Providing roll tool maintenance recommendations is complicated by the fact that each tool set is designed for a specific profile.When designing a roll forming line, machine builders consider the product that will be formed – what shape it will be made into, the material of manufacture, the yield strength and elongation of the material, the total degree of bending of the part, and the tolerances applied to that part.Then they will consider whether the part is pre-cut or post-cut.These are some of the considerations for selecting tool materials.
Careful consideration of the purpose and structure of the roll forming unit will determine the most critical maintenance points on the production line.
Tools on a roll former can be made from a variety of tool steels, ranging from 4140 to D2, depending on the part it is used to produce.In addition to the substrate from which the roll is made, some tools can be heat treated, additional coatings such as ionic nitride or chrome plating can be applied, and the roll may need to be highly polished.Handling will depend on the material used for the part and what is expected of the finished product.
Understanding the materials used to manufacture rolls on a roll former will help you better understand the key components of maintenance practices.
For example, maintaining a heat-treated tool is not the same as maintaining a tool that has not been treated at all.Some low-end tools are not hardened at all.But suppliers who make hardened tools offer products that harden to between 58 and 62 Rockwell.
If you start polishing or reworking an unhardened roll, you may remove some of the processes that were added to it or change the shape of the tool by over-polishing.With a tool hardened to 62 Rockwell, you won’t do that.Pay attention to how the tool is made, so you can be sure that it doesn’t change its properties during the cleaning process.
A fundamental consideration for your roll forming line before you start running it for the first time is the environment in which it will operate.Are you in a space where there is a risk of foreign objects entering the line and interrupting the function of the rolls?If you run your rollformer in an environment where airborne particles can get into its work, these defects will transfer to the material.They will appear on your finished product.These particles can damage the finish if you run pre-painted material on the machine.Make sure you can protect the environment around the machine from this form of contamination.
Sometimes, no matter how the environment is managed, the rollers still get dirty.If you are running a Class A or pre-coated material through a roll die, any contamination may be considered a failure.In this case, it is necessary to apply something to the machine that will allow it to continuously wipe off any contamination as the rollers keep turning.This is not an easy problem to solve, but working with your roll forming system supplier it can be arranged.
The picture shows the cooling liquid roll coating system, which can directly apply the cooling liquid to the flat surface.Coolant management is a critical part of maintaining any roll forming unit.
While this may sound obvious, the machine should be locked out and labeled when doing any maintenance on the roll forming line.
Certain passes in a roll forming line work harder than others, and the tool will naturally wear out faster.If these passes are not actively managed, the wear and tear of that pass will affect every subsequent pass.Be aware of which parts of your line include these passes and check them regularly.
If you are using pre-painted material, it is recommended to avoid cleaning with any type of lubricant.If a lubricant is used, it should be a volatile oil or similar formulation that will evaporate without affecting the painted surface.The challenge with using coolant with a precoat material is that it can get trapped between the stacked bundles and damage the surface of the part.
Conversely, if you’re running galvanized steel, you must use coolant; if you don’t, the galvanized material will start sticking to the rolls.Once the galvanized material begins to stick to the rolls, it is impossible to remove through the normal cleaning process; the rolls must be removed from the machine and sent to the machine shop to be polished, recut or replaced with new rolls.
If you are running black or hot rolled steel with fouling, it is important to use coolant to extend the life of the die.Many loose carbon particles will mix with the coolant/water mixture.This requires a filter system to deal with otherwise these particles will be carried back into the tool when the coolant is reused.It is possible to run hot rolled or black steel without coolant, but the life of the tool will be greatly reduced.
It is important not to let the rolls touch each other.If the material is pushed into the roll too hard, sometimes the rolls on the top and bottom of the part can be knocked out of parallel and end up rubbing against each other when no part is going through the machine.Rolls rubbing against each other can cause damage.During maintenance, be sure to check for roll retention or realignment.
Sometimes the rollers do not match the surface speed of the material.If left unchecked, volumes can be graded by material.To avoid this problem, it is necessary to add lubricity to the tool or apply more coolant to the roll.The coolant serves two purposes: it provides lubricity, and it cools the material as the process generates heat.Without coolant, the part can get so hot that its shape may change after the molding process is complete.
In this image and the first image of the article, we see a coolant injection system.The benefit of using a spray system over a roll coater is that it can deliver coolant in any shape, size or form.
Tools used for vertical passages where speeds cannot be matched are called free-running rolls.The purpose of these volumes is to contain parts on their path.They run fine, but have bearings and bronze bushings in them that require regular lubrication.These bearings should be checked for lubricity and ensure that there are no foreign objects locking the bearings.
In some cases, side rollers are required to hold the material in place to match the speed of the process.Instead of running horizontally, they run vertically or at different angles to match the speed.Usually the side rollers have different supports and different bearings and must always be lubricated.
It is now possible to equip your roll forming line with sensors to warn of possible future failures.These sensors monitor the heat level registered in the bearing.If the sensor notices that the temperature recorded by the bearing exceeds a certain threshold, there is a problem.Either the bearing is wearing out because it wasn’t lubricated properly, it’s drying out, or the tool is generating a lot of force that it didn’t have before.
The point of sensors is that they allow you to pinpoint where the problem might be.Some shops use a heat gun as a makeshift solution to the same problem, but it is far less accurate than these sensor technologies.Like many other Industry 4.0 innovations, sensors are an important aspect of next-level preventive maintenance practices.
Coolant mixing is very important.If you use coolant mixed with water, be sure to follow the recommended dilution levels.If too much cooling oil is used, this will cause problems for the part, either damaging any paint or finish, or making it too slippery to pass properly through the roll forming line.Excessive water may damage the machine.It gets into the machine joint and stays there, and it may not be possible to remove the tool from the shaft due to water damage.
Additives are sometimes added to coolants to keep them from breeding bacteria.Make sure that any additives used do not affect any other parts of the machine, such as seals or finishes used on parts formed on the production line.
The condition of incoming steel can also shorten tool life.For example, severe burrs on the edges of the material can damage the rolls prematurely.Burrs can be removed by proper cutting before the material enters the machine or by a deburring process set up at the beginning of the production line.
This article begins by discussing the uniqueness of each coil machine design.However, when you build your production line, there are some important roll die manufacturing standards to keep in mind.By following these standards, you can help your tools last longer.
For example, a 4-inch diameter tool can be used to make a specific shape.However, a roll forming tool manufacturing standard for that shape would probably recommend a 6″ diameter tool because each revolution will give you 18″ of that shape instead of 12″ and the tool’s lifespan will be that of the shape 1.5x 4″ diameter tool.Details like this and keeping the coolant at the proper dilution level will save time and money in the long run.
Post time: Apr-01-2022