/ep_edm/en/contect_1072.html SHINI PLASTICS TECHNOLOGIES, INC.

Special Reports

2016 Quarter 3 Issue 28

Introduction of Gram-meter Control System

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China’s plastic pipeline industry has been fast developed in recent years. The pipe products are continuously expanding in the industry, which has been seen as product won extensive recognitions everywhere. During the 10th Five-Year Plan, the fast growing of plastic pipeline industry promoted the technology progress. Numerous enterprises have gained a lot of attention on international advanced technology, new product R&D, and new technology introduction. Along with introducing of advanced equipment, they continuously strengthened the R&D input. At the same time of industry development, many problems are exposed day by day. Especially are the less variety of material, unstable quality, large variation of price, lack of special materials, bare of product quality guarantee, unreasonable product structure and production scale, poor production equipment and product quality, disordering management, lag behind of standard, specification, drawings and quota, the mismatched facility which can’t meet the development requirement. Without practical experience, it seriously restricts industry further development and quality improvement.   

The processing and production of pipe are mainly depended on extrusion of pipe material, which are finally produced through design, cooling, and cutting by auxiliary equipment. For what affects pipe quality most fundamentally is the basic molding procedure. The essence of the issue is to strictly control the gram-meter of material discharge. With proper control of gram-meter, the pipe quality is improved after extrusion, and pipe surface is even without bulge. For current technology, there’s no precise gram-meter control device in feeding system of extruder, which can’t strictly control the gram-meter of material for material discharging, resulting poor pipe quality after extrusion. 

To solve above disadvantages, the technology issue is to provide a control system for extrusion production line, which could effectively combine discharge, extrusion and towing speed to achieve proper gram-meter control of pipe, stabilize product quality and reduce material waste.   

Gram-meter is weight per meter of the pipe product. The consistency of gram meter dominantly decides whether the pipe can meet the standard or not. Weight per meter is an automatic and strict control system. Its working principle is through real-time detection the feed amount of extruder, automatically control towing speed in the production line to reach preset value, and then control the gram-meter consistency of the pipe.       

There is fluctuation of bulk density in material or even in powders. As the detection of material is in terms of weight other than volume, it only uses the gram-meter control system that can detect the fluctuation. If there’s no compensation for fluctuation, it will affect pipe material. The gravity metering used for pipe length control stabilized the extrusion process.   


At first, the gram-meter control system tests the feeding speed by lost-in-weight metering principle, and according the speed to control the rotational speed of extruder’s screw, which makes feeding speed to be inversely proportional to screw rotational speed for constant even extrusion. Then, the controller will compare this feeding speed to preset speed. The rotation speed or towing speed of extruding screw is automatically adjusted by controller. If feeding speed is higher than default value, it will automatically lower the speed of screw or increase the towing speed; If the feeding speed is lower than default value, it will automatically increase the speed of screw or lower the towing speed, finally maintains automatic adjustment of gram meter to a certain range.  

Above all, gram-meter control has crucial effect of pipe extrusion, which can reduce material input, improve production capacity and quality. The same principle can be used in extrusion process of Aluminum profile, cable, film etc, which can fulfill the function of the gram-meter control.