1、Screwdriver 螺絲刀nIt would be very difficult to find a Chinese household that did not have at least one screwdriver. Perhaps the most ubiquitous of hand tools, the screwdriver has a long genealogy, the result of a complicated manufacturing process. Archimedes is considered to have invented the screw i

2、n the third century B.C., though his invention was designed to transfer motion (as in the continuous worm of a worm and gear assembly) rather than to fasten things together.nBy the first century B.C., large wooden screws were used in presses for producing wine and olive oil, and were turned with spi

3、kes stuck into or through a handle that resembled a modern corkscrew used for opening wine bottles, although larger. These were made of wood with a flat rather than a pointed end, and a container to hold the material being pressed.nMetal screws and nuts seem to have been used as fasteners in the fif

4、teenth century, although the heads of these screws were turned with a wrench and not a screwdriverthe screw heads were either square or hexagonal. Screws with slots in their heads were found in armor in the following century, although the design of the tool used to work the screws, the screwdriver,

5、is unknown.nThe modern screwdriver descends directly from a flat-bladed bit used in a carpenters brace circa 1750. Woodworkers were using hand screwdrivers in the early 1800s, and they became more common after 1850, when machines made the automatic production of screws possible. These early screwdri

6、vers were flat throughout the length of their shaft; the current design of a rounded bar that is flattened or shaped only at the working end makes the tool much stronger and takes advantage of the round wire used in its manufacture. The oldest and most common type of screwdriver is the slotted screw

7、driver, which fits a screw with a single slot in the head. There are perhaps thirty different types of screwdrivers available today in a variety of sizes, all with different purposes and all designed to fit into special screws.nThe second most widely used screwdriver, the Phillips, was invented in t

8、he late 1920s by Henry Phillips. Soon after its introduction, the tool posed a dilemma for its userthe head of the driver pulls away from the screw as it is fastened, or cam-out, leading to stripped screw heads and assemblies that are difficult to take apart. However, cam-out became a virtue; the sc

9、rews were meant to be driven with a power tool, and the assembler would know that the screw was completely driven when his power tool slid out of the screw head. A screw head that could accept the greater torque (turning power) of a power tool was an advantage over hand-turned, slotted screw heads.

10、Today, manufacturers are producing or gearing up production of Phillips screwdrivers that eliminate cam-out. Possible solutions (although details of some systems are company secrets) focus on the angle of the edges that fit into the Phillips screw, or using a better gripping material to coat or plat

11、e the screwdriver tip.nThe torx screwdriver, widely used for automobile repair and other applications, was designed to take the torque that a Phillips screw can while eliminating the cam-out problem. It has six edges in a star pattern on its flat point, and fits flat into the screw head. It is not u

12、nusual to find torx drivers sold in a set with slotted and Phillips screwdrivers.nOther types of screwdrivers have been designed for special uses, and a well-stocked hardware store will have slotted, Phillips, torx, Robertson (a square shaft that fits into a corresponding square cut out in the head

13、of the screw), and other more obscure types of screwdrivers. Some screwdrivers have not found a ready market, such as one that was designed to fit into special screws that have slots both on the top of the screw and on the side of the screw head, with corresponding grippers on the point of the screw

14、driver. There are so many screwdrivers and types of screws available that even a high quality of design innovation is overcome by consumer resistance to purchasing new types of screwdrivers and corresponding screws.1. Screwdrivers forms （螺絲刀式樣）Slotted 一字型;nUsing a slot in a screws head to turn it is

15、 an old idea: drawings from the 16th century show screws with slotted heads. The advantages of the slotted head are that:qmost people have a screwdriver that fits them (sort of) qworn drivers are easily reground qa new slot can easily be cut with a hacksaw. nOtherwise the slotted head is the worst s

16、crew drive system, and is generally obsolete. Some of its deficiencies:qA screwdriver does not automatically line up with the slot; it is easy to get off center. The user must keep the axis of the screwdriver aligned with the axis of the screw. qThe driver can engage the head in only two possible po

17、sitions, at 180 to each other. qThe sides of most slotted screwdriver bits are tapered. When the driver is turned it tends to be pushed up and out of the screw head. This is called “camout”. Philips 十字型nHenry F. Phillips (1890 1958) was a U.S. businessman from Portland, Oregon, has the dubious honou

18、r of having the Phillips-head screw and screwdriver. named after him.nThe importance of the crosshead screw design is its self-centering properties, useful on automated production lines which use powered screwdrivers. Phillips major contribution was in driving the crosshead concept forward to a poin

19、t where it was adopted by screwmakers and automobile companies. nThe size are:q#000 / #00 / #0 / #1 / #2 / #3 / #4Pozidriv 米字型nThe Pozidriv is a type of screw head and screwdriver, jointly patented by the Phillips Screw Company and American Screw Company, the name is thought to be an abbreviation of

20、 positive drive. It is similar in appearance to the classic Phillips cross-head, but in fact is substantially different. The largest advantage it offers is that, when used with the correct tooling in good condition, it does not cam out, allowing great torque to be applied.nThe size are:q#000 / #00 /

21、 #0 / #1 / #2 / #3 / #4Torx 星型nTORX, developed by Camcar LLC of Acument Global Technologies (formerly Camcar Textron), is the trademark for a type of screw head characterized by a 6-point star-shaped pattern (in the same way that slotted heads, Phillips, Hex, and Robertson have flat, -shaped, hexago

22、nal, and square tips, respectively). People unfamiliar with the trademark generally use the term star, as in star screwdriver or star bits. nA version known as Security TORX or Tamper Resistant TORX (often shortened by Torx TR) contains a post in the center of the head that prevents a standard TORX

23、driver from being inserted. Additionally, while a standard TORX screw may if necessary be used with a slotted screwdriver of appropriate size, this is not possible with a Security TORX. nTORX head sizes are described using the capital letter T, followed by a number. A smaller number corresponds to a

24、 smaller point-to-point dimension of the screw head. Common sizes include T10, T15 and T25, although they reach as high as T100. Only the proper driver can drive a specific head size without risk of ruining the driver or screw. The same series of TORX drivers is used to drive SAE, metric and other t

25、hread system fasteners, reducing the number of bit sizes required.Hex 六角型nThe contact surfaces of the screw or bolt are protected from external damage. nThe tool can be used with a headless screw. nThere are six contact surfaces between bolt and driver. nTorque is constrained by the length and thick

26、ness of the key. nVery small bolt heads can be accommodated. nEither end of the tool can be used to take advantage of reach or torque. Robertson 四方型n Robertson screwdriver (also called a square drive screwdriver) is a type of screwdriver with a square-shaped tip with a slight taper. Robertson screws

27、 are used mainly in Canada, but are growing in popularity around the world, as they are one of the most reliable screwdrivers.nCanadian P.L. Robertson invented the Robertson screw and screwdriver in 1908. He received a patent in 1909, and later applied for and received other patents. The last patent

28、 expired in 1964.n Close-up of Robertson driversRobertson screwdrivers are easy to use one-handed (i.e., without using the second hand to hold the screw), in fact, when driving a screw one handed, the user can let go of the driver, and the driver will stay put in the screw. They also allow for the u

29、se of angled screw drivers and trim head screws.Tri-Wing “Y”型nTri-Wing, as the name suggests, is a screw with three wings and a small triangular hole in the center. It can also be called a triangular slotted screw. A common variation is a kind in which the three wings are joined in the center (with

30、no triangular hole). Triple square 梅花型nTriple square screws are found on German vehicles such as BMW, Mercedes, and Volkswagen. In Germany they are called XZN socket screws. These screws are used in high torque applications such as cylinder head bolts and drive train components.nCommon sizes are 6,

31、8, 10, and 12mm.nOther names for triple square screws and drivers are Double Hex, Double Allen, and Aircraft Screws.Torq-Set “X”型nTORQ-SET screwdriver bits provide a precise fit in screw heads, high torque transfer and less cam-out. Spanner (一字帶口) 2. The procedure of a screwdriver （螺絲刀的主要生產(chǎn)工序）nFirst

32、, coils of wire machine-drawn to the diameter necessary for the production run; one adjustable drawing machine can produce any required diameter. In drawing, wire is fed through a die with a reducing hole until it assumes the proper size;nAfter the wire is drawn, it is annealed (heat treated) to obt

33、ain the correct tensile strength in the metal. This process involves baking the wire at a temperature of about 732 degrees Celsius for several hours. (12 hours?) nNext, the wire is straightened by a string forge and then transferred to a cold forming press, which cuts the wire to the appropriate length and forms the tip of the screwdriver and the wings that will fit into the handle.The newly formed bar (the actual screwdriver without its handle) is then heat