What is the Gravimetric Control System#
The gravimetric method is the weight of the product per meter. The weight of the product can be calculated according to the size of the product and the density of the material. The constant weight per meter largely determines the quality of the product.
The Gravimetric Control System is installed on the top of the feed port of the extruder. PID closed-loop control is adopted to realize the control of tube meter weighing. In any case, at any time it can control the motor speed, traction speed and production line feed.
Why a conventional line must equip it#
| Pipe stage | Without gravimetric control system | After equipping Sealion gravimetric control |
|---|---|---|
| Booting | The pipe thickness can only be known when a long length has been output, and it needs to be adjusted many times to meet quality requirements — wasting material, time and labour. | Obtain the weight-per-metre data and display it on the screen. Shorten boot time: the operator can control and adjust the tractor speed and extruder speed, save material, improve efficiency. |
| Production process | Depends on the experience and skills of the operator; unable to monitor the production process, leading to uneven weight per metre and unpredictable deviation. | Automatically control the extruder and tractor speed by setting the meter-weight recipe. Prevent human error, monitor the weight per metre throughout, keep it constant, alarm and handle immediately when deviation appears. |
| Change material | The weight per metre is unknown with different material — this will cause a large amount of waste pipe. | No matter how the material changes, the system will check and adjust automatically. |
| Post-production tracking | Unable to track after warehousing. | Record and save for the whole process, traceability afterwards. |
Application#
Plastic pipes, films, cables and etc. — extrusion production process and quality control.
The main function#
- Shorten start-up time; solve the problem that cannot be adjusted in start-up and during production.
- Solve the problem of meter weight deviation and waste material — can save 2%–5% raw material.
- Solve the problem of pipe broken / pipe joint; control pipe meter weight and extrusion output.
- Solve the problem of uneven thickness of pipes caused by changing density and proportion of raw materials.
- Stabilize production process, control product quality.
- Solve the problem of the waste pipe caused by the blockage of the filter net.
- Statistics and save production data.
System workflow#
The Gravimetric Control System contains an intelligent scale. The function of the scale is that the small hopper opens and closes the valve continuously to cycle control the material, making sure each batch of material is free falling and keeps the same pressure. The action of opening and closing valves is controlled by microcomputer based on the following procedures strictly:
- 1The material fills the hopper; the valve closes when it reaches 80%.
- 2The material in the hopper falls down and feeds the main screw.
- 3When the material is lower than 20%, the valve opens, reloads material and proceeds to the next cycle.
Technical structure#
Installation#
Technical parameter#
| Power supply | AC220V |
| Temperature | -10~50℃ |
| Max humidity | 90%R.H 不结露 / non-condensation |
| Capacity | 10W |
| Sensor range | 10 / 20 / 30 / 50kg |
| Input sensitivity | 0.5uV/d |
| Input range | 0.2~25mV |
| A/D accuracy | 24bit |
| D/A accuracy | 12bit |
| Conversion mode | Sigma-Delta |
| A/D switching rate | 4000 次/秒 / 4000 Sec |
| Nonlinear | 0.01%F.S |
| Gain drift | 10PPM/℃ |
| Max accuracy | 1/10000 |
| Control mode | 主机控制或牵引控制 / Host or traction control |
| Control accuracy | 0.4/100 |
| Hopper capacity | 7L / 22L / 48L / 52L |
| Height | 1000mm |
| Weight | 60KG |
Double output gravimetric control system#
In view of the popular PE/PPR/PERT pipe high-speed production line, the linear speed reaches 20m/min. If you adjust the speed, the tube will be thick or thin, and pipe breakage may even occur.
The double output Gravimetric Control System controls the two extrusions according to the double traction speed and host output. It works by automatically controlling the screw speed, double traction speed and feeding rate in real time to match the setting accuracy, so as to control the pipe meter weight constantly.
Model#
Customized according to customer.
Single host gravimetric control system
| Model | Output | Size |
|---|---|---|
| MIXSCAN7 | 300 Kg/h | 404x500x726 |
| MIXSCAN22 | 500 Kg/h | 404x500x886 |
| MIXSCAN48 | 800 Kg/h | 404x500x996 |
| MIXSCAN52 | >=1000 Kg/h | 404x500x1096 |
Two host gravimetric control system
| Model | Output | Size |
|---|---|---|
| Mixscan7-7 | 300 + 300 Kg/h | 404x500x726 ×2 |
| Mixscan22-7 | 500 + 300 Kg/h | 404x500x886 / 726 |
| Mixscan48-7 | 800 + 300 Kg/h | 404x500x996 / 726 |
| Mixscan52-7 | 1000 + 300 Kg/h | 404x500x1096 / 726 |
| Mixscan22-22 | 500 + 500 Kg/h | 404x500x886 ×2 |
Three host gravimetric control system
| Model | Output | Size |
|---|---|---|
| MIXSCAN 7-7-7 | 300 ×3 Kg/h | 404x500x726 ×3 |
| MIXSCAN 22-7-7 | 500 + 300 + 300 Kg/h | 404x500x886 / 726 / 726 |
| MIXSCAN48-7-7 | 800 + 300 + 300 Kg/h | 404x500x996 / 726 / 726 |