jaw chucks · metal working machine

Jaw chucks for holding objects

Chuck:   A chuck is a particular kind of clamp. It is utilized in holding object with radial symmetry, for example cylinder. In lathes it holds the rotating workpiece whereas in drills and mills it holds the rotating tool.various chucks have jaws that are tightened up to hold the tool or workpiece. Often the jaws will be tightened or loosened with the help of a chuck key. Many jawed chucks are of the keyless variety, and their tightening and loosening is by hand force alone. Keyless designs offer the ease of quicker and easier chucking and unchucking. Collet chucks have collets, which are flexible. Some chucks, like magnetic chucks and vacuum chucks, are of a different variety. Instead, they may be flat against which workpieces are seized by magnetic or vacuum force.

Type Jawed chucks

1-three jaw chuck

2- four jaw chuck

2 .Self-centering : A self-centering chuck called scroll chuck, use jaws, interconnected  through a scroll gear, to hold a workpiece. Since it has three jaws, the word  3 jaw chuck  is understood by industrialist  to be known as self-centering three-jaw chuck. It is also referred as Universal chuck. These chucks are best suited to grip circular or hexagonal cross-sections when very fast, reasonably precise  centering is desired.

Sometimes this type of chuck has 4 or 6 rather than 3. More jaws grip the workpiece more securely if it is cylindrical. Four jaws are also useful for square bar work. There are also non-self-centering chucks with three jaws. Three-jaw chucks are often used on lathes and indexing heads.

2.1 drill chuck:  A drill chuck is a specific self-centering, three-jaw chuck used to hold drill bits or other rotary tools. This type of chuck is used on tools ranging from professional equipment to power drills for domestic use.

2.2 independent jaws:

In an independent-jaw chuck, each jaw can easily move independently as they mostly have four jaws, the phrase four-jaw chuck  is known by machinists to name a chuck with four independent jaws. The independence of the jaws makes these chucks ideal for (a) gripping non-circular cross sections and (b) gripping circular cross sections with extreme precision. Four-jaw chucks can never  be used for tool holding. Four-jaw chucks can be found on lathes and indexing heads. get more information at  http://www.machinedock.net/3-4-jaw-chucks

2.2.1 Spiders

A spider is a simple, inexpensive account of an independent-jaw chuck. It typically consists of a ring of metal with screw threads tapped thoroughly into it, in which screws serve as independent jaws. Spiders can serve various purposes like auxiliary features that complement the main lathe chuck:

2.3 Specialty jawed types (two-, six-, eight-jaw; other)

It is used in special purposes for e.g  holding of fragile materials, chucks are existing with six or eight jaws. These are usually of the self-centering design, and may be built to very high level of precision.Two-jaw chucks are presented and can be used with soft jaws  that can be machined to conform to a particular workpiece.

2.4 Jaw construction

Many chucks have removable jaws that let the user to restore them with new jaws soft jaws. Soft jaws are made of soft materials such as soft metal, plastic, or wood. They can be machined as desired for particular setups.

  1. collect: A collet, one sort of toss, is a sleeve with an (ordinarily) round and hollow inward surface and a conelike external surface. The collet can be crushed against a coordinating decrease such that its internal surface contracts to a marginally littler distance across, pressing the workpiece whose safe holding is craved. Frequently this is accomplished with a spring collet, made of spring steel, with one or more kerf slices along its length to permit it to grow and contract.
  2. Special Direct System (SDS):

Created by Bosch in 1975 for sledge penetrates, the SDS System utilizes a SDS Shank which is a round and hollow shank with spaces to be held by the chuck.An instrument is embedded into the hurl by squeezing in, and is secured until a different lock discharge is utilized. The revolving power is supplied through wedges that fit into a few open sections. The sledge activity really moves the bit all over inside the hurl following the bit is allowed to move a short separation. Two sprung balls fit into shut sections, permitting development whilst holding the bit. SDS depends on a device having the same shank measurement as the hurl.

  1. Chucks with both indexable positioning and indexable clamping:

Business creation machining now makes operation of increasingly propelled throws which have index able situating as well as index able clamping. Both capacities are regularly using pressurized water controlled. The clipping is frequently finished with every pair of jaws comprising of one altered jAaw and one mobile jaw specifically like propelled processing tight clamps. This technique for cinching brings the high accuracy and repeatability of such tight clamps to a tossing application. Such hurls offer the focusing exactness of conventional autonomous jaw tosses with the throwing speed and simplicity of customary three-jaw self-focusing scroll tosses. They have costly beginning expense  yet such starting expense pays for itself and afterward brings down continuous negligible expenses in business generation run situations.

  1. Magnetic

Utilized for holding ferromagnetic workpieces, an attractive throw comprises of a definitely focused changeless magnet face. Electromagnets are carried into contact with settled ferrous plates contained inside a lodging. These post pieces are regularly flush with the lodging surface. The part (workpiece) to be held structures the end of the attractive circle or way, onto those altered plates, giving a protected grapple to the workpiece.

7. Electrostatic:

Regularly utilized for holding silicon wafers amid lithography forms, an electrostatic hurl involves a metal base-plate and a slim dielectric layer; the metal base-plate is kept up at a high-voltage in respect to the wafer, thus an electrostatic power clips the wafer to it. Electrostatic tosses may have pins, or plateaus, the stature of which is incorporated into the reported dielectric thickness; an outline by Sandia National Laboratory utilizes a designed silicon-dioxide dielectric to frame the pins.

8.vaccum  :

A vacuum chuck is primarily used on non-ferrous materials like  copper, bronze, aluminium, titanium, plastics, and stone. In a vacuum hurl, air is pumped from a hole behind the workpiece, and air weight gives the holding power. Vacuum creates a hold down weight of 14.7 psi (101 kPa) adrift level, diminishing at higher rises where the climatic weight is lower. The reduction in holding weight is approximately 0.5 psi for each 1000′ above ocean level

Mounting methods

  • Mounting of drill chucks:
  • A threaded arbor may screw into the chuck body.
  • Atapered arbor may be pressed into the chuck body.

o          Removal and insertion may involve various tools or methods:

o          Methods: heating and cooling .

  • A drill chuck may have ahollow body that threads directly onto a lathe’s threaded spindle nose
  1. Mounting of large jawed chucks: A back plate with strings may screw onto a connector plate with the same nose, to be mounted on the table of processing machines . This “strung axle nose” kind of mounting was the regular strategy in the nineteenth century through 1930s. It is basic and valuable, yet the level of control of concentricity is not exactly sufficient to be idiot proof for fast, high-accuracy work. Strung axle noses are still based on new machine devices, yet just of the low-end assortment. High-capital assembling has moved far from this sort of mounting. The accurate conform (Set-True) idea is one approach to pursue high concentricity on strung shaft noses with some relative level of straightforwardness.
  1. Mounting of collet chucks:

Numerous machines that run collet hurls have committed collet-nearer setups whereby there is no backplate, and the shaft nose contains the female decrease for either the collet’s male external decrease, or a sleeve that will hold it. An empty drawbar goes back through the headstock to its rear, where a nearer system is mounted. The last permits simple, fast opening and shutting of the collet. The drawbar’s internal width decides the through-the-axle bar distance across limit of the machine. Some collet-nearer frameworks even permit opening and shutting without ceasing the shaft turn. The nearer on a manual machine is either lever-style or handwheel-style. The nearer on a CNC machine is fueled (electric, water powered, or pneumatic), and it might be controlled by different means: a foot pedal that the administrator ventures on when coveted; a line in the project (for opening and shutting under system control); or a catch on the control board.


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