Screw feeders are used in various industries for the metering of material into a production process. Screw feeder design closely resembles that of a screw conveyor, but unlike a screw conveyor, a screw feeder is required to be very precise and accurate. The screw in a screw feeder is completely filled with material, compared to a screw conveyor which is typically 40-50% filled. That is part of the reason the material is accurately discharged when the feeder screw is rotating at a controlled rate.
Application Challenges
- Fast Response
Capable of accurately regulating material feed.
- Load Detection
Capable of detecting an overload or no material in the screw situation.
- Speed Range
Be able to provide the required amount of torque throughout the speed range.
- Trip-less Operation
The product must be capable of continuing to operate after a momentary power loss or a fault.
Applicable Products
Drives Products | Motion Products
| Drives Products | Features | Benefits |
| Open Loop and Closed Loop Flux Vector Motor Control
(Closed Loop only available in A1000 and G7) | Excellent speed stability and low speed torque production is possible due to Yaskawa's Flux Vector Control technology. |
| Overtorque and Undertorque Detection | Both the Overtorque and the Undertorque Detection functions can sense if there is an overloaded feeder or lack of material. |
| PID | Accurate and quick response control of material into the production process |
| Auto-Restart after momentary power loss. | Feeders can quickly restart after fault or momentary power loss. |
| Power loss Ride-Through | The material feed is not interrupted during brief power loss. |
| Torque Limit | Use of Torque Limit can prevent screw or gear damage due to excessive torque from foreign material in the load. |
| Servo and Motion Products | Features | Benefits |
| Machine control capabilities in single-axis controller | Perform auxiliary functions to help centralize process and integrate machine |
| Easy-to-use IEC61131-3 software programming environment | Minimize development time and enhance user flexibility |
| Servo position loop at 125 microsec update rate | Maximize servo control for accurate speed regulation |
| Wide range of servo monitors | Monitor torque output to aid in load detection |
| 1.6kHz speed loop frequency response | Enhanced control for improved material regulation |
| Speed range of 5000:1 | Improved control at low speed to properly drive screw across wide speed range |
| Variety of control methods with the SGDV amplifier | Integrate with a range of controllers for improved application flexibility |
Application Details
Screw feeders can generally be classified into one of two categories: volumetric or gravimetric. Both these types of feeders are required to be precise in the amount of material that is fed into the process. A volumetric feeder accomplishes its accurate feed rate by maintaining a commanded speed, which through calibration of the feeder would deliver a specific feed rate of material into the process. The screw speed can be set linearly through analog inputs or preset with digital inputs.
Gravimetric feeders, on the other hand, have more accuracy than volumetric feeders. Gravimetric feeders operate in a closed-loop system by monitoring the weight of fed material. Gravimetric feeders may monitor the material weight and feed rate and utilize the PID functionality of the Yaskawa products. The speed of the feed screw can be precisely regulated to maintain an accurate feed rate and adjust for any feed rate variations that occur.
Yaskawa drives can monitor torque to detect an undertorque or overtorque condition. An undertorque condition for a screw feeder could be an indication that the screw is not completely filled. Failing to detect this condition could provide a false indication of material that has been fed into the process and result in a bad process batch. An overtorque condition for a screw feeder could be an indication that the screw is jammed or has seized. This could result in costly damage to the feeder screw. Yaskawa A1000 or V1000 drives can be programmed to alert the operator of alarm situations or bring the feeder to a stop if required. These drives can also continue to operate through momentary power losses (< 5 ms), decreasing the chance of losing a batch of material.
Yaskawa A1000 and V1000 drives are fully capable of meeting the challenges that are faced in screw feeder applications. The drives can be mounted as standalone units or integrated into a control system for total process control.
The high-performance of the Sigma-5 servomotors makes these motors excellent options for driving the screw feeder. A wide speed range coupled with a large control bandwidth allows the servomotors to accurately and precisely control the speed of the screw in order to feed the precise amount of material for the process. Incorporating a Yaskawa motion controller can help centralize the motion control in order to maximize machine performance. The MP2600iec comes equipped with a vast array of servo monitors that allows the user to write routines for specialized functions such as load detection. In addition, the easy-to-use MotionWorks IEC programming environment allows the user to easily integrate a wide range of machine functions into one controller.
Additional Information
The pdf contains the same information as the web, but in some cases may contain more and should be used if a printed version is required.
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