Suitable equipment is essential to produce PTFE wire and cable. At present, there are mainly two types: mechanical type driven by screw rod and hydraulic type driven by hydraulic pressure, these two types each have advantages and disadvantages.
PTFE is a plastic that is almost difficult to process, so the equipment is critical. If you must produce MIL-grade PTFE extrusion lines, such as RG178, RG179, RG316, RG142, G401, RG402, RG405, etc., suitable equipment is essential. At present, there are mainly two types in the world: mechanical type driven by screw rod and hydraulic type driven by hydraulic pressure; the two types of PTFE pushers on the market each have advantages and disadvantages:
(1) Screw push
This is currently the most common. The screw is also divided into sliding screw and ball screw. If you want to make a coaxial cable, because the sliding screw has the fatal disadvantage of low-speed crawling, the pushing is unstable, and it is not recommended. The ball screw does not have this problem, but because the ball contact area is limited, there is a serious wear life problem under large pressure. This way is not suitable for the method of large compression ratio, that is, when making a wire, especially for a large length The thin-walled line is even better at it! Due to the limitation of the screw length and accuracy (and other restrictions such as mandrels), the length of the pusher is not long. At present, the most common seems to be 1.5 meters! Advantages: Under the circumstance of avoiding the problem of crawling and high pressure abrasion, the screw has the advantages of stable transmission and low price, which is the main method of domestic PTFE equipment at present. The pushing direction is mainly vertical upwards, and some are made horizontally. Self-summary with a soft mouth: [Domestic production is mechanical, relatively mature, but because it is open-loop and uncontrolled, the principles and actual equipment structure are very old, basically 30-40 years The previous old structure has the disadvantages of low pushing force (10-20T), low efficiency, slow speed, short production length, and the gradual wear of the screw rod will have a significant impact on VSWR. The advantage is that the price is low.
(2) Hydraulic push
The method represented by JENNINGS in the United States uses digitally controlled proportional valves to achieve precise hydraulic flow control to achieve stable pushing speed. Because the hydraulic method is used, the pushing force is very large and can reach the level of 100 tons. In this way, a large compression ratio wire is easy to achieve, and because the horizontal push is used, the cylinder can be made very long (to 108 inches = 2.7 meters), because the sintering part uses front traction fumigation, so the speed of extrusion and sintering fast! high productivity. Disadvantages: Because localization is not achieved, the price of the machine is high! Moreover, the maintenance of the hydraulic pressure is also troublesome. If it is not done well, there will be a problem of oil leakage. I hope that domestic equipment manufacturers will make a breakthrough in this regard. Self-summary with a soft mouth: [foreign is basically hydraulic, because closed-loop control is used, and the hydraulic force is large (up to 100T), so the production efficiency is high and the production length is long (3-4 times), And the quality is stable (such as wire diameter fluctuation, VSWR index, etc.) and it is fully computer controlled, which is a good choice for modern production!
(3) Electro-hydraulic drive
This is the most cutting-edge technology at present, and it is also a development direction of hydraulics. It also has the advantages of large hydraulic thrust and stable transmission of the screw rod. It has not been applied to PTFE pushers at present, but it has only begun to be applied on some high-end military equipment.
Post time: Jul-10-2018