Principle and Manufacturing Technology of Concrete Spun Pole Moulds

Two centrifugal methods manufacturing circumferential concrete poles with centrifugal spinning machines in domestic: centrifugal method of lathe type and friction roller drive. The former only make non-prestressed concrete poles and the latter can make various circumferential concrete poles such as non-prestressed concrete poles, prestressed poles, partial prestressed concrete poles and steel cylinder concrete poles.

The article only briefly introduces manufacturing, installation, maintenance and repair of concrete poles manufacturing circumferential prestressed concrete poles with friction roller method. To make circumferential prestressed concrete poles on the concrete pole spinning machines with different kinds and different length, it's essential to learn the national standard of circumferential prestressed concrete poles. The standard stipulates 19 kinds of poles and 60 specifications. The length of whole pole is 6m of short poles; the longest poles is 15m. According to the national standard (JC/T364-2001), the wheel distance of running wheel is 2m. If the whole circumferential prestressed concrete pole with 15m is produced on the centrifugal spinning machine, then 8 running wheels which are supported on the roller will be necessary. In design of steel moulds there are two structure types: one is half-opening type; another is all-opening type. The notch is existed only in one side of half-opening mold. The feature of this kind mould is no paste-leaking; the good coaxiality of concrete electric pole steel moulds; the low requirements of centrifugal spinning machines. The disadvantages are the waxing top-pushing technique during the processing of poles, so the surface of poles is not enough smooth and also one complete set of equipments of wax irrigation and wax recycle and one set of top-pushing equipments and concrete injection pump. All these cause a great investment cost. Therefore, this is not applicable to most of concrete products factories. Another is whole-opening type. The  two half are positioned with chase mortises and then integrate molds with bolts on the parting surfaces. This type is widely used by most of concrete factories. The structure of this type is as shown in picture 11-3-1.

During manufacturing the half moulds, the steel plate of 8mm is usually used in the cylinder body. As the taper ratio of taper poles in the national standard is 1:75. So the cylinder plate will be processed in the special conical mould with cold pressure.As the limitation of width of steel plate shearer, and limitation of length heat of cold pressure mould , equipments of cold working, in generally, the factory will design the pipe wall plate length 2m, and then connect with segments. In addition, as the limitation of manufacturing range of machining equipments and restriction on delivery vehicles and roads, so the length is designed among 4m, and some special will be among 5m. To ensure the steady and high-speed run and non-deformation, the supporting plate and lining board will be welded on the cylinder; the reinforcing plate should be welded on the slot-coupling, the connect flange in the segmented welding joint. The reliability of of cylinder plate of 8mm can be ensured during high speed running. So the rigidity of longitudinal and horizontal of cylinder surface should be improved. The common practice is to weld the longitudinal and horizontal ribbed plate and weld the end-plate flange which is connected with longitudinal reinforcing plate. How integrate two half moulds? According to standard of JC/T364-2001, two reinforcing plates thicker than cylinder plate will be riveted on the cylinder plate of parting surface.

One is to rigidity of horizontal end and the second is to plane the mortise on the reinforcing plates to merge into whole mould. The reinforcing plate and pipe wall plate is connected with riveting meanwhile, couples of lug bolts can be welded on the reinforcing plate. The crane rings of slinging and rolling moulds can be weled on the reinforcing plates.