Ships have shaped plates at many places, for example a curved deckhouse roof or a round bilge. Steel plates can be curved in one direction or in more directions. Using a plate roller (image 1) plates can be curved in one direction and, to a certain degree, conical as well. If a plate has to be curved in several directions then it either has to be 'upset' or formed further to the required shape using ball-peen hammers.
You can form small thin pieces of plate (such as the cover on the anchor winch in this series of photographs) on your own. For large and thicker plates a plate roller is operated by several people.
Before starting check the maximum width and thickness of the plate material that the plate roller is able to handle. This is shown on the plate roller. Attention: if you do insert thicker material into the plate roller then the rollers and the shafts will become out of alignment and the machine will be unusable.
Start from the design of the ship part for which you require a curved plate. From the design you will be able to calculate whether the plate needs to be curved in one or more directions and you will be able to determine the extent of the curvature. The easiest way is to make a jig for the plate first, using cardboard or hardboard. By using the jig you can size the required piece of steel plate and check whether it has reached the required curvature. Proceed as follows to roll a curvature in plate material:
- The plate roller consists of three rollers, of which the upper roller can be moved up and down using two spindles (image 9) on the ends of the plate roller. Rotate the spindles anti-clockwise so that the top roller rises slightly, just sufficient to allow the steel plate to be slid between the two rollers in the plate roller.
- Now first check that the top roller is parallel with the two bottom rollers. To do this you look from the centre of the rollers to the right and to the left to see whether the gap between the top roller and the bottom rollers is the same size on both sides. If necessary, adjust the height of the top roller using the spindle.
- Now place the steel plate in the centre of the rollers (image 3) and slide it in as far as possible (image 4).
- Turn the spindles on the right (image 5) and left (image 6) side by precisely the same amount so that the top roller remains parallel to the lower bottom rollers. Do this by counting the number of turns that you make on the spindle, for example a half turn.
- Now use the handle (image 12) to turn the gearwheel (image 13). The rollers start to rotate and take the steel plate along with them (image 7) and form a curvature in the plate (image 8).
- You can now turn the spindles further (attention: always turn both sides by the same amount), as a result of which the plate will be rolled with a more pronounced curvature. The large gearwheel can be turned both ways using the handle, so that the steel plate keeps going to and fro through the plate roller and becomes rolled with a greater curvature.
- Remove the steel plate from the plate roller (image 10) to check whether the correct curvature (image 11) has been achieved.
- Proceed with care and do not make the plate too curved. You can always increase the curvature by inserting the plate into the plate roller again, tightening the spindles and rolling it more. It is a lot more difficult to flatten out a deep curvature!
- If required you can continue rolling the plate until you form a 'tube'. To remove this you can remove the spindle on one side so that the 'tube' can be slid off from the top roller towards the side.
Steel plate in the centre of the plate roller...
...inserting and pressing home
Tighten the right spindle...
...and the left spindle by the same amount
Rollers take the steel plate along with them...
... and form a curve in the plate
Remove the plate from the plate roller
Check the curvature
Push the handle...