-locking system is provided. When the platen-locking system is in a locked configuration, it prevents the platen from descending regardless of its vertical position. The strapping machine includes a machine frame; a load supporter configured to support and move the load; a platen configured to compress the load against the load supporter; and a platen-locking system including a ratchet wheel, a locking arm, and an actuator operably connected to the locking arm and configured to move the locking arm relative to the ratchet wheel from a locked position to an unlocked position. When the locking arm is in the locked position, the locking arm engages the ratchet wheel in a manner that prevents the platen from descending. When the locking arm is in the unlocked position, the locking arm is disengaged from the ratchet wheel such that the platen can descend.
1 . A strapping machine comprising:
a machine frame;
a load supporter;
a platen supported by the machine frame and movable toward and away from the load supporter;
a platen actuator operably connected to the platen and configured to move the platen toward and away from the load supporter;
a platen-locking system having a locked configuration in which the platen-locking system prevents the platen from moving toward the load supporter and an unlocked configuration in which the platen-locking system does not prevent the platen from moving toward the load supporter, wherein the platen-locking system comprises a locking arm movable between a first position and a second position, wherein the platen-locking system is in the locked configuration when the locking arm is in the first position and in the unlocked configuration when the locking arm is in the second position;
a strapping head; and
a controller configured to, responsive to receiving a platen-unlock instruction when the locking arm is in the first position, switch the platen-locking system from the locked configuration to the unlocked configuration by:
controlling the platen actuator to begin moving the platen away from the load supporter; and
after the platen begins moving away from the load supporter, controlling the platen-locking system to move the locking arm from the first position to the second position.
2 . The strapping machine of claim 1 , wherein the platen comprises a platen frame and a drive shaft rotatable relative to the platen frame, wherein the drive shaft is configured such that rotation of the drive shaft in a raising rotational direction causes the platen to ascend and rotation of the drive shaft in a lowering rotational direction causes the platen to descend, wherein the platen actuator is operably connected to the drive shaft to rotate the drive shaft in the raising and lowering rotational directions, wherein the platen actuator is separate from the platen-locking system.
3 . The strapping machine of claim 2 , wherein the machine frame comprises first and second legs comprising first and second toothed racks, wherein the drive shaft comprises first and second pinions rotatable with the drive shaft, wherein the first pinion is meshed with the first toothed rack and the second pinion is meshed with the second toothed rack.
4 . The strapping machine of claim 1 , wherein the controller is operably connected to the locking arm and configured to cause the locking arm to move from the first position to the second position.
5 . The strapping machine of claim 4 , wherein the platen-locking system further comprises a locking-arm actuator operably connected to the locking arm to move the locking arm from the first position to the second position, wherein the controller is operably connected to the locking-arm actuator and configured to control the locking-arm actuator.
6 . The strapping machine of claim 5 , wherein the platen-locking system further comprises a ratchet wheel mounted to and rotatable with the drive shaft, wherein when the locking arm is in the first position, the locking arm engages the ratchet wheel and prevents the ratchet wheel and the drive shaft from rotating in the lowering rotational direction, wherein when the locking arm is in the second position, the locking arm is disengaged from the ratchet wheel such that the ratchet wheel and the drive shaft are rotatable in the lowering rotational direction.
7 . The strapping machine of claim 6 , wherein the ratchet wheel comprises a body including multiple radially extending teeth, wherein the locking arm is positioned so the locking arm engages at least one of the teeth when in the first position.
8 . The strapping machine of claim 7 , wherein the teeth are curved in the lowering rotational direction.
9 . The strapping machine of claim 8 , wherein a pocket is formed between each pair of adjacent teeth, wherein the locking arm further comprises a locking finger, wherein the locking finger is received in one of the pockets when the first arm is in the first position.
10 . The strapping machine of claim 9 , wherein the locking arm is pivotable between the first and second positions.
11 . The strapping machine of claim 6 , further comprising an actuator-control system, wherein the controller is operably connected to the locking-arm actuator via the actuator-control system.
12 . The strapping machine of claim 11 , wherein the locking-arm actuator comprises a pneumatic cylinder, wherein the actuator-control system comprises a pneumatic circuit.
13 . The strapping machine of claim 12 , wherein the pneumatic circuit comprises:
a pressurized air source;
a control valve in fluid communication with the pressurized air source and configured to selectively direct pressurized air from the pressurized air source to the locking-arm actuator; and
a pressure-relief valve in fluid communication with and between the pressurized air source and the control valve, wherein the pressure-relief valve has:
a routing configuration in which the pressure-relief valve directs pressurized air from the pressurized air source to the control valve, and
a venting configuration in which the pressure-relief valve prevents pressurized air from flowing from the pressurized air source to the control valve and enables pressurized air to vent from the locking-arm actuator to depressurize the locking-arm actuator.
14 . The strapping machine of claim 13 , wherein the pneumatic circuit further comprises a compressor configured to generate pressurized air, wherein the pressurized air source comprises an accumulator in fluid communication with the compressor and configured to store pressurized air received from the compressor.
15 . The strapping machine of claim 14 , further comprising a pressure sensor configured to sense the pressure of the pressurized air within the accumulator, wherein the compressor is configured to generate and send pressurized air to the accumulator when the pressure of the pressurized air within the accumulator is below a target pressure.
16 . The strapping machine of claim 13 , wherein the controller is operably connected to the control valve and configured to open and close the control valve to selectively direct pressurized air to the locking-arm actuator, wherein the controller is operably connected to the pressure-relief valve and configured to switch the pressure-relief valve between its routing and venting configurations.
17 . The strapping machine of claim 16 , further comprising an emergency stop actuator communicatively connected to the controller, wherein the controller is configured to, when the emergency stop actuator is actuated and the locking-arm actuator is pressurized, control the pressure-relief valve to switch from its routing configuration to its venting configuration to depressurize the locking-arm actuator.
18 . The strapping machine of claim 16 , wherein the controller is configured to, responsive to receiving a platen-lock instruction when the locking-arm actuator is in the second position:
control the control valve to pressurize the locking-arm actuator to move the locking arm toward the first position and into contact with the ratchet wheel; and
control the platen actuator to rotate the drive shaft and the ratchet wheel in the lowering rotational direction until the locking arm engages the ratchet wheel and prevents further rotation in the lowering rotational direction.
19 . The strapping machine of claim 18 , wherein the locking-arm actuator includes a double-acting pneumatic cylinder, wherein the control valve is configured to selectively pressurize the locking-arm actuator to move the locking arm between its first and second positions.
20 . The strapping machine of claim 1 , wherein the controller is further configured to, responsive to receiving a platen-lock instruction when the locking arm is in the second position, switch the platen-locking system from the unlocked configuration to the locked configuration by:
controlling the platen-locking system to move the locking arm from the second position to the first position; and
controlling the platen actuator to begin moving the platen toward the load supporter until the locking arm prevents the platen from descending.