WWA-1 evaluation device with dosing function

Our WWA-1 evaluation device is available with the WWC-4N relay box. This means that it can also be used for simple dosing functions, for target weighing (checkweigh function) and other switching functions.

dosing

The WWC-4N relay box has 4 potential-free relays. This means that up to 4 different components can be dosed. The WWA-1 is very easy and intuitive to operate. The user can decide 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 run-on correction can be activated for each component. This determines how much has continued to run after the valve or a screw has been switched off. In the following dosings, the system is then switched off earlier accordingly so that the target weight is reached exactly.
An adjustable maximum weight (maximum capacity of the container) prevents overfilling. It also checks whether the component is actually running in. If there is no increase in weight for a period of time X with the component switched on, the process is stopped.
Of course, the dosage can also be paused, continued or stopped at the push of a button.

In the following videos we show different ways of dosing.

1. Add a component

In the video, 500kg is initially dosed. Then the target value is changed to 400kg and dosed again. The dosage is paused briefly in between.

2. Add three components separately

After starting, you will be asked which of the three components should be dosed. After selecting 1, 2 or 3, the respective dosing starts. At the end of the video, you will see how to change the target value for component 1 from 250 to 200kg.

By the way, up to 4 stored weights can be dosed with this function. For example, if you have big bags that should always 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 connect everything so that the same feed screw is started for all 4 components. On the device, you only need to select component 1, 2, 3 or 4, start it and 1000, 750, 500 or 250kg will be filled.

3. Automatically dose four components one after the other

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

dosing

Dispensing differs little from filling. The target values ​​that are to be dosed from a container are edited as described in the videos above. When you start, 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 can no longer be started.

Semi-automatic filling control with the 83sigma evaluation device

We also implement simple dosing systems with our evaluation devices and electronics. One example is the semi-automatic filling control. The aim is to fill a specific quantity as accurately as possible. This is often achieved with a feed screw whose motor is controlled by a frequency converter. The screw conveys the material into a big bag, sack or container. The big bag can, for example, hang on 4 load cells or stand on a weighing bridge. Smaller sacks or containers are weighed on a weighing bridge with a single-point load cell.

In our example, you can see the simple operation of such a control system with the 83sigma evaluation device . You need the evaluation device with activated inputs and outputs and the HAS program. The outputs control a relay card, which in turn controls the frequency converter in a small control cabinet. A button can be connected to one of the inputs to start the filling process. The second input can be used for safety reasons for a quick termination.

After starting, the HAS (semi-automatic filling control) program monitors the filling of a specified amount of material (setpoint) of a component. If the target range (net weight between tolerance limit - and tolerance limit +) and the rest position (can be switched off) are reached during a filling process, the process is automatically terminated and the outputs deactivated. In addition to the tolerance limits - and +, there is also the tolerance limit --. This determines the switching of 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 previous entry of the target value
• F2 = Start filling with the last used target value
• F3 = Pause filling
• F4 = Continue filling
• F5 = Change target value and tolerances
• F6 = Cancel

Example:

1000kg are to be filled into a big bag. The filling tolerance should be between -0.5kg and +1kg, which means the target value is between 999.5 and 1001kg. The switch from coarse to fine flow should take place at 990kg.

First, the target value and tolerances must be entered into the device. To do this, press the F5 key. The following points will be requested:

target value = 1000kg
Tolerance -- = 10kg (switching at 990kg from coarse to fine flow)
tolerance - = 0.5kg
tolerance + = 1kg

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

With F1, the target value that is to be filled is queried beforehand. Filling is started immediately upon confirmation. The tolerances that were last defined are used.

The process can be paused with F3 and continued with F4.

F6 (input 2) aborts the entire filling process.

In further settings, you can also determine whether taring should be carried out before filling. If necessary, the filled weights can be summed, printed and/or sent to the PC. Manual re-dosing is also possible.

Under certain conditions, this system can also be used as a calibrated non-automatic weighing device. Ask us...

If several components are to be filled, the 84vario with the recipe program is required.