 |
Spring Coilers Used In Compression Springs
or two point. The single point coiler is, to the best of my knowledge, used mainly in North America. The rest of the world uses two point coilers.
I personally have found that the two point coiler gives superior control on free length compared to the single point.
For example, I have had some spring makers tell me they can set up any job they need on their 25 year old mechanical Torin machines in less than 30 minutes. If that's your case…then great! If not, consider that new 2 axis CNC compression spring coilers costs less than a brand new mechanical machine. That is if you can even find a new mechanical machine. In a lot of cases it cost less than a used mechanical machine! If you are setting up jobs in under 30 minutes on a mechanical, you'll be doing them in less than 10 minutes on a 2 axis machine. Consider also that machine parts, if needed, won't be as hard to find, or as expensive, with the new 2 axis machine compared to that old mechanical. Let’s get down to basics. What advantages do CNC spring coilers have over mechanical machines? It depends on what type of machine you are looking at. Is it a two axis or 6 or more axis? If all you are making is straight compression springs you do not need anything more than 2 axis. Let’s look at what the axis normally covers –
Two axis spring coilers control the timing between the cam rotation and wire feed. For example, for the front end closure of a compression spring you would say- START ROTATION STOP ROTATION FEED
The above says feed 30mm of wire when rotating the cam shaft from 20 to 120 degrees. If you need to close up the end you can simply add wire. Change the 30mm feed to 40mm feed and leave the cam rotation numbers where they are. If you need to open up the end you can simply take out wire. Change the 30mm feed to 20mm feed and leave the cam rotation numbers where they are. A basic straight compression spring program on a two axis machine would look like this- START ROTATION STOP ROTATION FEED
Line 1 is for the front end. Line 2 is the body coils. Line 3 is for the back end. The benefits of adding the two axis to the mechanical machine enables you to make adjustments without adjusting the cams. For example, in the program above you could add or take out wire in line two and it would not affect the end closures on the spring. What are the drawbacks of a two axis machine? You still have cams. You need to initially set your pitch cams. Many machines have two types of cams for pitch.
They have what is called a “fast cam” or “shell cam” and a separate hub for standard pitch cams. For making most straight compression springs the shell cam is commonly used as it gives better free length control. The other drawback is if making taper springs you must use cams for the diameter control. Both the OD and pitch cams are on the same cam shaft. If timing between taper and pitch is an issue then it is necessary to use the standard pitch cams. 
Beyond the basic two axis spring coilers is a wide variety of options. Everything from 3 axis up to 11 axis or more. Each servo motor takes the place of a manual machine movement. (see above list) So, if you want to be totally cam free and just do all your timing with the computer you would need a minimum 4 axis machine. When you get beyond that, it is just extra “bells and whistles”. I may add, some of those extras are very nice to have. It is just a matter of what your budget can handle. For example, let’s look at this video of the movement provided by an 11 axis coiler - This machine has the following features-
The benefits of totally camless spring coilers are without limits. Setup changeovers can be done in a matter of minutes. Adjustments can be done in seconds. Setups that required custom made cams on mechanical machines are replaced with punching numbers into the computer. You can pick specific areas of the spring to adjust and only that area will be adjusted. For example, when trying to square up the ends you can break down your program to include as many steps as you wish and adjust each one individually. Another advantage a two point CNC coiler provides is the variety of cutoff options that are available. In some cases all of these options are available on the same machine. Ask your machine distributor about these when purchasing your machine.
…then the machine will automatically generate the program to make the spring. This is an excellent feature and very much a time saver. Of course, in most cases the technician will need to “tweak” the program a little to get the part exactly as he wants.
In summation keep in mind any spring coiler, be it mechanical, two axis, or 16 axis, still uses tooling! In other words, the quality of the part coming off the machine is going to be reliant on the knowledge and skill of the technician doing the setup. If the tooling is poorly made, or placed improperly the springs coming off the machine will not be good. The quality of the part is reliant more on the tooling used than the program generated. 
Another type of spring coiler is the lathe type. Just like the automatic spring coilers there are many different variations on this. From manual on up to two or three axis. The lathe coiler is used for short runs or larger springs made from larger wire. Many spring companies prefer the lathe coiler for large wire springs. In most cases the cost of the equipment is considerably less than purchasing a large automatic spring coiler. Also, in some cases, you can't buy an automatic spring coiler large enough for the wire sizes being coiled. I remember when I just started in the spring industry talking with the man running our lathe coiler. He was making large die springs on it. I asked him why they called it a "dummy winder". He said it was called that because you had to be a dummy to work with that large wire! With this style machine the wire is fed either automatically or manually into a catch on the lathe and wound around the arbor in the lathe. The cut off is either done automatically or with a hand held cutter. Some machines can do the cutoff on the center of the coil. In this case no secondary trim operation is needed. These machines are used for compression, torsion, or extension springs. In the case of extension springs the loops are put on with a secondary operation. Here's a video showing a CNC lather coiler that cuts off "on the coil". By doing this no trim operation is needed. Please, go to this page for a listing of machine makers and suppliers- Spring Machine Suppliers. Got some info you want to share? Click on our contact page and send it our way. Don't miss any updated information! Stay in touch by subscribing to Spring Makers Resource e-zine. Return from Spring Coilers to Wire Benders and Other Spring Coiling Machines
|
