An inclined weighing screw conveyor requires careful consideration of conveying efficiency, screw design, drive power, and weighing accuracy. Compared with horizontal installation, inclined conveying is more likely to cause material rollback and fluctuations in feed rate. These changes can also affect the measurement results. Several factors need to be considered during equipment design and installation.
Determine the installation angle based on material properties
There is no single maximum inclination angle that applies to all weighing screw conveyors. An angle of 20° should not be treated as a universal limit. The allowable inclination depends on material flowability, angle of repose, particle size, moisture content, and required conveying capacity.
According to common engineering guidelines for screw feeders, conveying efficiency may begin to decrease when the inclination exceeds 5° from the horizontal position. U-shaped trough designs are generally used for inclinations of up to 15°. For steeper installations, a tubular housing can be considered to reduce material rollback through the clearance between the screw flight and the trough. These angles are general design references rather than fixed limits for every application.
For weighing screw conveyors, the effect of inclination on material flow stability also needs to be considered. A horizontal arrangement generally makes it easier to maintain a consistent material flow. Where higher weighing accuracy is required, the material conveying conditions and measurement requirements should be evaluated before selecting an inclined installation.
Adjust the screw flight and trough design
During inclined conveying, gravity tends to pull material back toward the lower end of the conveyor. The screw pitch and trough structure may therefore need to be adjusted to suit the operating conditions.
Compared with a standard constant-pitch screw, a shorter-pitch design can provide more flights per unit length. This can improve material support and movement along the conveyor, reducing rollback. However, a shorter pitch also changes the theoretical conveying capacity per revolution. Screw speed and actual conveying capacity must therefore be checked together.
Some screw feeder designs use variable-pitch flights. For example, a shorter pitch may be used in the inlet section, with the pitch gradually increasing along the conveyor to accommodate changes in material filling conditions.
Particle size must also be considered. An excessively short pitch may cause large particles to become trapped or obstruct the conveying passage.
Recalculate the required drive power and output torque
Inclined installation increases the power required to lift the material. The drive system must also overcome material rollback, internal friction, and any additional resistance caused by material accumulation. The motor and gearbox should not be selected directly from the drive specifications of a horizontal conveyor with otherwise similar dimensions.
The calculation should take into account the conveying capacity, bulk density, screw diameter, pitch, rotational speed, conveying length, and lifting height. These parameters are used to determine the required drive power and output torque.
Material may also move toward the lower end of the conveyor and accumulate when the equipment stops. When the conveyor starts again, the screw may be subjected to a higher starting load. The motor, gearbox, drive shaft, and coupling must therefore be selected to withstand the required torque.
Maintain a consistent and stable feed rate
The measurement results of a weighing screw conveyor are closely related to material flow conditions. Fluctuations in the feed rate or material accumulation at the inlet can change the material load inside the screw conveyor and cause variations in the weighing signal.
The feeding system should provide a continuous and uniform material supply. The feed rate must be coordinated with the screw speed and target conveying capacity. Where a vibrating feeder is used, vibration isolation is also necessary to prevent external vibration from reaching the weighing frame and load cells.
Some weighing screw feeder designs keep the material fill level near or below the screw shaft centerline to improve consistency in material movement. The appropriate fill level depends on the material flow characteristics and equipment design.
Arrange the load cells and support structure properly
During inclined installation, the support structure must carry the combined load of the conveyor body, the material inside it, and the drive components. The support frame should be designed according to the conveyor length, center of gravity, and installation angle. It must remain stable during operation, since structural deflection can affect weighing measurements.
The load cells should be positioned according to the equipment support arrangement. For example, some weighing screw conveyors use a four-point weighing arrangement, with a load cell at each support point. The load should be distributed as evenly as possible across the sensors.
Where material impact at the inlet may act directly on the load cells, the support arrangement can also be designed with a fixed pivot and two load cells to reduce the effect of feeding impact on the measurement signal.
The equipment base, support frame, and installation foundation must have sufficient rigidity to limit structural deformation caused by operating vibration and external loads. The equipment weight should be transferred through the designated weighing points. Other fixed connections should not carry part of the load, as this can cause measurement deviations.
Consider the inlet and outlet connections and sealing arrangement
The inlet and outlet of a weighing screw conveyor are usually connected to other conveying equipment or pipelines. Rigid connections can transfer additional forces to the weighing system through pipeline weight, thermal expansion, or installation misalignment. These forces may affect the load cell readings.
Suitable flexible connections should therefore be used at the inlet and outlet, depending on the equipment structure. They must maintain the required sealing performance to prevent material leakage and dust escape. The sealing arrangement should not be tightened to the point where it creates significant external forces on the weighing equipment.
The speed sensor should also be installed concentrically with the screw shaft to ensure accurate measurement of rotational speed.
After installation, the weighing system requires several checks and adjustments. These include load cell balancing, no-load zero calibration, span calibration using test weights, and testing with actual material. The weighing system parameters should then be adjusted according to the test results.
Custom machining for weighing screw conveyor components
The installation arrangement and internal structure of a weighing screw conveyor depend on the equipment specifications, material properties, and available installation space. For non-standard equipment, we can manufacture custom shafts, support housings, mounting components, and other structural parts according to customer drawings, meeting specific dimensional and assembly requirements.
Hansheng Automation also provides precision machining for components used in other industrial applications. These include functional parts for tobacco packaging and filling machinery, as well as precision structural components for yachts and RC racing cars. We support both single-piece and small-batch production based on customer-supplied engineering drawings.
