Precision requirements of linear rod rail in different transportation scenarios

Precision requirements of linear rod rail in different transportation scenarios

The accuracy requirements of linear rod rail directly depend on the characteristics of goods in transportation scenarios (weight, size, fragility), the movement mode (high speed and high frequency / low speed and heavy load) and the operation objectives (accurate docking / stable handling). Different transportation scenarios of the core needs of the differences, resulting in its linear guide precision indicators (such as guiding accuracy, repeat positioning accuracy, smooth operation) requirements are significantly different. The following typical scenarios are categorized according to the description:

First, e-commerce logistics sorting scenarios: high-frequency light load, the need for high repetitive positioning accuracy

1. Scenario characteristics: handling small goods (0.1-5kg, such as courier parcels, e-commerce commodities), the equipment to high-speed (30-60 times / min) to complete the "scanning - sorting - transplanting" action, the need for accurate docking sorting port, scanning device or It is necessary to accurately connect with the sorting port, code scanning device or conveyor belt to avoid misclassification, omission or collision of goods.

2. Accuracy Requirements:

Repeat Positioning Accuracy: ≤±0.1mm. Sorting mechanism (e.g. the slider of the pendulum sorter and cross-belt sorter) should be accurately parked at the preset position after each start and stop to ensure that the goods can accurately fall into the corresponding sorting compartments (the compartment spacing is usually only 10-20cm), and any deviation of more than 0.3mm may result in the goods getting stuck in the edges of the compartments or falling into the wrong channel.

Guiding accuracy: straightness error ≤ 0.05mm / m (short stroke, single-section guide rail length 1-3m), parallelism ≤ 0.03mm / 500mm, due to the movement of short stroke, fast speed (instantaneous speed of 1-2m / s), need to avoid the guide rail trace offset caused by the goods "fling", affecting the scanning code recognition (scanning code lens) (Focusing accuracy should be ≤ ± 0.5mm).

Smoothness of operation: vibration acceleration ≤ 0.5g (g is the acceleration of gravity), to avoid high-frequency vibration leading to cargo slippage (such as light packaging of clothing, documents).

Second, the port container transport scenarios: heavy loads and long travel, long-distance guiding accuracy is required

1. Scene characteristics: handling of ultra-heavy cargo (20-40 tons of containers), equipment (such as the shore bridge, the field bridge of the panning mechanism, container handling robots) movement stroke is long (a single section of the guide rail 5-20m), need to be along the fixed trajectory of the panning or lifting, the core is to avoid collision due to the offset of the guide rail resulting in containers and lifting tools and racks (the). The core is to avoid the collision of containers with spreaders and shelves due to the deviation of the guide rail (the container docking gap is usually only 5-10cm).

2. Precision requirements:

guide accuracy (long travel straightness): full travel straightness error ≤ 0.1mm / m (cumulative error ≤ 2mm / 20m), and need to control the "convex / concave" trend (to avoid the two ends of the high, low in the middle of the container caused by the tilt). Parallelism error ≤ 0.05mm/m (double guide rail spacing error), to prevent the spreader from twisting due to the height difference between the two sides of the guide rails, resulting in unstable container lifting.

Repeat positioning accuracy: ≤±1mm, due to the large size of the container (length 12m, width 2.4m), small positioning deviation can be compensated by the spreader's fine-tuning mechanism, no need to be too high precision, but need to ensure that the "approximate range" of each stop is the same (e.g., aligned with the truck chassis of the placement area).

Anti-biased load accuracy: in the container center of gravity offset (such as one side of the load bias), the guide rail needs to maintain the stability of the guide, lateral offset ≤ 0.5mm / m, to avoid the trajectory due to biased load "drift".

Third, automated three-dimensional warehouse scenarios: multi-storey shelves docking, high vertical and horizontal guiding accuracy

1. Scenario characteristics: stacker cranes shuttle between high-level shelves (10-30m high), completing the action of "picking up - lifting - panning - putting away", the goods are mostly pallets (50-500kg), and need to accurately docking racking spaces (spaces). The goods are mostly pallets (50-500kg), which need to be accurately docked to the shelves (the width of the shelves is usually 5-10cm wider than that of the pallets), so as to prevent the pallets from jamming or the goods from falling.

2. Precision requirements:

Horizontal guiding accuracy: Straightness ≤ 0.03mm/m in the translation direction (3-5m for a single rail), parallelism ≤ 0.02mm/500mm, to ensure that the stacker forks are inserted accurately into the bottom of the pallet along the horizontal direction (the insertion gap is only 2-3cm).

Vertical guiding accuracy (lifting direction): straightness of column guide rail ≤0.05mm/m (30m high cumulative error ≤1.5mm), avoiding tilting of the lifting platform leading to friction between the pallet and the shelf layer plate.

Repeat positioning accuracy: ≤±0.5mm (horizontal), ≤±1mm (vertical). As the distance between the shelves is fixed (usually 5-10cm higher than the pallet), the positioning deviation in the vertical direction will cause the pallet to hit the shelves; in the horizontal direction, it is necessary to ensure that the forks are completely inserted into the pallet, and the deviation will cause deformation of the side of the pallet by force.

Cold Chain Transportation Scenario: Stable Accuracy Maintenance in Low Temperature Environment

1. Scenario characteristics: transportation of frozen food (-18℃ to -30℃), equipment such as cold chain sorting line, automated cold storage handling robot, need to run for a long time in low temperature, guide rail easy to temperature contraction, grease solidification affect the stability of precision.

2. Precision requirements:

low-temperature guiding accuracy: straightness at room temperature ≤ 0.04mm / m, low temperature (-30 ℃) under the attenuation of precision ≤ 20% (i.e., ≤ 0.05mm / m), to avoid changes in the gap due to the shrinkage of materials lead to the guide rail and slider with gap (the normal gap of 0.01-0.03mm, the need to control the low-temperature in the 0.05mm, to prevent the jamming).

Repeat positioning accuracy: ≤ ± 0.2mm (low temperature environment). Since cold chain goods are mostly sealed packages, slight deviation may lead to failure of code scanning (barcode position deviation needs to be ≤1mm), but the response of mechanical parts slows down under low temperature, and the precision requirement is slightly higher than that of normal temperature sorting, and the temperature effect needs to be offset by pre-tightening design (e.g., interference fit of the slider).

Five. Heavy industrial transportation scenarios (such as automobile assembly lines, mining equipment): the accuracy of the foundation guidance under heavy loads

1. Scene characteristics: transportation of heavy workpieces (5-50 tons, such as automobile chassis, mining ore), equipment running at a low speed (0.1-0.5m/s), stable handling as the core, the accuracy requirements are subordinate to the load capacity, allowing a certain degree of deviation.

2. Precision requirements:

guide accuracy: straightness ≤ 0.1mm / m (long stroke 10-20m cumulative error ≤ 2mm), parallelism ≤ 0.1mm/500mm. Due to the large size of the workpiece (such as car chassis length 5-6m), a small offset does not affect the docking (assembly line positioning pins can be compensated for the deviation of ± 2mm), focusing on avoiding the deformation of the guide rail caused by the tilting of the workpiece (tilting angle of ≤ 0.5°).

Repeat positioning accuracy: ≤ ± 0.5mm. Docking of heavy workpieces relies on workpiece positioning rather than absolute accuracy of the guide rail, which only needs to ensure that it is "roughly in place", and subsequent correction of the deviation through mechanical limit.

Sixth, AGV automatic guidance scenarios (such as goods transfer in the park): dynamic trajectory accuracy under flexible paths

1. Scene characteristics: AGV traveling along the ground guideway or magnetic navigation path, transportation of medium-weight goods (100-1000kg, such as factory materials, hospital drugs), the need to adapt to complex paths (turning, climbing), to avoid collision with obstacles or other AGV.

2. Accuracy requirements:

Trajectory following accuracy: deviation along the preset path ≤ ± 5mm (straight line section), ≤ ± 10mm (turning section). Since AGVs are usually equipped with LIDAR or vision sensors to assist in obstacle avoidance, the accuracy of the guideway need not be too high, but it is necessary to ensure smooth movement (when the speed is 1-3m/s, the trajectory fluctuation caused by vibration is ≤±2mm).

Docking positioning accuracy: when docking station or conveyor belt, repeat positioning deviation ≤ ± 1mm (light load AGV, such as e-commerce park), ≤ ± 3mm (heavy load AGV, such as factory material truck), to ensure that the goods can be transferred smoothly (docking gap is usually 5-10mm).

In short, the essence of the difference in accuracy requirements of linear rod rail is "the tolerance of the scene to the 'accuracy tolerance rate'": handling small, high-frequency, precision docking scenarios (e.g., sorting, warehousing) is demanding; handling heavy-duty, large-size, can be correct the deviation through other ways of the scene (such as heavy transportation, ports) then the accuracy requirements are relaxed, pay more attention to the stability and load capacity.

Contact Us
📞 Phone: +86-8613116375959
📧 Email: 741097243@qq.com
🌐 Official website: https://www.automation-js.com/