Reverse Tonnage - Part 3: Give Your Press a Lift

Your press in many ways is absolutely vital to the success of your business.  The thump, thump, thump of your press is the heart beat of your company.  With every thump another part is made and your business prospers.  To keep that heart beat strong your operators need to be sure to make the proper setups and adjustments on your press as required for each job.  The Air Counter Balance is one of the easiest adjustments to make on your press.  Yet this very important system adjustment is many times over looked to the long term detriment of your press.  If overlooked for too long the cumulative damage caused by not properly adjusting the Air Counter Balance for each job can be so severe it can  require a complete rebuild of the drive train of your press.  This is a very costly repair that is easily avoided.

A typical Air Counter Balance System will incorporate an Air Cylinder(s), Air Regulator, Pressure Gauge, Air Dryer with Filter, System Decompression Valve, and a Compressed Air Tank (Reservoir) with Drain Plug and an Over Pressurization Relief Valve.  Depending on the size of your press the Air Counter Balance System will incorporate one or two Air Cylinders.  If there are two cylinders, one cylinder is located on each side of the press left and right.  Compressed air to power the system is provided by an outside source.  

‍When in operation starting at Bottom Dead Center of the rotation cycle air from the air reservoir is pumped into the bottom of the air cylinder.  The ram (picture right) of the air cylinder is connected to the upper slide of the press which also holds the upper die tooling.  When in operation and adjusted properly a metered amount of compressed air fills the air cylinder at a specific pressure and rate. This in turn drives the cylinder ram upward at the same speed as the rotation cycle of the press.  The Air Counter Balance System will lift the combined weight of the upper slide and the upper die tooling for the drive train of the press.  Once the press has reached Top Dead Center the compressed air is released from the air cylinder(s) at a metered rate that will match rotation speed of the press.  This will keep back pressure against the upper slide and drive train.  This keeps all the connections in the drive train in a (compressed) state.

Why does a Press need an Air Counter Balance System?

The rotation cycle of a press can be separated into two distinct halves: the Downward Stroke (Past TDC approaching Bottom Dead Center - Compression) and an Upward Stroke (Past BDC returning to Top Dead Center - Tension).  All the connections in the drive train of your press are designed with small clearances in them to allow the metal surfaces to slide passed each other.  During the Downward Stroke of the rotation cycle the connections of the drive train press against one another in the same direction to move the tooling forward to complete its work.  This drives all the small clearances to one side of all the connections throughout the entire drive train.  Think of the drive train as being under compression pushing forward to deliver the working energy to the tooling. However, once the press has reached BDC and the Upward Stroke begins the workload now goes in reverse (Tension).     

During the Upward Stroke the drive train must lift or pull the Upper Slide along with the Upper Die Tooling to TDC.  The amount of weight to be lifted can be significant.  Now the drive train is under Tension.  All the forces in the drive train are reversed.  Instead of pushing forward (compression) to deliver working energy to the tooling the drive train is now pulling (tension) to lift the upper slide and upper tooling.  Without an Air Counter Balance this reversal in workload will cause all the small clearances in the connections of the drive train to instantaneously move to the other side of the connection.  

Over time without the Air Counter Balance being properly set will have the same devastating effect on the drive train as Reverse Tonnage.  By allowing the constant uncontrolled reversing of the work load on the connections in the drive train with every stroke of the press will damage the connection points and will over time require a major rebuild of the drive train.  In short the Air Counter Balance will prevent the reversal of the workload keeping the drive train under compression there by preventing the engineered clearances in the drive train from moving back and forth.  

We now know what an Air Counter Balance System is, what the system does and why it is important to properly adjust this vital system for every job processed.  In the next issue of Press On and Forge Ahead we will examine how to properly set the Air Counter Balance and proper maintenance of this system.

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Reverse Tonnage - Part 3: Give Your Press a Lift

Your press in many ways is absolutely vital to the success of your business.  The thump, thump, thump of your press is the heart beat of your company.  With every thump another part is made and your business prospers.  To keep that heart beat strong your operators need to be sure to make the proper setups and adjustments on your press as required for each job.  The Air Counter Balance is one of the easiest adjustments to make on your press.  Yet this very important system adjustment is many times over looked to the long term detriment of your press.  If overlooked for too long the cumulative damage caused by not properly adjusting the Air Counter Balance for each job can be so severe it can  require a complete rebuild of the drive train of your press.  This is a very costly repair that is easily avoided.

A typical Air Counter Balance System will incorporate an Air Cylinder(s), Air Regulator, Pressure Gauge, Air Dryer with Filter, System Decompression Valve, and a Compressed Air Tank (Reservoir) with Drain Plug and an Over Pressurization Relief Valve.  Depending on the size of your press the Air Counter Balance System will incorporate one or two Air Cylinders.  If there are two cylinders, one cylinder is located on each side of the press left and right.  Compressed air to power the system is provided by an outside source.  

‍When in operation starting at Bottom Dead Center of the rotation cycle air from the air reservoir is pumped into the bottom of the air cylinder.  The ram (picture right) of the air cylinder is connected to the upper slide of the press which also holds the upper die tooling.  When in operation and adjusted properly a metered amount of compressed air fills the air cylinder at a specific pressure and rate. This in turn drives the cylinder ram upward at the same speed as the rotation cycle of the press.  The Air Counter Balance System will lift the combined weight of the upper slide and the upper die tooling for the drive train of the press.  Once the press has reached Top Dead Center the compressed air is released from the air cylinder(s) at a metered rate that will match rotation speed of the press.  This will keep back pressure against the upper slide and drive train.  This keeps all the connections in the drive train in a (compressed) state.

Why does a Press need an Air Counter Balance System?

The rotation cycle of a press can be separated into two distinct halves: the Downward Stroke (Past TDC approaching Bottom Dead Center - Compression) and an Upward Stroke (Past BDC returning to Top Dead Center - Tension).  All the connections in the drive train of your press are designed with small clearances in them to allow the metal surfaces to slide passed each other.  During the Downward Stroke of the rotation cycle the connections of the drive train press against one another in the same direction to move the tooling forward to complete its work.  This drives all the small clearances to one side of all the connections throughout the entire drive train.  Think of the drive train as being under compression pushing forward to deliver the working energy to the tooling. However, once the press has reached BDC and the Upward Stroke begins the workload now goes in reverse (Tension).     

During the Upward Stroke the drive train must lift or pull the Upper Slide along with the Upper Die Tooling to TDC.  The amount of weight to be lifted can be significant.  Now the drive train is under Tension.  All the forces in the drive train are reversed.  Instead of pushing forward (compression) to deliver working energy to the tooling the drive train is now pulling (tension) to lift the upper slide and upper tooling.  Without an Air Counter Balance this reversal in workload will cause all the small clearances in the connections of the drive train to instantaneously move to the other side of the connection.  

Over time without the Air Counter Balance being properly set will have the same devastating effect on the drive train as Reverse Tonnage.  By allowing the constant uncontrolled reversing of the work load on the connections in the drive train with every stroke of the press will damage the connection points and will over time require a major rebuild of the drive train.  In short the Air Counter Balance will prevent the reversal of the workload keeping the drive train under compression there by preventing the engineered clearances in the drive train from moving back and forth.  

We now know what an Air Counter Balance System is, what the system does and why it is important to properly adjust this vital system for every job processed.  In the next issue of Press On and Forge Ahead we will examine how to properly set the Air Counter Balance and proper maintenance of this system.

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