Posts Tagged ‘Installation’

Press Clutch/Brake Hub Mounting Options

Tuesday, November 13th, 2012
There are many methods to mount a Clutch/Brake hub to the shaft of a Stamping Press or other heavy machinery. Torque Inc will help you pick the best type of connection for your application.  The following is a summary of the benefits and limitations of the various methods:

Key with clearance

Using a clearance fit between the hub and the shaft while and hand fitting the key (or two keys) is the most common method. Clearance of a couple of thousandths of an inch with line/line for the keyway is typical. This connection will likely gradually get loose at some point in time, is likely the most common type used on a press.

Key with interference

Adding a slight interference with a hand fit key is a more permanent solution, albeit requiring a modest heating of the hub (to about 250- 300 degrees F through via oil bath, oven or induction heater). Typical fit of line/line to .001”/.002” for shaft size of 6”.

Key with heavier interference

Increasing shrink to .0005” per inch of diameter (ie. .003” interference for 6” bore ) is achievable with a 300-400 degree heat and dry ice of the shaft. This fit is recommended for high shock load/high reversing loads like shears and high stripping force dies, cold forging etc. Care must be taken not to end up with too tight a fit over a key, in that this can cause the hub to split through the keyway. Heavy interference fits are difficult to remove without damaging the shaft/bore interface.

Heavy Interference without key

Using  a .001” per inch of shaft diameter interference (ie. .006”-.009” shrink for a 6” shaft) , or more, can often times gain enough torque to drive without a key or supplemental locking device. However, we do not recommend retrofitting using this method due to the following problems, indluding but not limited to:
1. Precise material specifications are required,
2. Precise machining is required,
3. Installation is tricky
4. Removal does damage to the shaft and hub bore.

The best system is a Engineered Locking Element without a key

Using an engineered locking device such as a Ringfeder, Climax or Bloc creates the advantages of heavy inference shrink fit connection (ie. No backlash ever, removability, ease of assembly and strongest possible shaft and hub design due to no stress risers from keys) without the disadvantages. Some applications are hard to retrofit due to space and material issues. These devices require proper dimensions and installation procedures and torque instruction be followed in order to function properly. However the devices have a 100% success rate when properly engineered and installed (in fact they frequently can carry more torque than the shaft itself can!) .
There are two primary types of keyless locking devices.
Shrink Disc Wichita CCB hub mounting

Wichita Clutch CCB with Shrink Disc mounted hub

The “shrink disc” goes outside of a hub extension and squeezes the hub to the shaft. Advantages are a infinite choice of shaft sizes (ie. Can match any existing shaft assuming it is round and finished properly) and has a relatively high torque rating. Material can be cast iron or steel
Industrial Clutch Hub mounted with Internal Locking Device

Industrial Clutch Hub mounted to shaft with internal locking element.

The internal “locking assembly “ is sometimes easier to fit in (goes inside existing hub) but can only fit a finite number of standard shaft sizes and requires an adequate OD to provide enough strength the keep hub from cracking. Material required to be steel or steel sleeved cast iron.
  • Proper selection of either version of an engineered locking element requires the qualified engineering assistance that Torque Inc. can provide to insure a successful installation.
  • Often the cost of the device is offset by the reduction in labor/machining cost associated with putting a connection together!

Quick Release Valves (QRV’s)

Tuesday, June 14th, 2011

Most industrial Air Clutch/Brake applications have Quick Release Valves (QRV or Quick Exhaust) engineered into the air system to provide rapid exhaust of the air pressure by providing a large exhaust port right at the clutch or brake.  Air systems with properly engineered, installed and maintained QRV’s,  offer significantly improved operation of clutches and brakes in high cycle applications (single stroke operation of a press).

To properly engineer, install or maintain a system with QRV’s,  it’s important to understand what they are and how they work.  The most popular QRV’s supplied by Torque Incorporated are:

Quick Exhaust

Wichita QRV - Quick Release Valve (Quick Exhaust)

Industrial QRV

Industrial Clutch QRV - Rotary Seal

The Wichita QRV’s are engineered to mount to the Airtube Spuds to provide rapid exhaust from the Wichita Clutch/Brake.  The Industrial Clutch QRV – Rotary Seal is engineered to mount to the Cylinder of an Industrial LK Clutch (and Verson clutches) to provide rapid exhaust and controlled clutch engagement by modifying the orifices in the poppet assembly.

Quick Release Valve (QRV or Quick Exhaust) operation is fairly easy to understand, the basic schematic using a Quick Release Valve (QRV or Quick Exhaust) is below:

QRV Basic Schematic in Clutch/Brake Air System

QRV Basic Schematic in Clutch/Brake Air System

When the 3/2 valve is engaged to pressurize the clutch/brake, the air pressure at P1 is greater than the air pressure at P2 causing the poppet in the QRV to close the exhaust port, allowing air to flow from the supply to the clutch/brake.  When the 3/2 valve is released, removing pressure from the Clutch/Brake, the air pressure P1 is less than the air pressure P2 causing the poppet in the QRV to seal off the input.  This allows the the air to exhaust the clutch/brake directly through the QRV.

While the operation of QRV’s is very simple,  we see many issues with their application and installation.

  • When QRV’s are installed it is critical that the volume of air between the 3/2 valve and QRV is small enough so P1 remains significantly lower than P2 until the clutch/brake is fully exhausted.
  • QRV’s should never be installed in series.
  • QRV’s are typically only used on Clutches in Stamping Press applications when a separate clutch and brake are used.

QRV’s have wearing parts, their operation should be checked regularly as part of your Preventative Maintenance Program or if you experience erratic stopping or an increase in stop time.  Checking operation can be accomplished by simply cycling the air system and monitoring the QRV to ensure there is a strong puff of air when the system should exhaust.  If the QRV does not respond with a strong blast of exhaust, it should be replaced or rebuilt depending on style.

It is best to run QRV’s without mufflers, if possible, the mufflers tend to slow the exhaust and trap air system contaminates in the QRV.  If you need to abate the noise created by the QRV, use a muffler with a large surface area to not restrict the exhaust flow.

Your Torque Inc. local Sales Engineer is an expert with QRV’s and is available to help you with any issues with your clutch/brake air system design, installation, operation and maintenance.  If you have any questions give us a call, we are happy to be of service.

Protect Your Teeth!!!

Monday, October 11th, 2010

Brake Drive Plate with teeth worn by excessive angular alignment.

Above is a photo of a customer who was rapidly wearing teeth of a Wichita 118 KKB.  This is a typical symptom of excessive angular alignment.

Uncoiler Brake with rapid tooth wear, ready to check alignment.

Angular Alignment was over .300", Wichita specification is .009" TIR.

Angular Alignment is checked by placing the magnetic base of a dial indicator of the shaft and indicating the face of the back water jacket at an 18″ diameter (for Wichita 118″ KKB).  This application indicated over .300″ TIR, well beyond the maximum limit of .009″ TIR published by Wichita Clutch.  This explains the rapid tooth wear of the Drive Plates and Hub.  It was noted the high/low point wear at 3 o clock and 9 o clock with the 12 and 6 o clock positions being the same reading.

Steel Uncoiler using Pillow Block Bearings that need to be restrained.

Uncoiler is built using Pillow Brock Bearings to support the mandrel.  This design, like others we see using Pillow Block Bearings, has the tension force in the same plane as the Pillow Block Bearing mounting surface.  Under high tension operation there is a real potential for the bearings to slip.  Most users correct this design issue by welding hard stops to the uncoiler base with jacking screws to restrain the bearings from sliding and allowing easy adjustment for brake alignment.

Don’t Starve your Clutch

Monday, July 19th, 2010

Many times when Torque Inc.  gets called to help customers with Clutch and Brake problems we find the root cause is an inadequate air system starving the clutch and/or brake.  Below is an excellent example of this phenomenon with a separate Clutch/Brake application on a high speed shear.

Starving the Clutch and Brake

Air system starving Clutch and Brake

The clutch is the Blue Pressure Line and the Brake is the Red Pressure Line.  You will notice it takes over 200 msec to get the brake to 60 PSI and the same time for the clutch to reach 50 PSI.  A larger surge tank will greatly reduce this time and allow much more consistent operation and better tonnage higher in the stroke in press or shear applications.  You will also notice there is no overlap during engagement because of a timer in the controls delaying the clutch valve firing.  There is considerable overlap during disengagement, which was corrected by adding another timer below:

Air sytem starving Wichit Clutch and Brake on Shear

Air sytem starving Wichit Clutch and Brake on Shear, no overlap.

Notice how the Blue pressure curve of the clutch now drops off quickly before the brake sets.  In addition to being done with a timer in the control system, Torque Inc. application engineers can accomplish this same function with a properly designed Herion Press Safety Valve system using two XSz valves and adjusting the timing in the pilot circuit.

Wichita Clutch ATD 236 LIC test on Quill Shaft Gear Box

Saturday, July 17th, 2010

Testing of rebuilt pendulum shear gear box by Horsburgh & Scott Rebuild Center.  Video shows Wichita Clutch ATD 236 LIC mounted to Flywheel on intermediate gear Quill Shaft.  Wichita ATD 260 LIB mounted on output shaft on back of gear box.

httpv://www.youtube.com/watch?v=F7B3NNB7hgw

Torque Tips – Air System

Wednesday, April 21st, 2010


TORQUE TIPS – AIR SYSTEM

AIR SYSTEM TROUBLE SHOOTING

Most Air Clutch/Brake operating problems are caused by the air system. Torque Inc. finds the majority of issues with our customers air Clutches/Brakes are air system related. Application problems:

* Inconsistent starting/stopping

* Brake heating

* Clutch slipping

* Rapid wearing of friction material

Reliable air Clutch/Brake operation requires a properly designed and maintained air system:

* Sufficient air volume supply

* Correct operating pressure

* Properly sized air lines

* Valve selection

* Reliable control response/timing

Call a Torque Inc. application engineer to assist your inspect your air system. Torque Inc. has the experience and expertise to ensure optimum operation of your Clutches and Brakes. In addition to general air system consultation, Torque Inc. offers a charged “Overlap Service” to monitor your air system in real-time with our high speed data acquisition system. The data acquired through our “Overlap Service” can optimize control settings and identify operational issues with your air system.

Torque Inc. recommended air system designs are available on the links below:

ABOUT TORQUE INC:

Torque Inc. has represented Wichita Clutch for 60 years and continues to provide Heavy Duty Clutches/Brakes to the Metal Forming, Coil Processing, Converting, Printing, Marine, Mining and other heavy industries. Our staff of expert application engineers and professional customer service representatives is available to support you with:

  • Technical Support
  • New Application Engineering
  • Retrofit Engineering
  • Genuine Parts from our Extensive Inventory
  • Clutch/Brake Rebuild Service
  • New Units from our Extensive Inventory

Torque Tips – Wichita/Industrial Clutch and Brake Alignment

Wednesday, April 21st, 2010

TORQUE TIPS – ALIGNMENT

ALIGNMENT TROUBLE SHOOTING

Reliable air Clutch/Brake operation requires proper alignment. Proper installation needs to ensure both Parallel (concentricity) and Angular Alignment of the Clutch/Brake Ring (Housing) to the shaft.

* Brakes are more sensitive to Angular Misalignment

* Clutches are more sensitive to Parallel Misalignment

Call a Torque Inc. application engineer to assist your inspect your Clutch/Brake Alignment. Torque Inc. has the experience and expertise to ensure optimum operation of your Clutches and Brakes.

Checking the alignment of a Clutch/Brake requires the use of a Dial Indicator and Magnetic Base. In addition, the ability to rotate the shaft while Ring/Housing is held in place is required.

* Mount base to hub or shaft, Indicator Tip machined face (OD of friction area on Back Plate or face of Ring). While rotating shaft note the TIR (Total Indicator Reading) for full 360 degree sweep.

* Mount base to hub or shaft, Indicator Tip machined face (ID of Ring). While rotating shaft note the TIR (Total Indicator Reading) for full 360 degree sweep.

Below is a link to the Wichita Alignment Instructions, for details:

Low Inertia Clutch/Brake Alingment Procedure

ABOUT TORQUE INC:

Torque Inc. has represented Wichita Clutch for 60 years and continues to provide Heavy Duty Clutches/Brakes to the Metal Forming, Coil Processing, Converting, Printing, Marine, Mining and other heavy industries. Our staff of expert application engineers and professional customer service representatives is available to support you with:

  • Technical Support
  • New Application Engineering
  • Retrofit Engineering
  • Genuine Parts from our Extensive Inventory
  • Clutch/Brake Rebuild Service
  • New Units from our Extensive Inventory