Roller Conveyor Shot Blast Machine Type HD

Shot Blast Cabinet

As with all Wheelabrator roller conveyors the shot blasting cabinet is manufactured completely from manganese. Manganese has a property which is hard enough to deal with the shot blasting from 35HRC to more than 50HRC.

Therefore manganese has extremely good blasting properties. In the hot spot area of the blasting cabinet, additional 10mm thick manganese plates are added. They are attached from the outside and are easy to replace. When aggressive shot is used, additional lining of manganese-, tool steel or cast material can be provided.

To avoid shot leakage, several rubber layers or Vulkolancurtains are fitted in areas of heavy wear. These are mounted in a V-Track and are easy to replace.

Abrasive Removal Unit

After the blasting process, the workpiece may still be covered in blast media, which must be cleaned off. This task is carried out by a rotating brush, which is fitted with securely attached brush segments, which are interchangeable.

To avoid blast media building up on long parts, the rotation brushes flick the spent abrasive from the work surface into a specially designed trough which has a screw conveyor taking the media back into circulation. To keep the position between the brushes and the screw conveyor constant when blasting different sized work pieces, both are built with the same adjustable framework. The framework can be adjusted manually or automatically in intervals of less than 5mm at each required height. Finally any remaining media on the work pieces will be removed by the blow off station, which is mounted on the same framework and uses high pressure ventilators to blow off any media remaining.

Cartridge Filter Unit

During the workpiece blasting process, rust and scale, along with broken down media dust (or fines) will start to develop. The fines are separated in the abrasive cleaner, which is adjustable to the different types and sizes of blast media. The cartridge filter that produces the necessary pressure is fitted on top of the machines for the RB 600, RB 1000 and RB 1500 and it is situated next to the blasting machine for the bigger machines from RB 2000 upwards.

The impact separator within the cartridge filter unit not only ensures that the broken down fines are separated (which protects the filter cartridge against unnecessary wear) but it is also certified as a spark extinguishing device and is one of the elements that contributes towards fulfilment of ATEX regulations. The cartridge filters clean the cartridge automatically using an air pressure pulse. The intensity and duration of the pulse can be adjusted according to the type and amount of dust. All the cartridge filter processes are performed without ignition.

Loading and Unloading

In standard format, the roller conveyor inlets and outlets are powered by the central drive of the blasting machine. To increase the efficiency they can be fitted with a separate drive unit. The affiliated frequency converter is automatically synchronised.

If bowed workpieces are being blasted that cannot be cleaned properly by the brush and blow stations, then a longer collection track with a reclamation conveyor is recommended to help ensure that the blast media goes back into the machine.

Through the installation of a cross feeding system, many efficiencies can be achieved. Also with a cross feeding system incorporated, the blasting machine can be integrated into a sawmill/bore production line.

Abrasive Blast Media

For most roller conveyor installations the blast media would normally be round (cast or rounded cut wire shot). The blast media travels around the machine in a circle and is continually cleaned of contamination.

For a good blasting result a balanced mix of new and used blast media is imperative. The finer used media in this mixture is important for equal coverage of the surface being blasted and the coarser media is important to break up any scale.

The use of the correct media is of particular importance for the blasting process to ensure a good blasting result. 

The following is a useful guide:

• For coarse workpieces (e.g. heavy plate profiles) a coarse abrasive media mix (steel ball shot size S390 and over)
• Delicate workpieces (e.g. thin metal plates) a fine abrasive media mix (steel ball shot size S330 and below)