Compression Springs are by far the most common type of spring and account for approximately eighty per cent of our production, therefore I am going to give you a brief description of three of our manufacturing methods of compression springs.
When dealing with large batch quantities, auto-coilers are the machines used to coil the springs. The picture below shows two views from the front of the auto coiler.
The four large rollers on the front of the machine work in pairs and force the wire through the wire guide tubes towards the coiling points as shown in the blown up picture on the right.
There are two grooved coiling points, one vertical and one horizontal from the right hand side of the machine which are positioned round a half round mandrel. The four large wire feeders force the wire through the coiling points which in turn force the wire round the mandrel thus giving you the required spring coils.
The number of coils can be adjusted by the amount of wire feed and the pitch spacing and the free length of the spring is governed by the spacing tool just visible on the right hand picture at the twenty past position. When the spring is finished being coiled it is cut of by the cutting tool showing on the left.
For the smaller batch sizes and particularly when using thicker wire sizes we use the semi automatic Maxi Coil machines. These have the advantage of being set up very quickly and although the springs are coiled one at once, they are automatic in the sense that all the coiling operations are controlled by compressed air.
The Maxi coil basically comprises of a large chuck in which various sizes of mandrel are fitted depending on the the required diameter of the spring. There is then a large travelling attachment to which is fastened the wire feed tool and the compressed air spacer. The wire is fed under the plate shown at the front of the machine and is passed under a peg fastened to the chuck.
When the chuck is set in motion by depressing the front handle, the wire is pulled round the mandrel thereby
forming a spring. The pitch is applied by the spacer at the back of the
traveller which automatically comes out on its
own powered by compressed air and then returns when the required number of coils have been turned. The spring is
then cut off and the procedure repeated for the next spring. Although this takes more time than automatic coiling,
its advantage lies in the very quick setting up time required. Small batches of springs can be set up, coiled and
finished while an automatic is still being set up.
When really small quantities of springs are required in reasonably small wire sizes, then Carlson hand coilers are used. These coilers work in a similar way to the maxi coilers but are only very small machines and depend on the operator turning a handle to produce the springs and the pitch is applied mechanically, not by compressed air.
Again we have a chuck and mandrel arrangement with a peg for catching the wire. The wire is fed in through a tube as can be seen on the right hand picture. The handle is manually turned and again the wire is formed round the mandrel. This time however the pitch and length is obtained by the traveller resting on the long angled bar at the front of the machine which pushes the traveller thus giving the spring a pitch equal to the angle that the bar is set, so the greater the angle the longer the spring.
Which ever method is used to produce compression springs, the last operation is common to all of them and that is the flattening of the ends so that they will stand up straight and square.
In the majority of cases this grinding flat of the ends is done on an automatic grinding machine as pictured below. These machines consist of a round plate into which bushes are fitted. The bushesinside diameter is of a size so that the springs will fit leaving a small amount of spring protruding top and bottom. The plate then turns slowly round so that the bushes plus springs pass in between either one pair of grinding wheels or as in the illustrated photograph, two pairs of grinding wheels depending on what type of machine is used. the grinding wheels grind the ends of the springs flat and square and then they drop into a waiting box for inspection when they are thoroughly tested to make sure they comply both dimensionally and in their load requirements.
This is a very simplified insight into the manufacture of compression springs to try and give you at least some idea of how springs are made. It takes, however, many years to become a competent fully qualified spring maker. If you have any questions regarding spring making do not hesitate to contact us at our email address.
