WWA-1 Indicator with Dosing Function

Our WWA-1 indicator is available with the WWC-4N relay box. This allows it to be used for simple dosing functions, target weighing (checkweighing function), and other switching operations.

In-dosing

The WWC-4N relay box is equipped with 4 potential-free relays. This means up to 4 different components can be dosed. Operation of the WWA-1 is very simple and intuitive. The user can determine whether one, two, three, or four components should be controlled. The components can be dosed automatically one after the other or started individually. An automatic overrun correction can be enabled for each component. This determines how much material has continued to flow after the valve or screw feeder was switched off. In subsequent dosing cycles, the device shuts off earlier accordingly so that the target weight is reached precisely.
An adjustable maximum weight (maximum capacity of the container) prevents overfilling. Furthermore, the system checks whether the component is actually flowing. If there is no weight increase after a certain time X while the component is switched on, the process is stopped.
Dosing can, of course, also be paused, resumed, or stopped at the touch of a button.

The following videos show various possibilities for in-dosing.

1. Dosing one component

In the video, 500kg are dosed first. Then the target value is changed to 400kg and dosed again. The dosing process is paused briefly in between.

2. Dosing three components separately

After starting, the system prompts for which of the three components is to be dosed. After selecting 1, 2, or 3, the respective dosing process begins. At the end of the video, it is shown how to change the target value for component 1 from 250kg to 200kg.

By the way, this function can be used to dose up to 4 stored weights. For example, if you have big bags that are always to be filled with 1000, 750, 500, or 250kg, you can set 1000kg for component 1, 750kg for component 2, 500kg for component 3, and 250kg for component 4 as the target value. In the relay box, you wire the system so that the same feed screw is started for all 4 components. At the device, you only need to select component 1, 2, 3, or 4, start, and 1000, 750, 500, or 250kg will be filled.

3. Dosing four components automatically in sequence

With this dosing method, 4 components are automatically dosed one after the other. At the end, it is shown again how to change the target value of a component.

Out-dosing

Out-dosing differs little from in-dosing. The target values to be dosed from a container are edited as described in the videos above. Once started, the selected weight is dosed from the full container. If the container weight falls below the weight to be dosed, the weight is displayed flashing, and the process cannot be started.

Semi-automatic filling control with the 83sigma indicator

We also implement simple dosing systems with our indicators and electronics. One example is the semi-automatic filling control. The goal is to fill a specific quantity as precisely as possible. This is often realized with a feed screw, the motor of which is controlled via a frequency converter. The screw conveys the material into a big bag, sack, or container. The big bag can, for example, hang from 4 load cells or stand on a weighbridge. Smaller sacks or containers are weighed on a weighbridge with a single-point load cell.

In our example, you can see the simple operation of such a control system with the 83sigma indicator. This requires the indicator with activated inputs and outputs and the HAS program. The outputs drive a relay card, which in turn controls the frequency converter in a small control cabinet. A push-button can be connected to one of the inputs to start the filling process. The 2nd input can be used for a quick emergency stop for safety reasons.

After starting, the HAS program (semi-automatic filling control) monitors the filling of a predefined material quantity (setpoint) for one component. If the target range (net weight between tolerance limit - and tolerance limit +) and the stable state (can be disabled) are reached during a filling process, the process is ended automatically and the outputs are deactivated. In addition to tolerance limits - and +, there is also the tolerance limit --. This determines the switchover on the frequency converter from coarse to fine flow, so that the feed screw rotates more slowly at the end of the dosing.

The 6 function keys of the 83sigma are assigned as follows by default:

• F1 = Start filling with prior entry of the target value
• F2 = Start filling with the last used target value
• F3 = Pause filling
• F4 = Resume filling
• F5 = Change target value and tolerances
• F6 = Abort

Example:

1000kg are to be filled into a big bag. The filling tolerance should be -0.5kg and +1kg, meaning the target value is between 999.5 and 1001kg. A switchover from coarse to fine flow should occur at 990kg.

First, the target value and the tolerances must be entered in the device. Press the F5 key for this. The following points are prompted:

Setpoint = 1000kg
Tolerance -- = 10kg (switchover at 990kg from coarse to fine flow)
Tolerance - = 0.5kg
Tolerance + = 1kg

Afterward, the filling can be started with the F2 key (or the button at input 1) using the previously set parameters.

With F1, the setpoint to be filled is requested first. Upon confirmation, the filling process starts directly. The tolerances used are those last set.

With F3, the process can be paused, and with F4, it can be resumed.

F6 (input 2) cancels the entire filling process.

In further settings, it can also be determined whether the device should tare before filling. If necessary, the filled weights can be totaled, printed, and/or sent to a PC. Manual post-dosing is also possible.

Under certain conditions, this system can also be used as a verified non-automatic weighing instrument. Please contact us...

If multiple components need to be filled, the 84vario with the recipe program is required.