Profit Pointer for Preventative Maintenance Program for Tube, Pipe and Rollform Mills

by Robert A. Sladky, Roll-Kraft Ohio, U.S.A.

Introduction

In response to popular demand, Roll-Kraft continues its popular Profit Pointers series, with this issue focusing on the subject of tube, pipe and rollform mill maintenance. The information provided in this Profit Pointer will allow mill operators to develop, or modify, their own maintenance programs to ensure efficient operation of their mills. While primarily a tooling manufacturer, Roll- Kraft believes that a properly maintained mill maximizes the performance of the tooling. Quite often, production problems and poor product quality are blamed on the tooling when, in fact, a mill problem is to blame. And in most cases, that particular mill problem could have been prevented if the mill had been properly maintained. Therefore, it is essential to develop and implement a preventive maintenance program for your mill, if such a program does not exist, to put a stop to such problems. Once in place, a preventative maintenance program will yield surprising results. Among the benefits that you will realize from a properly maintained mill, compared to a neglected mill, are quicker changeovers, reduced down time and scrap, longer tooling life and higher quality end product.

Lubrication

Lubrication is the cornerstone of any mill maintenance program. This is easy to see based simply on the number of driveshafts and bearings that require grease or oil in a typical tube, pipe or rollform mill. If these components are not properly lubricated, failure can occur. For example, more than half of all bearing failures are lubrication related. Most mills are lubricated according to a daily or weekly schedule with the frequency determined by date. It has been the experience of Roll-Kraft, however, that tube, pipe and rollform mills should be greased according to a schedule based on service time, such as hours. This is a common practice employed with construction equipment. Service time can easily be tracked with an hourmeter. If your mill is not equipped with an hourmeter, install one. Be sure that it is installed on the power side of the mill (for example, connected to the motor drive contactor). When installed in this manner, the hourmeter will only count down when the mill is running, not sitting idle. The general mill lubrication guidelines listed below are based on best practices used in the tube, pipe and rollform industry. Keep in mind that these are guidelines, not specific lubrication intervals applicable to all mills. For the specific lubrication intervals for your particular mill, contact the mill manufacturer. If the manufacturer of your mill is no longer in business, these guidelines can be used as a starting point to develop a reliable lubrication schedule. Over the course of time, the schedule can be tailored to your specific needs based on such factors as mill configuration and operating environment. Always use a high-quality, high-temperature grease when lubricating your mill. Also, a high quality oil is recommended for those applications requiring oil, such as gearboxes and oilers.

Mill Components

Mill components should be greased every 100 hours. Be sure all grease fittings are serviceable and the component or bearing is taking grease. Apply grease sparingly. More is not necessarily better. The excessive grease that flows out of a bearing or component creates a messy environment and is a waste of lubricant.

The following is a list of mill components that require lubrication (your particular mill might not be equipped with all the components listed; this list excludes AC and DC motors):

• Driven stand bearing blocks (inboard and outboard)
• Side pass rolls
• Entry guide, seam guide, turkshead
• Drive shaft universals joints (W style mills)
• Upper lead screws for top shaft adjustment
• Coolant tank support rollers
• Run out table rollers
• Looper or Floop accumulators (including pinch roll drive systems)
• Payoff reel bearings (greaseable style)
• Auxiliary equipment specific to your mill

Weld Rolls

Two-roll, ERW design welders should be lubricated every 100 hours.
Three-, four-, or five-roll HF (high-frequency) design welders should be lubricated every 12 hours.

Gearboxes

• Check the oil level every 100 hours.
• Check for oil leaks every 100 hours (repair any leaks, as needed).
• Change the oil in gearboxes every 2500 hours.

Drive Line Couplings

• Grease every 2500 hours.

Electric Motor Bearings

This group of components includes AC and DC motors, coolant pump motors, rotary transformer bearings on ERW welders, fan motors, and hydraulic motors on auxiliary equipment. These bearings should be greased every 2500 hours. Apply the grease sparingly, as overgreasing will force grease inside the motor housing, which can cause internal electrical problems.

Rotary Transformers (ERW Welders)

• Check the oil level every 100 hours.
• Change oil every 2500 hours.

MG Sets

Greaseable designs (w/ grease fittings) should be lubricated every 2500 hours. For wet bearing cup designs, check the oil level every 100 hours; change the oil every 2500 hours. Be careful not to overgrease either design, as excess grease will forced inside the motor housing, which can cause internal electrical problems.

Cut-Off Presses

Grease the lube points every 100 hours (lube points are located on the ram swing arms, crankshaft bearings, sections of the accelerator system). Cut-off presses are often equipped with oil lube systems to lubricate the die and rail systems. Most oil lube systems include visual reservoirs for checking the oil level. Check the oil level every 100 hours, or as required, based on usage (some reservoirs might require refilling before 100 hours). Inspect all oil lines to ensure that each line is (1) properly connected to its connection point and the connection is not leaking and (2) not plugged and oil is flowing through the line. Clean the oil reservoirs annually as sludge has a tendency to accumulate in the bottom of the tanks.

Hydraulic Accelerator Systems

• Check oil level every 100 hours.
• Check for oil leaks every 100 hours.
• Change oil and filters every 2500 hours.
• Driven Stand Lubrication Points (typical).
• Rollformer Lubrication Points (typical).

Air Line Oilers

Many pneumatic systems are equipped with air line oilers to lubricate the internal components of the system. Check the oil level every 100 hours, or as required, based on usage. Check the operation of the oilers to ensure that the correct amount of oil is being delivered throughout the system.

Central Lubrication Systems

Due to the fact that weld rolls require more lubrication than the rest of the mill, a central lubrication system is ideal for ensuring proper lubrication of these rolls. A central system is completely separate from the main system and its use offers many advantages. These include reduced lubrication labor, lubrication usage and cleanup, as well as increased machine life and productivity. A timer, which is wired to the run circuit of the mill, lubricates the weld rolls during production, but not when the mill is idle. Central lube systems can also be utilized in the breakdown and fin sections of the mill.

Preventative Maintenance

• Inspect the bearings for roughness and excessive end play.
• Inspect expansion arbors, linkage and hold down arms.
• Inspect turntable bearings and king pin.
• Inspect all lube points for broken or plugged grease fittings.
• Inspect brake systems.
• Inspect all powered components, hydraulic rams, expander, and hold-downs.
• Check the alignment of payoff reel with respect to the rest of the mill line.

End Welding Equipment

• Inspect the guide rolls for strip.
• Inspect the surface condition of the guide rolls.
• Inspect the guide roll bearings for roughness and excessive end play.
• Inspect the hold-down clamps for strip.
• Inspect the copper back-up plates and clamps (tig weld machines).
• Inspect the welding torch traverse system (rails, drive motor, belt, or lead screw).
• Inspect all electrical cables and connections.
• Inspect all air lines, hydraulic lines, and gas-shielding lines for leaks.
• Inspect and clean the power supply; check for proper fan operation.
• Inspect all lube points for broken or plugged grease fittings.

Many firms schedule a semiannual or annual plant shutdown to perform basic inspections, repairs, and upgrades on their equipment, regardless if breakdowns have occurred. These actions ensure that their tube, pipe and rollform mills continue to operate efficiently and safely. Performing maintenance tasks on such a regularly scheduled basis is known as Preventative Maintenance. Tube, pipe and rollform mills are production oriented machines that require ongoing maintenance to ensure reliable and productive operation. Unfortunately, maintenance is often done only when a breakdown occurs. When maintenance is only performed on an as-needed basis, the mechanical condition of the mill progressively declines, with the net result being poor product quality. Outlined below are guidelines for a preventative maintenance program for tube, pipe and rollform mills. As stated in the Lubrication section, these guidelines are based on best practices used in the industry. Keep in mind that these are guidelines, not specific maintenance tasks applicable to all mills. For the specific maintenance tasks for your particular mill, contact the mill manufacturer.

Clean Up

Plant shutdowns are especially good times to clean the entire mill. The mill should be cleaned before any maintenance work is started. A clean mill will make inspection and maintenance work much easier to perform compared to a mill that is not. Many plants use a pressure washer, connected to the coolant system, to clean the mill. Such a setup does not add any water to the system and can be used for cleaning the mill at time.

Payoff Reel

Accumulator Floop Style

It is highly recommended that an annual tune-up, performed by the manufacturer, be an integral part of a preventative maintenance for the accumulator (vertical and horizontal designs).

In addition, the following maintenance tasks should be performed every 2500 hours:

• Inspect all support and turnaround rollers (surface condition of the rollers).
• Inspect the roller bearings for roughness and excessive end play.
• Inspect all chain and gear drives.
• Inspect all linkages, air lines, and hydraulic lines for leaks.
• Inspect all pneumatic and hydraulic cylinders for leaks.
• Inspect motors and pumps and the connection couplings (if a DC motor is used, perform the DC motor maintenance tasks outlined later in this document).
• Inspect and clean the DC motor blower (if equipped).
• Inspect all sensors and proximity switches.
• Inspect all lube points for broken or plugged grease fittings.
• Inspect all guarding.
• Check alignment of the entry and exit end of the accumulator with respect to the entry end of the mill and the other auxiliary equipment.

Accumulator Looper Style

• Inspect all support and turnaround rollers (surface condition of the rollers).
• Inspect the roller bearings for roughness and excessive end play.
• Inspect all support and turnaround rollers and drums in the unit.
• Inspect the turnaround drums (crown must still be machined into the drums for proper tracking).
• Check the alignment of turnaround drums within the framework of the accumulator.
• Inspect the looper carriage cart, cables, cable winch, (motor and transmission) carriage rollers, bearings, track, and brake.
• Inspect the framework of looper assembly for cracked or broken welds.
• Inspect the pinch roll drive rollers for flatness.
• Note: If your mill is not equipped with a pinch roll drive, it is highly recommended that one be installed. Pulling the strip through the looper with the mill places a tremendous amount of additional stress on the tooling and the entire drive system. This can cause excessive wear on the tooling (40-50% greater wear rates compared to mills with pinch roll drives) and drive system components. The net result is poor product quality.
• Inspect the motor and transmission (if a DC motor is used, perform the DC motor maintenance tasks outlined later in this document).
• Inspect the dancer arm and encoders that monitor the free loop of the strip before it enters the mill.
• Inspect all lube points for broken or plugged grease fittings.
• Inspect all guarding.
• Inspect all sensors and E stop limit switches.

Entry Guide

• Inspect the guide rolls for wear (guide rolls should be replaced on a regular basis).
• Inspect the guide roll shafts for wear.
• Inspect the guide roll bearings for roughness and excessive end play.
• Inspect the shaft mounting blocks for excessive play in the gibs.
• Inspect the lead screws, side-to-side adjustment, and height adjustment (if equipped).
• Inspect surface smoothness of the horizontal lead-in roller.
• Inspect the horizontal lead-in bearings for roughness and excessive end play.
• Check the position of the entry guide; it should be mounted as close as mechanically possible to the first breakdown; move the unit, as required.
• Check the integrity of the edge trim units (if equipped).
• Check the position of the entry guide; it must be centered and at the correct height with respect to the entry end of the mill.
• Inspect all lube points for broken or plugged grease fittings.
• Inspect all guarding.

Driven Stands

• Inspect O.D. of the driven shafts; allowable undersize wear is .001” per 1.000” O.D. of the shaft.
• Inspect the bearings for roughness and excessive end play.

Note: When replacing bearings, inspect the bore of the bearing block (for the outside race) and the bearing journal O.D. (for the inside bearing race). Always preload the
bearing to the proper inch pound rotational drag. Do not preload bearings by feel.

• Inspect the outboard tower bearings for roughness and excessive end play.
• Inspect outboard tower bearing sleeves for excessive wear; allowable oversize wear is .001” per 1.000” I.D. of the original bore of the outboard sleeve.
• Check the bearing block fit to the inboard and outboard towers.

Note: If these bearing blocks do not have grease seals, it is recommended that seals be added. It should be noted, too, that if seals are installed, a grease relief must be added. The grease relief is necessary to prevent the seals from blowing out when the bearing block is greased. The grease relief should be installed on the opposite side of the end caps, opposite from the grease fitting to ensure that the grease flows through both bearings. If the grease fitting is located in the center of the bearing block, move it to the end cap.

• Verify that the top shaft is parallel to the bottom shaft.
• Inspect the integrity of the top lead screw adjustment for the top shafts.
• Inspect the jackscrews if the mills are equipped with Single Point Adjustment (SPA); if equipped with anti-back lash jackscrews, the proper preload on the bearings must be maintained.
• Inspect the driven shafts for straightness.
• Verify the shoulder alignment—top shaft-to bottom shaft and stand-to-stand.
• Inspect all lube points for broken or plugged grease fittings.

Side Pass Stands

• Inspect the side pass shafts for wear and indentations from the bearings.
• Check the fit of the side pass shafts to the shaft mounting blocks.
• Inspect the shaft mounting blocks for excessive play in the gibs.
• Inspect the lead screws and the side-to-side adjustment for looseness; eliminate any backlash.
• Inspect the integrity of the foundation components, if the height is adjustable; be sure that the foundation can hold the side pass stand plumb and upright against the formation forces of the mill during normal mill operation.
• Inspect the top tie bars (if equipped); all fasteners and lead screws must be in place.
• Check the position of the metal line in the side pass stands; the metal line must be at the proper height and centered with respect to the driven passes per the tooling design and setup chart.
• Check the position of the side rolls, if brass washers are used.

Note: Consider switching from brass washers to thrust bearings on the side rolls. Thrust Checking Bearing Play bearings allow the side rolls to rotate easier, reducing drag on the mill drive. Also, the thrust bearings eliminate the variable wear on the rolls and brass washers.

• Inspect the framework of the side pass stands for coolant; be sure that the coolant can drain properly from the areas around the shaft mounting blocks.
• Inspect all lube points for broken or plugged grease fittings.

Seam Guide (if applicable)

Seam guide units have multiple designs.

Design 1—Two horizontal rolls set up in the same manner as a side pass stand for guiding the V gap of the tube to the weld rolls.
Design 2—Two horizontal rolls set up in the same manner as a side pass stand with an insulated fin blade for guiding the V gap of the tube to the weld rolls.
Design 3—Insulated fin blade only for guiding the V gap of the tube to the weld rolls.

Inspect Design 1 in the same manner as you would a side pass stand, as the configuration is similar. Inspect Designs 2 and 3 in the same manner as you would a side pass stand, as the configuration is similar, plus perform the following tasks:

• Inspect the insulation on the two halves of the fin blade guide; the fin blades must be completely insulated from the arbors on which the blades are mounted.
• Inspect the fin blades for wear.
• Inspect the bearings on the assembly for roughness and excessive end play.
• Inspect the in-and-out adjustment for the fin blades.

Weld Boxes—ERW Type

• If your ERW configuration has two bottom weld rolls, follow the guidelines, as outlined for the side pass stands, for checking the integrity of the unit.
• If your ERW configuration has live bottom shafts, inspect the bearings for roughness and excessive end play; be sure the bearings are properly preloaded and the seals are functional; check the shoulder alignment (the weld rolls must be parallel).
• If your ERW configuration has only one bottom weld roll, inspect the shaft, bearings, and shoulder references for proper integrity.
• Inspect all lube points for broken or plugged grease fittings.

Weld Boxes—HF Type

Many designs are used for HF (high-frequency) welding. These include (1) two-roll units; (2) flat plate, three-roll design and (3) three-roll, chuck design. Four- and five-roll units are often used on larger tube and pipe mills. For two-roll units, follow same guidelines as outlined for the ERW-type weld boxes.

Inspect the flat plate (separate clevises with separate adjustments), three-roll design as follows (these guidelines should also be followed for four- and five-roll weld boxes of this design):

• Inspect the slides, gibs, and lead screws if the back plate moves up and down, and side to side.
• Inspect each weld roll clevis for proper integrity (includes the slides, gibs, lead screws, and bored holes for the weld roll shafts).
• Inspect the weld roll shafts for proper O.D. and shoulder referencing for weld roll location.
• Inspect all lube points for broken or plugged grease fittings.

Inspect the three-roll, chuck design (each weld roll is usually individually adjustable) as follows:

• Most chuck-style weld boxes are mounted on a flat, intermediate plate; most move up and down, and some side to side; inspect the slides, gibs, and lead screws.
• Inspect the chuck; these units should have grease fittings to lubricate the internal scroll; disassemble the scroll and clean it, then inspect the scroll for excessive wear and endplay.
• Inspect each lead screw in each of the three jaws of the chuck.
• Inspect each weld roll clevis for proper integrity (includes the slides, gibs, lead screws, and bored holes for the weld roll shafts).
• Inspect the weld roll shafts for proper O.D. and shoulder referencing for weld roll location.
• Inspect all lube points for broken or plugged grease fittings.

ERW Rotary Transformer

• Inspect the bearings for roughness and excessive end play; be sure the bearings are properly preloaded and lubricated.
• Inspect the insulation between the two top copper electrodes.
• Inspect the bolt hole threads for the top copper electrodes; replace any stripped-out threads or studs.
• Inspect the slip rings and brushes.
• Have a motor shop meg the rotary transformer to verify the integrity of the insulation (no current should be leaking to ground).
• Inspect all electrical connections, including the connections of the heavy cables to the slip rings.
• Inspect the motor, transmission, and chain drive that rotates the transformer, allowing the copper electrodes to be trimmed.
• Inspect the integrity of the trimming unit; a tight unit is a must for smooth trim cuts.
• Inspect the oil coolant rotary couplings.
• Inspect all hoses.
• Inspect the pump, filters, and supply tank.

MG Set

• Have a motor shop meg the generator to verify the integrity of the insulation (no current should be leaking to ground).
• Inspect the commutator and brushes, as well as all cables and connections.
• Inspect the coupling between the AC motor and the gen-set.
• Inspect the AC motor bearings for roughness and excessive end play.
• Inspect the exciter generator; inspect the coupling (if equipped).
• Service the exciter generator annually.
• Inspect all lube points for broken or plugged grease fittings.

High Frequency (HF) Welder Components

It is highly recommended that an annual tune up, performed by the manufacturer, be an integral part of a preventative maintenance program for your welder. These welders are quite complicated and are considered specialized equipment, requiring service from specially trained technicians. Special test equipment, that you might not have in-house, is also required. A tune-up will maintain your equipment in peak condition and will allow the manufacturer to upgrade it to the latest changes.

As part of your regular in-house maintenance program, perform the following tasks every 2500 hours:

• Check the distilled water level in the closed loop cooling system; check the system for external and internal leaks.
• Check the water for contamination; determine the source of contamination, correct the problem and recharge the system with clean distilled water.
• Inspect the heat exchanger for leaks.
• Inspect the temperature gauges and throttle valves for proper operation.
• Inspect the pump and motor.
• Lube the pump motor and pump (if it does not have sealed bearings) annually.
• Inspect buss bar arms; check the insulation between arms.
• Inspect the induction coil clamps and clamp fasteners.

Scarf Stands

Two basic scarf stand designs are used, (1) one-piece rotary design and (2) single- and two-knife design.

The maintenance tasks for the rotary design are the following:

• Inspect the round cutting tool saddle, as well as the hold-down clamps.
• Inspect the limit or proximity switches used for rotation change of the unit.
• Inspect the motor and gearbox; lubricate the motor and gearbox annually.
• Inspect all lube points for broken or plugged grease fittings.
• Inspect the bearings, or slip fit, of the rotary unit to the fixed base; lubricate, as required.

The maintenance tasks for the single- and two knife design are the following:

• Inspect the gibs and slides that incorporate the up-and-down feature of the stand; these areas must be tight to ensure steady, smooth cuts.
• Inspect the air cylinders (if equipped) for wear and air leaks.
• Check the cylinder air line oilers for proper operation and adjustment.
• Inspect the air cylinder-to-knife mount slide linkage; some units use cams for this purpose; if equipped with cams, check the integrity of the cams.
• Inspect scarf knife hold-down clamps and fasteners.
• Inspect all lube points for broken or plugged grease fittings.
• Inspect the support rolls, bearings, shafts, and lead screw adjustments.

O.D. Bead Winding Equipment (where applicable)

• Inspect the motor and gearbox; lube annually, if the units are greaseable.
• Inspect the fingers on the back plate.
• Inspect the bearing for roughness and excessive end play.
• Inspect the slip clutch.
• Inspect all lube points for broken or plugged grease fittings.
• Inspect the end cap/plate (where applicable) that fits over the fingers.
• Inspect any lead rolls/guides that guide the scrap on the winder.

Ironing Pass (where applicable)

Most of these units are simply an inboard and outboard stand, similar in design to a forming and sizing stand, but not driven. If your plant is equipped with this style ironing pass, follow the maintenance tasks outlined in the Driven Stand section. Some ironing passes are a three-roll design, with an eccentric on the top roll for pressure. This design is also similar to a forming or sizing stand. If your plant is equipped with this style ironing pass, follow the maintenance tasks outlined in the Driven Stand section. In addition, check the cam, or eccentric, adjustment.

Coolant Tank and Coolant System

This is the section between the forming and sizing stands where tube or pipe is cooled.

• Inspect all support rollers, bushing/bearings, shafts, and support fixtures.
• Inspect all lube points for broken or plugged grease fittings. If your unit is equipped with a top hold-down rack of rolls, inspect the rolls in the same manner as the bottom support rolls and the linkage to the top rack.
• Inspect the spray nozzles (if equipped); be sure the nozzles are not plugged, or missing.
• Inspect the valves, drains, and overflows.
• Inspect all flex coolant lines on the mill; be sure all the lines are installed, coolant is flowing through the lines, the connections are not leaking and coolant is being supplied to each driven, side pass, weld roll, and turkshead.
• Inspect the coolant pump and motor; lubricate, as required.
• Inspect the pressure and temperature gauges (if equipped).
• Inspect and service the filtration system (if equipped); depending on the design of the unit, regular daily/weekly maintenance will be required, as outlined by the manufacturer.
• Clean the coolant tank, remove all sludge, and discard the material in a proper manner.

Turkshead Units

The four basic designs of turkshead units are, (1) single four-roll cluster, (2) double four-roll cluster; (3) two-roll horizontal and (4) two-roll vertical. Some units have rotational capabilities for twist control.

• Inspect the back plates; these plates slide up and down, side to side.
• Inspect the lead screws for excessive backlash.
• Inspect the tooling clevises, including the fasteners, slides, and gibs; check for wear on the inside face; check for wear in the roll shaft bores.
• Inspect turkshead roll shafts to verify dimensions, O.D., and shoulder location.
• Check the fit between the turkshead rolls and clevises if brass washers are used.

Note: Consider switching from brass washers to thrust bearings on the turkshead rolls. Thrust bearings allow the turkshead rolls to rotate easier, reducing drag on the mill drive. Also, the thrust bearings eliminate the variable wear on the rolls and the brass washers.

• Inspect the rotary adjustment (where applicable), be sure there is no end play in the assembly.
• Inspect all lube points for broken or plugged grease fittings.

Cut-off Press

There are several designs of cut-off presses used in the industry, which include, (1) single cut, (2) double cut, (3) hot saw, (4) cold saw, (5) plasma, and (6) laser. Each design has unique maintenance requirements. The single and double guillotine cut are the most popular designs; therefore, the generic maintenance tasks for these two designs will be presented.

• Inspect the encoder wheel and its assembly; the wheel should be flat, with no grooves.
• Inspect the coupling between the encoder wheel shaft and the encoder.
• Inspect the primary lower bed rails of the die.
• Inspect the upper rails on the ram.
• Inspect the links, bearings, and crankshaft of the swinging ram.
• Inspect the swinging ram for cracks.
• Inspect the gibs on the die (upper and lower).
• Inspect the wear plates and wipers (if equipped).
• Inspect the assembly of the die (sleeves and posts, slides, die clamps, all major components).
• Inspect the spare dies.
• Inspect the brake and clutch assembly; adjust per manufacturer’s recommendations.
• Inspect the air, oil and hydraulic lines for leaks.
• Inspect the main drive motor bearings for roughness and excessive end play.
• Inspect the V-belts from the motor to the flywheel.
• If accelerator incorporates a DC motor, perform the DC motor maintenance tasks outlined later in this document.
• Inspect the accelerator drive system; check the connection shaft from the die assembly to the accelerator.
• Inspect the central oil lube system for the die and related press lube points, which include the motor, pump, reservoir, and all lubrication lines.
• Inspect all lube points for broken or plugged grease fittings.
• Inspect all guarding.

DC Drive Motors

Consider sending your DC motors to a qualified motor shop for service. The shop will clean, bake out and meg the motor, dress the commutators, replace the brushes, and re-insulate the armatures and fields, if needed. They will also check and replace the bearings. If you decide not to send your DC motors out for service, conduct the following maintenance tasks:

• Inspect the bearings for roughness and excessive end play.
• Dress the commutator, as outlined by the tool manufacturer.
• Inspect the brushes; replace, if necessary.
• Meg the armature and fields to ensure there are no leaks to ground; if either component fails the test, the motor will have to be sent to a motor shop to be baked out and re-insulated.
• Inspect blower motors (if equipped); lube the motor and clean the fan blades.
• If the motor is direct coupled to the transmission, inspect couplings.
• If the motor is belt driven, inspect the pulleys and belts.
• Inspect the motor mount and frame for cracks and looseness.
• Inspect all guarding.
• Inspect the tack feed back generators, couplings, and mounts.

AC Drive Motors

AC motors are serviced in the same manner as DC motors with the following exceptions:

• There is no commutator to dress.
• There are no brushes to replace.

Transmissions

There are two transmission designs used in the industry. The first is the M style, in which the transmission is part of the inboard stand. The other design is the universal, in which the gearboxes are mounted on an intermediate base and connected to the inboard drive stand via universal drive shafts.

The maintenance tasks for the M style transmission are the following:

• Perform the tasks outlined in the drive pass section of this document.
• Pull the covers and inspect the inside of the gearbox.
• Inspect the bearings and seals; pre-load any bearings that are replaced.
• Inspect the gearbox vents; the vents must be clear and not plugged.
• Inspect the worm shaft, worm gear, and transfer gears for wear.
• Inspect the oil transfer system to ensure oil is being delivered to the transfer idle gears for the top shaft.
• Inspect the seals and couplings between gearboxes.
• Inspect the coupling and pulley guards.

The maintenance tasks for the universal style transmission, including auxiliary two-, three- and four-speed designs, are the following:

• Inspect the bearings and seals; pre-load any bearings that are replaced.
• Inspect the worm shaft, worm gear, and transfer gears for wear.
• Inspect the gearbox vents; be sure the vents are clear and not plugged.
• Inspect the output and input shafts keyways.
• Inspect the drive shafts, U-joints, spline couplings, and welded tubing between these components.
• Check the drive shaft timing: floating joint to floating joint, fixed joint-to-fixed joint; incorrect timing will result in variable speeds of the driven stands and the tooling installed on those stands.
• Inspect all guarding.

Run out and dump tables (if equipped)

• Inspect all carry out rollers.
• Inspect the bearings for roughness and excessive end play.
• Inspect the shafts for excessive wear.
• Inspect the dump feature related components: arms, linkages, cylinders, flag switches or encoders, and back stop rails.
• Inspect the accumulation table components: collection rails, stops, conveyor belts, drives.

Summary

The importance of regular and preventative maintenance cannot be overemphasized. Remember, a properly maintained tube, pipe or rollform mill not only extends the service life of the tooling and machinery, but improves overall product quality. To assist our customers with their maintenance tasks, Roll-Kraft offers a full line of services that include mill evaluation, mill alignment, mill maintenance consulting and in-house training.

Lubrication Checklist for Tube, Pipe and Rollform Mills – 100 Hour Tasks

Lubrication Checklist for Tube, Pipe and Rollform Mills – 2,500 Hour Tasks