Service Home Pallet Changer - Troubleshooting Guide - NGC
Last updated: 01/27/2022

Pallet Changer - Troubleshooting Guide - NGC

Introduction

Use this troubleshooting guide to find and correct problems with the Hydraulic Pallet Changer.

Pallet Change Sequence

  1. Check that pallet is clamped to the receiver.
  2. Move the Z-axis and B-axis to zero position.
  3. Unclamp the pallet.
  4. Using hydraulic pressure the H-frame is lifted, rotated and lowered.
    Note: The air blast is on while the pallet is rotating. Air pressure is monitored by the air pressure system.
  5. The pallet is clamped to the receiver.

When a pallet change occurs, a request for hydraulic demand is sent to the HPU.  The HPU will monitor hydraulic pressure during the pallet change.  The pallet change is not permitted to advance if hydraulic pressure is insufficient. If the pressure is absent for a parameterized time period, an alarm is generated. 

Settings:

  • 216 Servo and Hydraulic Shutoff
  • 382 Disable Pallet Changer

Pallet Changer - Bottom View

  1. Full CCW sensor
  2. Full CW sensor
  3. H-Frame (Pallet) Up Sensor
  4. H-Frame (Pallet) Down Sensor
  5. Rack
  6. Hydraulic Cylinder (CW/CCW)
  7. H-Frame Lift Cylinder
  8. Lock Station Handle
  9. Rack Stop Adjustment Screw
Fourth Axis Receiver - Side View
 
  1. 4th Axis Receiver
  2. 4th Axis Home Sensor
  3. Hydraulic Clamp/Unclamp Input 
  4. Air Blast Input 
  5. Pallet Unclamp Sensor
  6. Pallet Clamp Sensor

Symptoms

Symptom Possible Cause Corrective Action
Alarm 644 APC Low Air Pressure The air pressure is low during a pallet change. Check for air leaks and air pressure on the lube cabinet.
Alarm 945 APC Pallet Lower Timeout The H-frame down sensor was not contacted before the timeout period. Check the H-Frame down sensor to make sure it changes states.
Alarm 956 APC Lift Frame Up Timeout The H-frame up sensor was not contacted before the timeout period. Check the H-Frame up sensor to make sure it changes states.
Alarm 9114 H-Frame Rotate Timeout The CW/CCW solenoids are not actuating. Check that the CW/CCW solenoids are getting 115 VAC from the I/O PCB.
Alarm 9115 APC Illegal Switch Condition Rotate Frame The H-Frame CW/CCW inputs are in a invalid state during a Pallet Change. Make sure the H-frame CW/CCW inputs are changing to the correct states.  Look at the H-Frame CW/CCW I/O status section below.
Alarm 9116 APC Pallet is Unclamped The pallet clamp/unclamp inputs are in a invalid state.
 Make sure the pallet clamp/unclamp inputs are changing to the correct states.  Look at the Clamp/Unclamp I/O section below.
Pallet lowers before reaching clamp position. Switch position is not correct.  Adjust the switch/bracket. If there is not enough adjustment, the gear rack was changed to have a notch added so it would not trip the sensor before the pallet was in place. The switch mount block was also changed to a shorter length. Replace the gear rack and switch mount block with the new version. Check to see what version you have before ordering replacement part. 
Pallet cylinder damper is not slowing the pallet, causing it to slam into the hard stop. Damper adjustment or switch adjustment is not correct. Adjust the damper on the cylinder. Counter clockwise on the screw to open and speed up the damper. Clockwise to close and slow it down. It may be closed or clogged and needs to be open more to clear it out. 
Recovery Required Message keeps appearing on the screen after a pallet change. The H-Frame (Pallet Changer) at Full CW/CCW sensor are loose. Make sure the H-Frame (Pallet Changer) at Full CW/CCW sensors are working and they are correctly fasten.  See H Frame Rotate CW/CCW I/O Status section below.
Minimal air coming out of air blast manifold  Debris entering the air blast assembly New version of air blast manifold (20-7437A) has a shaft seal (57-0813) to prevent debris from entering the assembly. See Air Blast Manifold Seal Section for further detail. 
Pallet Changer Clamp/Unclamp mechanism operates in reverse. The hydrualic lines are reversed. Check at both ends of the hydrualic lift cylinder and hydraulic power unit and verify that they are set correctly.
The pallet clamp/unclamp sensors are reversed. With a Pallet on the receiver.  Command the pallet to clamp and unclamp.  Go to I/O tab and verify that inputs 25 PALLET CHANGER PALLET UNCLMPED and 29 PALLET CHANGER PALLET CLAMPED toggle to the correct state.  Check the terminal block, check that they are connected correctly.

Clamp/Unclamp I/O Status

Machine State

Pallet UnClamp

Input #25 

Pallet Clamp

Input #29

Pallet Clamp

Output # 44
Pallet is on the workstation and clamped 0 1 0
Pallet is on the workstation and unclamped 1 0 1
No pallet on the work station and clamped 0 0 0

H-Frame Up/Down I/O Status

Machine State

H-Frame (Pallet Changer) DOWN

Input #23

H-Frame (Pallet Changer) UP

Input #35

H-Frame (Pallet Changer) UP

Output # 48

H-Frame (Pallet Changer) DOWN

Output# 165
Pallet is on the workstation and the H-frame is DOWN 1 0 0 1
Pallet is on the workstation and the H-frame is UP 0 1 1 0

H-Frame Rotate CW/CCW I/O Status

Machine State

H-Frame (Pallet Changer) at Full CCW

Input #163

H-Frame (Pallet Changer) at Full CW

Input #164

H-Frame (Pallet Changer) Rotate CCW

Output # 163

H-Frame (Pallet Changer) Rotate CW

Output# 164
H-Frame at CW 0 1 0 0
H-Frame at CCW 1 0 0 0
H-Frame Rotating to CW 0 0 0 1
H-Frame Rotating to CCW 0 0 1 0

Electrical Diagrams

Pallet Changer Input Status / Solenoid Output Cable Diagrams

 

Auxiliary Front Panel Cable Diagram

EC-400 APC Gear Rack Version Change

1

The gear rack was changed to have a notch added so it would not trip the sensor before the pallet was in place. Replace the gear rack with the new version[2]. Check to see what version you have before ordering replacement part. 

Please refer to the EC-400 - APC Rotation Cylinder - Replacement procedure for further instruction on how to remove this

2

The mounting block in the image to the right was made shorter to reduce the margin for sensing when the APC is fully rotated, preventing the H-frame from lowering prematurely.  

Air Blast Manifold Seal

1

The new version of the air blast manifold incldues a groove for a shaft seal 57-0813 S SEAL 3.25 X 3.614 X .211 SL WIPER. This seal can be shown in the image denoted as [1]. 

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