This article will take an in-depth look at roller conveyors.
The article will bring more detail on topics such as:
This chapter will discuss what roller conveyors are, their construction, and how they function.
Roller conveyors are a type of conveyor belt that allows objects to skate on its surface by using rollers, which are equally spaced revolving cylinders. They transport stuff from one location to another, frequently utilizing gravity or small engines.
The transported material must have a sturdy riding surface supported by at least three rollers. They are good for accumulation applications, and rollers can reduce product inertia at greater speeds, making them useful conveyors following high-speed sorting machinery. Because of the simplicity of the construction of these conveyors, various advances have been developed to allow roller conveyors to stay relevant within industry developments. The drive roller conveyor is the most noteworthy upgrade, with each roller attached to a motor through a /chain/shaft/belt to exploit controllability. This equalizes the velocity at which materials go down the pathway and allows these conveyors to be used in reverse, from low to high elevations. They can be used in bi-directional applications since the rollers can direct material in both directions by simply altering the motor direction.
A conveyor system is a technique of transporting products, packages, supplies, equipment, and parts for use in manufacturing, relocation, or transportation. Conveying systems come in a variety of configurations, including pneumatic, belt, screw, and roller. Individual systems are built depending on the resources to be moved, including their size, weight, and transportability. Conveying systems are vital for material handling and production, but they are also utilized in other manufacturing applications such as sintering, part washing, and part and assembly finishing. They are usually automated, but unautomated variants with chutes and rollers are used in material handling, retail, and shipping applications.
There are several types of roller conveyors, each with its own specific design besides the generic parts that all of them have. Powered roller conveyors employ small belts and plastic spools to produce traction to the rollers, but they also allow products to pile on the conveyor if a line exists. Friction belts or chains typically operate heavy duty roller conveyors beneath the conveyor frame that are connected to a shaft that spans the length of the conveyor's frame. The shaft is linked to an electric motor, which drives the rollers' spinning. However, there are generic parts to all roller conveyors, and they will be discussed below.
These are metal cylinders fitted into the structure together with two bearings and a metal axis. This component differs in other types of conveyors, replaced by chains or belts. Rollers, chains, and belts are often joined within one circuit.
Plastic rollers are a less expensive alternative to metal rollers. Plastic rollers are a low-cost option that does not sacrifice quality. They're ideal for a variety of industries because they make cleaning quick and easy. Stainless-steel rollers are a more expensive alternative to plastic rollers, but that doesn't mean plastic rollers aren't the right choice for a workplace.
Plastic rollers are simple to clean and, when combined with stainless steel rollers, are the best option for transporting parcels in the food industry. Plastic rollers are the best option for hygienic rollers that are ideal for moving portable products in a business.
Rubber-coated gravity rollers can be used for a variety of applications. To begin with, where the product is delicate and prone to damage, the rubber coating allows for gentler handling. In addition, where the product is likely to be easily marked, a non-marking rubber coating can be used to prevent this.
Rubber-coated drive rollers allow for increased friction between the roller and the driving belt. This is especially useful when there is belt slippage.
Steel and stainless steel rollers are two of the most popular materials. They're simple to clean, long lasting and strong and capable of moving heavy duty materials. As a result, they are a dependable investment for a variety of industries.
The adaptability of steel and stainless steel rollers is another advantage. Stainless steel rollers are compatible fit with any conveyor belt, no matter how simple or complex the system is. They can also be modified to accommodate smaller diameters, precision bearings, or fixed shafts. This means that the stainless steel rollers can be adjusted to meet the needs of the workplace.
They support the rollers. They are made of steel because of its strength and durability in supporting heavy loads. The steel type is dependent on the weight the structure will bear. The structure and legs determine the conveyor’s movement direction.
For constant speed or fixed speed roller conveyor systems there are a wide variety of AC motors. AC induction motors are perfect for roller conveyor systems which operate continuously in a single direction. For conveyor systems for vertical applications or where the load should be held in place, there are a wide variety of AC motors with switch-off activated electromagnetic brakes.
Where the motor must run continuously in a single direction at synchronous speed irrespective of the load's torque, synchronous motors are available. The low-speed synchronous motor is perfect for frequent stopping, starting, and reversing.
For roller conveyor systems where speed must be controlled or varies during operation, AC speed control motors, gear motors, and brushless DC motors (BLDC motors) give constant torque irrespective of load size and wide speed control range.
For conveyors that need higher accuracy positioning, stepper motors and servo motors are suitable. Stepper motors, have an ability to produce high torque at low speed yet reducing vibration, are perfect for applications needing fast positioning over a short length. Servo motors are simple to use and necessitate smooth function with large belt mechanisms and inertia loads. Servo motors are perfect for positioning over a long distance by means of a flat torque method from low to high speeds.
Speed changes may be performed by joining a control circuit with the motor. Speed control motors are best for switching between low and high speed operations and for arbitrary speed adjustment.
The non precision bearings include:
The inner and outer ring raceways of angular contact ball bearings are designed and developed to be positioned close to each other in the bearing axis' direction. This enables them to cater to combined loads while also acting radial and axial loads at the same time.
Angular contact ball bearings support conveyor belt rolling shafts. This is a long cylindrical structure that makes up the main section of the conveyor and can roll and handle the weight of the workload.
Pillow block bearing, also known as plummer block bearing, is a pedestal that can support a spinning shaft with the aid of various accessories and compatible bearings. The assembly is made up of a mounting block that houses a bearing. The housing's insert bearing can be bolted onto a support surface.
These bearing types are frequently used in the most demanding beverage and food environments. To ensure a tight fit, the inside of the bearing is usually 0.025 mm bigger than the shaft. The majority of pillow block bearing housings are made of cast steel or cast iron.
Conveyor sprockets (engineering class sprockets, engineered sprockets, mill sprockets) are used together with conveyor rollers or conveyor chains. They have profiled wheels or toothed gears that mesh with a conveyor roller or chain to transmit rotary motion.
The purpose of a roller conveyor is to move items from point A to point B with relatively little effort, quickly and reliably. The speed, direction, curvature, and size of the roller conveyor vary depending on the user’s requirements. A roller conveyor is used in some industries to transport items through a manufacturing or wrapping line and back out again. It may also stack items at the end of a transportation line. Another function is to move items horizontally or vertically with precise flexibility.
A conveying system can be integrated into an operation in a variety of ways to improve efficiency and speed. There are several critical factors to consider before installing a conveying system. Each system is tailored to the requirements of a certain application.
Conveying system manufacturers consider the available space while designing a system. This step necessitates the identification of interaction sites, clearances, impediments, or any other areas that may impede material movement. Though automated systems are the most popular, whether the system is motorized or manual is determined by how it is used.
The frame is often made of aluminum or steel, depending on the amount of loading on the system and the value of the rated frame's capacity. Rollers are substantially more variable in composition because they come into direct contact with products and can influence their movement. Some rollers are covered in plastic or rubber to increase friction, while others are just aluminum or steel drums; a roller that will keep products on the line while not compromising its integrity must be picked.
The size of the material on the conveyor, as well as the ideal layout of the conveyor, must be determined so that it does not impede the movement of the products. The first step is to determine the size of individual rollers, which is done by taking into account the load and the loading conditions. A heavier, high impact load, for example, necessitates larger rollers, whereas a slow, low impact load necessitates smaller rollers.
The spacing of each roller is then determined by estimating the length of the load touching the conveyor surface and calculating the spacing so that three rollers are at all times in contact with this surface. Finally, determining whether or not the products will hang from the conveyor; if it is then, a high set roller conveyor with overhang must be purchased. A low set roller conveyor must be considered if the product must be contained inside the conveyor dimensions.
Once the system has been set out and given a pattern, the quantity of material it can carry must be established. Overloading a system could lead it to malfunction or stop working in the middle of its execution. The overall length, bed breadth, and drive system all have an impact on load capacity. Gravity roller conveyors are ideal for flat-bottomed, light-to-medium-weight goods like totes, boxes, and bags, but they should not be used for extremely delicate and cumbersome geometries like electronics and manufacturing parts.
A conveying system's speed is measured in feet per minute (fpm). The average speed of most conveying systems is 65 feet per minute, which is how fast a person walks when carrying a 50-pound load. Though this is the average, the speed can be adjusted to suit the application.
Roller conveying systems are available in a wide range of shapes, styles, sizes, and configurations. They might be straight, angled, horizontal, or curved, and they can have pockets or slats as well as z-frames. It would be impossible to discuss all of the numerous configurations because each system is built to fit a certain application. Flat belt roller conveyors, for example, cannot be used if there is curvature. Similarly, if hundreds of feet must be crossed, a more efficient design, such as a line shaft roller conveyor, must be considered so that energy is conserved wherever possible. What is critical to understand is that, regardless of the application, there are very few limits on implementing a conveying system.
The power that moves materials in an automated conveying system is referred to as the drive. It features a counter bearing to keep goods moving and facilitates movement down the belt. They can be constructed to transport goods in both ways and can be positioned in the system's middle, beginning, or end. Overhead systems, while having comparable drives, might be sprocket or chain operated.
Depending on their design, drive systems can have a single or variable speed. They usually have a gear system that is powered by a motor. Variable speed drives have become common for modern conveying because they allow for material flow variations.
Finally, the desired mobility of the product, how much control should be permitted, and the environment in which the conveyor will work must be examined. If there will be a lot of heat, dust, filth, and wetness, a more durable design, like a chain roller conveyor, is required. If precise timing and zero pressure are required, high-tech roller conveyor choices that will deliver the required precision must be considered. There is no need to look any further than the basic gravity or belt roller conveyor if a rapid, low-tech means to transfer an object from point A to point B is required.
The Occupational Safety and Health Administration (OSHA) regulates conveyor systems, which must meet federal safety standards. The regulations are known and followed by all conveyor manufacturers. Conveying systems are a preventative strategy that keeps personnel from having to lift and transport heavy objects.
The different types of roller conveyors include:
The gravity roller conveyor is the most basic of these types, consisting of a frame containing free-rotating rollers and utilizes gravity to move material down the line. They are used to transport light to medium-weight objects that do not need a motor, making them cost-effective choices for designers.
They are frequently made of steel, aluminum, and plastic and can be purchased with attachments such as curves, slide rails, supports and hanging brackets, pop up stops, and more. They are frequently used as temporary conveyors, replacements for skate wheel conveyors, in heavy-duty applications, and for stacking loads that do not need any special scheduling.
The belt-driven live roller conveyor powers each roller with a motorized belt, allowing this conveyor to control the movement of the materials being delivered. When goods must be halted briefly at control points, products must be turned, and/or side unloading or slide loading is required, they are recommended over standard belt conveyors.
For curved roller conveyors, the belt can be V-shaped or straight. Because the rollers on some belt-driven roller conveyors are higher than the frame, they can support goods wider than the frame width. In any configuration, the rubber belt beneath the rollers should not come into contact with moisture, extreme heat, or debris, as these conditions will quickly destroy the system. These conveyors are frequently used to transport medium to heavy items that are clean and dry and require occasional pausing and/or reversible operation.
The chain-driven roller conveyor is similar to the belt-driven conveyor, except instead of belts, a chain is used to power each roller. They are utilized when heavy-duty transporting is necessary when normal belt-driven conveyors cannot be employed due to harsh conditions. A roll-to-roll chain conveyor has the chain wraps around each roller and is attached to two sprockets on each roller. Because the power transfer is high in these systems, they are ideally suited for extreme duty loads and reversal operations.
These differ from single strand chain powered roller conveyors, in which a non-looped, single continuous chain drives the rollers through sprockets on the roller. The chain is kept engaged at all times by a continuous hold down area, but this conveyor is only rated for medium to heavy-duty use since it is not as powerful as its roll-to-roll equivalent.
Line shaft roller conveyors are driven, as the name suggests, by a rotating shaft to which each roller is belted. They are connected to the line shaft individually by drive spools and urethane belts, making this type of conveyor silent and simple to maintain. While the conveyor is still powered, the drive spools will fit in the presence of minimal back pressure (force on the rollers when the product has gathered and cannot move down the line), leading the rollers to simply halt without affecting others.
A line shaft can power over 100 feet of straight and curved rollers, boosting the conveyor system's efficiency. They are reversible and are appropriate for accumulation, sorting, low back pressure, and more medium-to-light-duty applications.
Zero pressure roller conveyors (also recognized as pressureless accumulating conveyors) are designed to keep any items on the conveyor from touching. They are a high-tech control system that uses sensors and motors to activate and deactivate specific 'zero pressure' zones of the track. By doing so, a buffer zone is formed between products, preventing accumulation. Certain rollers are powered internally by motors that are directly connected to the controlling system, and photocells identify when an item enters or exits zones.
These conveyors are available as kits to repurpose older conveyor systems and are preferred for automation applications requiring timing, rate of movement, and consistency. While more complex and electronically actuated than past roller conveyors, zero pressure design conveyors are quite efficient and regulate material flow, resulting in a smoother overall transfer.
This is an advanced type of roller that is powered, thus the name power roller conveyor. Power inclusion is chosen because it helps propel the commodity forward. Their operation is designed so that one out of every nine rollers is powered by an internal motor linked to the non-powered rollers via a series of O-rings.
These conveyors are best suited for smaller and lighter products with multiple independent conveyor segments that allow the smart functionality to start and stop as needed.
The MDR – Motor Driven Live Roller conveyor is a newer type of conveyor. It slave drives transportation rollers with small DC motors. The motor is frequently built into the roller. These small motors are spread throughout the conveyor, and each motor serves as an accumulation zone. To control the motor speed and direction, simple controller cards are used. These cards also include photo eye inputs for controlling zone accumulation.
There are numerous advantages to using MDR over traditional AC motor conveyors. MDR systems are ideal for accumulation due to their small size and distributed nature, eliminating the need for PLCs or complex pneumatic systems. When compared to line shaft conveyors, transportation rollers are slave driven, each with bands that are easily replaced. For declines, inclines, or speed changes, belts can be utilized on top of MDR rollers.
This chapter will discuss the applications and benefits of roller conveyors.
Due to their versatility and utilization, roller conveyor systems are applied widely in many industries, mainly manufacturing and logistics. The examples are the industries listed below:
Circuit design that is extremely adaptable. There are solutions for almost any situation: loads, routes, slopes, etc.
Because of the various sensors and devices, it is a very fast and safe load transport system. It lowers the likelihood of goods being broken. They can also withstand heavy loads. Conveyors are a very dependable, deep-rooted solution in the warehouse transport sector, and their value is undeniable. Its components are tough and long-lasting, so this is an excellent decision and can be repaid for years to come.
Cleaning: Despite the fact that precise solutions are designed to address this issue, the warehouse's complexity makes it difficult to clean compared to overhead conveyors.
Space Consuming: Installing conveyors, of course, limits the space available in a warehouse layout (i.e. handling equipment and operators moving through), and this must be considered.
The Occupational Safety and Health Administration (OSHA) has guidelines for the operation of conveying systems. Furthermore, the American National Standards Institute (ASNI) has safety considerations for conveyor design based on the American Society of Mechanical Engineers (ASME) guidelines. Every year, ASME and OSHA review and update these requirements to reflect new developments and technology.
Conveyor safety standards are incorporated in:
Though a conveying system may be a single machine, it is actually a system of various interacting pieces that rely on one another to function properly. To effectively maintain a conveying system and avoid problems, it is necessary to examine each individual component and how it contributes to the overall operation.
Oiling the pressure or drive screw and nut on a regular basis. These parts must be sealed with oil after a long period of time. After using the conveyor system, the drive chain and roller bearings must be oiled. It is best practice to make it a staff member's responsibility to oil these parts of the roller; this ensures that someone is at all times observing whether the system requires oiling or maintenance.
Conveyor rollers need frequent cleaning. To keep it clean and sanitary, and to avoid system blockages, any residue or debris must be wiped down from the surface. Different rollers require different cleaning methods; for instance, stainless steel rollers must be sprayed with water then washed with a detergent.
Preventative maintenance, in addition to problem-solving maintenance, is critical for conveyor system owners. This type of preventative maintenance seeks out minor issues before they become major issues. It also ensures that the workplace's system is functioning properly.
Maintenance requires examining the conveyor rollers to see if they're flexible, the drive chain or belt is worn, and the surface is level. Keeping an eye on how the rollers on the conveyor are moving, they should all be moving smoothly in the same direction. If one roller is not moving or wobbly, there is a problem that needs to be addressed. Checking the roller bearings and determining whether the problem can be fixed safely is important. If it can’t be fixed safely, contact a maintenance expert.
After running the system for a long time it is important to check the temperature of the lubricating side of the roller bearings. If the temperature is extremely high, the system must be turned off, allowed to cool, and checked for any possible problems.
Conveying systems are an important component of production and automation. Each roller conveyor system is designed to meet the needs of a specific application. Though gravity roller conveying systems are the most well-known, other types include belt driven rollers, chain driven rollers, line shaft rollers, and zero pressure rollers. Roller conveying systems, like any other type of machine, require routine maintenance. With conveying systems, safety is critical. OSHA and ASME provide regulations and guidelines for the use and design of conveying systems.
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