HOW TO MAKE SPRINGS.docx

1、HOW TO MAKE SPRINGSHOW TO MAKE SPRINGSThere are three things youll need to read before you get started. First, the DISCLAIMER: This document is designed to provide information in regard to the subject matter being covered. Every effort has been made to ensure the accuracy of its contents. However th

2、ere may be mistakes, both typographical and in content. Additionally, work in the metal trades implies an acceptance of the risk of injury, loss, or damage, the cause of which is clearly beyond the control of the writer of a work on the subject. Therefore, the author of this document accepts no resp

3、onsibility or liability whatsoever for any injury, loss or damage sustained by a reader who, having read this material, then seeks to apply what he or she has learned therein. Please read the Terms of Use.Second, before you start to work with spring wire, read the section on safety. When you have re

4、ad that section, read it again. No kidding. And third, about this document: Ive tried to write for the benefit of someone who has (or can gain access to) basic hand and power tools. The sections of the document are arranged in logical order presuming a minimal knowledge of the metalworking trades in

5、 general or of springmaking in particular, and cross-linked to provide a forward path that leads from this point through the entire manufacturing process. Theres a glossary of spring terminology and an addendum, which should help you to define terms and find additional resources. Where possible, Ive

6、 indicated where to find additional information in the main body of the text. Most of the current material relating to the subject is written for mechanical engineers, but there are some other writeups Ive heard of, too - see the addendum for links to these. In its first incarnation, this site was m

7、ade in frames. In the second, I did away with the frames for the sake of design simplicity. My apologies to anyone who linked to frameset. The other new addition is the site map, which will give you a birds-eye view of the whole shebang. This is now the third incarnation and except for freshening th

8、e links from time to time, I consider it done. If you want to have it as a handy reference, feel free to download the zipped version. Lastly, the text itself is of very limited use without the graphics, and there is no text-only version of this site. So if youve got your graphics turned off, turn em

9、 on, OK? Any comments or suggestions for improvement should be made to yours truly. INTRODUCTIONThis section will give you some basic information about springs, what they look like, what their parts are, and how they work. If you already know about springs and want to get right to it, be my guest. T

10、here are three basic types of springs: Compression springs can be found in ballpoint pens, pogo sticks, and the valve assemblies of gasoline engines. When you put a load on the spring, making it shorter, it pushes back against the load and tries to get back to its original length.Extension springs a

11、re found in garage door assemblies, vise-grip pliers, and carburetors. They are attached at both ends, and when the things they are attached to move apart, the spring tries to bring them together again.Torsion springs can be found on clipboards, underneath swing-down tailgates, and, again, in car en

12、gines. The ends of torsion springs are attached to other things, and when those things rotate around the center of the spring, the spring tries to push them back to their original position.See the Glossary for detailed diagrams of these types of springs. Forward to Spring DesignSPRING DESIGNIf youre

13、 trying to make a spring to replace a broken one, you dont need to know a whole lot about design. On the other hand, if youre making a prototype of a machine, for instance, and you dont know exactly what you want, then this page is for you. Here youll learn some basic data about spring design, which

14、 is what youll need to know to make exactly the spring you want. General principles Mathematics Design limitations Buying design General PrinciplesThere are three basic principles in spring design: The heavier the wire, the stronger the spring. The smaller the coil, the stronger the spring. The more

15、 active coils, the less load you will have to apply in order to get it to move a certain distance. Based on these general principles, you now know what to do to change the properties of a spring you already have. For instance, if you want to make automotive valve springs a little stronger than stock

16、, you can a) go to a slightly heavier wire and keep the dimensions and coil count the same, b) decrease the diameter of the spring, keeping the wire size and coil count the same, or c) decrease the number of active coils, keeping the wire size and spring diameter the same. Naturally, you can also go

17、 to a stronger material to achieve the same result. Now, what if youre making a spring from scratch, with nothing to go on in the way of a sample? You can engineer your own design (see the next section of this page for the math), coil a spring, and then test it. If its what you want, fine. If its, l

18、ets say, a skosh too strong, then you can a) go to a lighter wire, b) open up the coil diameter, or c) increase the number of active coils to get a slightly weaker spring. Or, if you want to make things really simple, go to the Addendum, where youll find a few websites that offer online design! Math

19、ematicsNaturally, spring design software is available - you can find out where to get it in the Addendum. For the purists (or those who dont want to pay for a program), heres a very short summary of the mathematics of spring design. These equations, by the way, are taken from The New American Machin

20、ists Handbook, published by McGraw-Hill Book Company, Inc.in 1955. I dont pretend to understand them. Theres a lot more in the way of engineering that goes into spring design: these are only the basic equations. If youre interested, you can contact someone who makes spring design software or (gasp!)

21、 find it in the library under Dewey classification number 621.824. You can also contact the Spring Manufacturers Institute: they make a handy-dandy spring calculator, suitable for simple design work, that anyone can learn to use. They also have spring design software, training classes, and a bunch m

22、ore stuff. Dave sez, Check it out. Design LimitationsDepending on what kind of spring you want to design, and depending on where it will be used, your design will be limited: For all springs: A spring under load is stressed. If you put too much stress on a spring, its shape will deform and it will n

23、ot return to its original dimensions. The material from which the spring is made will have an effect on the strength of the spring: it will also have an effect on how much stress the spring will withstand. The section on spring materials will tell you more about this. When you heat spring wire (whic

24、h you always do), it may change its dimensions. Again, the section on materials will tell you more about this. For compression springs: If the spring will set solid (compress all the way, so that all the coils touch each other) at the limit of its travel, the diameter of the wire times the number of

25、 coils cannot be greater than the space allowed, unless you want the spring itself to act as a mechanical stop to the motion. Springs that operate in a high-temperature environment (like for instance inside an engine) will need to be made slightly longer to compensate for the fact that the heat may

26、have an effect on the length of the spring. The section on finishing will tell you more about this. As a compression spring assumes a load and shortens, the diameter of the active coils will increase. This is only a problem when the spring has to work in a confined space. For extension springs: Ther

27、e should be some mechanical limit on how far the spring will extend, or the spring will lose its shape and not return to its initial condition with all coils closed. Extension springs operating in a high-temperature environment may have to be coiled extra-tight, as the heat will tend to weaken the s

28、pring. The section on extension springs will tell you more about this. For torsion springs: When a torsion springs assumes a load, the diameter of the coil body will decrease. If the spring has something inside the coil, it will act as a mechanical stop to the action of the spring. Buying DesignIf y

29、ou want to have a mechanical engineer design your spring, your best bet is to call a spring shop. You can find spring shops in the phone book. If your phone book doesnt list any, go to the library: they should have phone books for major cities where spring factories are - try Detroit or Los Angeles

30、if there are none in your area. A spring shop will generally do the design work for you for a small charge. They will also try to get you to let them make the spring for you, which you may or may not want. The section on spring shops will tell you more about how their business operates. The addendum

31、 will give you links to spring shops, suppliers, people who make spring design software, and a whole slew of other stuff.SPRING MATERIALSThis section will tell you about the different kinds of material that springs are made out of. It will also tell you where to get your wire - make sure you read th

32、e Safety section so you know how to handle it safely once youve got it. Types of wire Buying wire Types of WireSprings are usually made from alloys of steel. The most common spring steels are music wire, oil tempered wire, chrome silicon, chrome vanadium, and 302 and 17-7 stainless. Other materials can also be formed into springs, depending on the characteristics needed. Some of the more common of these exotic metals include beryllium copper, phosphor bronze, Inconel, Monel, and