Of course, one ring of acceptable quality can be made without special equipment, but this will take a lot of time, physical effort and materials. With some special devices, bending rods into rings is faster and physically easier, but a lot of waste remains and the help of third parties is needed. We are talking about pipe benders, handicraft devices, etc. Below we will look at two devices and evaluate their capabilities.
Device No. 1
It is a rigid frame attached to a base table. A horizontal axis is attached to it on top, on one side of which there is a knob for rotation, and on the other - a multifaceted sheet.
An exemplary circle of sheet steel is welded to the outside of the sheet, reinforced from the inside with a rigid steel ring. An elongated nut with a bolt directed radially in relation to the circle is welded on one of the faces of the polyhedron.
On the frame, parallel to the upper axis, there is another axis with a rolling bearing at some distance from the reference circle and at an angle to its vertical axis.
Before starting work, place the polyhedron so that the bolt is at the bottom. We place the rod along the top of the bearing and press its end to the reference circle with a bolt. By rotating the knob, we make a semi-ring on a sample circle.
The presence of a clamping bolt does not allow bending the rod in one step. It is necessary to release the bolt, rotate the semi-ring in a sample circle, tighten the bolt again and bring the bend of the rod to a full circle.
The disadvantages of this device are associated with the duration of the bending process and large losses of metal. It is clearly not suitable for mass production of rings.
Device No. 2
The design of the second device for bending rods into rings is noticeably simpler. It consists of a steel sheet, on one side of which a small section of a profile square pipe 20x20 mm is welded for fastening in a vice, and on the other - 2/3 of a full ring made of steel strip. Also, at one of the bases of the incomplete ring, a stop-stop made of a square rod is welded on the outside at a distance of 12 mm.
Additionally, you need to stock up on two metal plastics with a thickness of 2 and 4 mm in order to work with rods not only 12, but also 10 and 8 mm, which are inserted between the rod and the limiter.
Working with such a device is quite simple. Take, for example, a rod with a diameter of 10 mm, the end of which is placed between the fragment of the ring and the stop, not forgetting to insert a plate 2 mm thick.
We grab the end of the rod with our hand and roll it around the incomplete sample ring to the end and get a half ring. We turn the workpiece over to the other side, secure it and also roll it around 2/3 of the full ring.
In order not to waste a lot of effort, at the last stage of bending we use a fork-lever and screw the ring to the end.As you can see, the ends of the ring are practically without creases. The ends of a rod bent into a ring cut off in the middle of the overlap. We weld the joint and the ring is completely ready.
To make a ring with a diameter of 30 cm, we take a workpiece with a length of L = π × d = 3.14 × 30 = 94.2 cm or, rounding, 100 cm. The manufacturing time for two rings is no more than 1 minute.
