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Pneumatic vice
A vice is a mechanical screw apparatus used for holding or
clamping a work piece to allow work to be performed on it
with tools such as saws, planes, drills, mills, screwdrivers,
sandpaper, etc. Vices usually have one fixed jaw and
another, parallel, jaw which is moved towards or away from
the fixed jaw by the screw.
vice
Screw (simple machine)
A screw is a shaft with some type of helical groove or thread formed on its
surface. The threads usually engage with mating threads on the inside of a
hole in some type of appliance that the screw runs through, such as a nut.
When the shaft of the screw is turned relative to the stationary threads, the
screw moves along its axis. It is one of the six classical simple machines. A
screw can convert a rotational force (torque) to a linear force and vice versa.
The screw's pitch, the separation between adjacent threads, determines
the mechanical advantage of the machine. More threading increases the
mechanical advantage. A rough comparison of mechanical advantage can be
done by dividing the circumference of the shaft by the distance between the
threads.
Its main uses are as a threaded fastener to hold objects together, and as a
simple machine used to translate torque into linear force. It can also be
defined mechanically as an inclined plane wrapped around a shaft.
The term is also applied to devices that don't have a threaded shaft but use
the same operating principle, such as the Archimedes' screw water pump,
the corkscrew, and ship propellers.
Thread as found on a screw.
Examples
Lead screws and ball screws are specialized screws for translating

rotational to linear motion.
Automated garage doors, where a motor drives a long finely threaded

shaft at relatively fast speed and lifts the heavy door at a slower rate.

Archimedes' screw and worm gears are examples of this machine.

Other real-world examples include: fan, jar lid, cork screw, drill bit,
bolt and nut, and spiral staircase
Vise
From Wikipedia, the free encyclopedia
(Redirected from Vice (tool))
For other uses, see Vise (disambiguation).
Three types of vises
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article needs
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Please help improve this article by adding reliable references.
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A vise or vice (see American and British English spelling differences) is a
mechanical screw apparatus used for holding or clamping a work piece to
allow
work
to
be
performed
on
it
with
tools
such
as saws,planes, drills, mills, screwdrivers, sandpaper, etc. Vises usually have
one fixed jaw and another, parallel, jaw which is moved towards or away
from the fixed jaw by the screw.
Contents
[hide]

1 Types
o
1.1 Woodworking vises
o
1.2 Engineering vises
o
1.3 Others

2 See also

3 References
[edit]Types
Engineer's bench vise or fitter's vise - image inset shows soft jaws
Woodworker's vise
Without qualification, "vise" usually refers to a bench vise with flat, parallel
jaws, attached to a workbench. There are two main types: a woodworking
vise and engineer's vise. The woodworker's bench vise main characteristic is
its integration into the bench. An engineer's bench vise is usually clamped or
bolted onto the top of the bench.[1]
[edit]Woodworking vises
For woodworking, the jaws are made of wood, plastic or from metal, in the
latter case they are usually faced with wood to avoid marring the work piece.
The top edges of the jaws are typically brought flush with the bench top by
the extension of the wooden face above the top of the iron moveable jaw.
This jaw may include a dog hole to hold a bench dog. In modern metal
woodworkers' vises, a split nut is often used. The nut in which the screw
turns is in two parts so that, by means of a lever, it can be removed from the
screw and the moveable jaw can be quickly slid into a suitable position at
which point the nut is again closed onto the screw so that the vise may be
closed firmly onto the work.
[edit]Engineering vises
Machine vise - mill
Small machine vise - drill
For metalworking, the jaws are made of metal which may be hardened steel
with a coarse gripping finish. Quick change removable soft jaws are being
used more frequently to accommodate fast change-over on set-ups. They are
also kept for use where appropriate, to protect the work from damage.
Metalworking bench vises, known as engineers' or fitters' vises, are bolted
onto the top surface of the bench with the face of the fixed jaws just forward
of the front edge of the bench. The bench height should be such that the top
of the vise jaws is at or just below the elbow height of the user when
standing upright. Where several people use the one vise, this is a good guide.
The nut in which the screw turns may be split so that, by means of a lever, it
can be removed from the screw and the screw and moveable jaw quickly slid
into a suitable position at which point the nut is again closed onto the screw.
Many fitters prefer to use the greater precision available from a plain screw
vise. The vise may include other features such as a small anvil on the back
of its body.
Vise screws are usually either of an Acme thread form or a buttress thread.
Those with a quick-release nut use a buttress thread.
In high production machine work, work must be held in the same location
with great accuracy, so CNC machines may perform operations on an array
of vises. To assist this, there are several machine-shop specific vises and
vise accessories.
Hard and soft machine jaws have a very important difference between other
metalworking vise jaws. The jaws are precision ground to a very flat and
smooth surface for accuracy. These rely on mechanical pressure for
gripping, instead of a rough surface. An unskilled operator has the tendency
to over-tighten jaws, leading to part deformation and error in the finished
workpiece. The jaws themselves come in a variety of hard and soft jaw
profiles, for various work needs. One can purchase machinable soft jaws,
and mill the profile of the part into them to speed part set-up and eliminate
measurement. This is most commonly done in gang operations, discussed
below. For rectangular parts being worked at 45 degree angles, prismatic
hard jaws exist with V grooves cut into them to hold the part. Some vises
have a hydraulic or pneumatic screw, making setup not only faster, but more
accurate as human error is reduced.
For large parts, an array of regular machine vises may be set up to hold a
part that is too long for one vise to hold. The vises' fixed jaws are aligned by
means of a dial indicator so that there is a common reference plane for the
CNC machine.
For multiple parts, several options exist, and all machine vise manufacturers
have lines of vises available for high production work.

The first step is a two clamp vise, where the fixed jaw is in the center
of the vise and movable jaws ride on the same screw to the outside.

The next step up is the modular vise. Modular vises can be arranged
and bolted together in a grid, with no space between them. This allows
the greatest density of vises on a given work surface. This style vise also
comes in a two clamp variety.

Tower vises are vertical vises used in horizontal machining centers.
They have one vise per side, and come in single or dual clamping station
varieties. A dual clamping tower vise, for example, will hold eight
relatively large parts without the need for a tool change.

Tombstone fixtures follow the same theory as a tower vise.
Tombstones allow four surfaces of vises to be worked on one rotary table
pallet. A tombstone is a large, accurate, hardened block of metal that is
bolted to the CNC pallet. The surface of the tombstone has holes to
accommodate modular vises across all four faces on a pallet that can
rotate to expose those faces to the machine spindle.

New work holding fixtures are becoming available for five-axis
machining centers. These specialty vises allow the machine to work on
surfaces that would normally be obscured when mounted in a traditional
or tombstone vise setup.
[edit]Others
Other kinds of vise include:

hand vises

machine vises - drill vises (lie flat on a drill press bed). Vises of the
same general form are used also on milling machines and grinding
machines.

compound slide vises are more complex machine vises. They allow
speed and precision in the placement of the work.

cross vises, which can be adjusted using leadscrews in the X and Y
axes; these are useful if many holes need to be drilled in the same
workpiece using a drill press. Compare router table.

off-center vises

angle vises

sine vises, which use solving triangles and gauge blocks to set up a
highly accurate angle

rotary vises

diemakers' vises

table vises

pin vises (for holding thin, long cylindrical objects by one end)

jewellers' vises and by contrast

leg vises, which are attached to a bench but also supported from the
ground so as to be stable under the very heavy use imposed by a
blacksmith's work.
Solenoid
Solenoid
Magnetic field created by a solenoid (cross-sectional view)
A solenoid (1827, fr. solénoïde, gr. solen "pipe, channel" + comb. form of
gr. eidos "form, shape"[1]) is a three-dimensional coil. In physics, the
term solenoid refers to a loop of wire, often wrapped around ametallic core,
which produces a magnetic field when an electric current is passed through
it. Solenoids are important because they can create controlled magnetic
fields and can be used as electromagnets. The term solenoid refers
specifically to a magnet designed to produce a uniform magnetic field in a
volume of space (where some experiment might be carried out).
In engineering,
the
term solenoid may
also
refer
to
a
variety
of transducer devices that convert energy into linear motion. The term is also
often used to refer to a solenoid valve, which is an integrated device
containing
an
electromechanical
solenoid
which
actuates
either
a pneumatic or hydraulic valve, or a solenoid switch, which is a specific type
of relay that internally uses an electromechanical solenoid to operate an
electrical switch; for example, an automobile starter solenoid, or a linear
solenoid, which is an electromechanical solenoid.
Contents
[hide]

1 Magnetic field

2 Rotary voice coil

3 Electromechanical
solenoids

4 Pneumatic
valves
solenoid

5 Hydraulic
solenoid
valves

6 Automobile
starter
solenoid

7 See also

8 References

9 External links
Magnetic field
This is a derivation of the magnetic field around a solenoid that is long
enough so that fringe effects can be ignored. In the diagram to the right, we
immediately know that the field points in the positive z direction inside the
solenoid, and in the negative z direction outside the solenoid.
A solenoid with 3 Ampèrian loops
We see this by applying the right hand grip rule for the field around a wire.
If we wrap our right hand around a wire with the thumb pointing in the
direction of the current, the curl of the fingers shows how the field behaves.
Since we are dealing with a long solenoid, all of the components of the
magnetic field not pointing upwards cancel out by symmetry. Outside, a
similar cancellation occurs, and the field is only pointing downwards.
Now consider loop "c". By Ampère's law, we know that the line integral
of B around this loop is zero, since no current passes through it (and where it
can be assumed that the circuital electric field passing through the loop is
constant under such conditions such as a constant, or constantly changing
current through the solenoid). We have shown above that the field is
pointing upwards inside the solenoid, so the horizontal portions of loop "c"
don't contribute anything to the integral. Thus the integral up side 1 is equal
to the integral down side 2. Since we can arbitrarily change the dimensions
of the loop and get the same result, the only physical explanation is that the
integrands are actually equal, that is, the magnetic field inside the solenoid is
radially uniform. Note, though, that nothing prohibits it from varying
longitudinaly which in fact it does. A similar argument can be applied to
loop "a" to conclude that the field outside the solenoid is radially uniform or
constant. This last result, which holds strictly true only near the centre of the
solenoid where the field lines are parallel to its length, is important inasmuch
as it shows that the field outside is practically zero since the radii of the field
outside the solenoid will tend to infinity.
A solenoid with a looping magnetic field line
An intuitive argument can also be used to show that the field outside the
solenoid is actually zero. Magnetic field lines only exist as loops, they
cannot diverge from or converge to a point like electric field lines can. The
magnetic field lines go up the inside of the solenoid, so they must go down
the outside so that they can form a loop. However, the volume outside the
solenoid is much greater than the volume inside, so the density of magnetic
field lines outside is greatly reduced. Recall also that the field outside is
constant. In order for the total number of field lines to be conserved, the
field outside must go to zero as the solenoid gets longer.
Now we can consider loop "b". Take the line integral of B around the loop,
with the height of the loop set to h. The horizontal components vanish, and
the field outside is zero, so Ampère's Law gives us:
where N is the number of loops. From this we get:
This equation is for a solenoid with no core. The inclusion of a
usually metal core, such as iron, increases the magnitude of the
magnetic field of the solenoid when it is unchanged (same current,
length, number of coils). This is expressed by the formula
where μr is the relative permeability of the material that the core
is made of. μ0μr is the permeability (μ) of the core material such
that:
[edit]Rotary voice coil
This is a rotational version of a solenoid. Typically the
fixed magnet is on the outside, and the coil part moves in
an arc controlled by the current flow through the coils.
Rotary voice coils are widely employed in devices such
as disk drives.
[edit]Electromechanical solenoids
A 1920 explanation of a commercial solenoid used as an
electromechanical actuator
Electromechanical
solenoids
consist
of
an
electromagnetically inductive coil, wound around a
movable steel or iron slug (termed the armature). The coil
is shaped such that the armature can be moved in and out of
the center, altering the coil's inductance and thereby
becoming an electromagnet. The armature is used to
provide a mechanical force to some mechanism (such as
controlling a pneumatic valve). Although typically weak
over anything but very short distances, solenoids may be
controlled directly by a controller circuit, and thus have
very low reaction times.
The force applied to the armature is proportional to the
change in inductance of the coil with respect to the change
in position of the armature, and the current flowing through
the coil. The force applied to the armature will always
move the armature in a direction that increases the coil's
inductance.
The magnetic field inside a solenoid is given by:
where
henries per meter, B is the
magnetic field magnitude in teslas, n is the number of
turns per meter, I is the current in amperes, N is the
number of turns and h is the length of the solenoid in
meters. See also: Electromagnet.
Electromechanical solenoids are commonly seen in
electronic paintball
markers,pinball
machines, dot
matrix printers and fuel injectors.
Pneumatic solenoid valves
A pneumatic solenoid valve is a switch for routing air
to any pneumatic device, usually an actuator of some
kind. A solenoid consists of a balanced or easily
movable core, which channels the gas to the
appropriate port, coupled to a small linear solenoid.
The valve allows a small current applied to the
solenoid to switch a large amount of high pressure gas,
typically up to 100 psi (7 bar, 0.7 MPa, 0.7 MN/m²).
Some solenoids are capable of operating at far greater
pressures. Pneumatic solenoids may have one, two, or
three output ports, and the requisite number of vents.
The valves are commonly used to control a piston or
other linear actuator.
The pneumatic solenoid is akin to a transistor, allowing
a relatively small signal to control a large device. It is
also the interface between electronic controllers and
pneumatic systems.
[edit]Hydraulic solenoid valves
Hydraulic solenoid valves are in general similar to
pneumatic solenoid valves except that they control the
flow of hydraulic fluid (oil), often at around 3000 psi
(210
bar,
21
MPa,
21
MN/m²). Hydraulic
machinery uses solenoids to control the flow of oil to
rams or actuators to (for instance) bend sheets of
titanium
in
aerospace
manufacturing.
Solenoid-
controlled valves are often used in irrigation systems,
where a relatively weak solenoid opens and closes a
small pilot valve, which in turn activates the main
valve by applying fluid pressure to a piston or
diaphragm that is mechanically coupled to the main
valve. Solenoids are also in everyday household items
such as washing machines to control the flow and
amount of water into the drum.
Transmission solenoids control fluid flow through an
automatic transmission and are typically installed in
the transmission valve body.
Automobile starter solenoid
Main article: starter solenoid
In a car or truck, the starter solenoid is part of
an automobile starting system. Also called a starter
relay, the starter solenoid receives a largeelectric
current from the car battery and a small electric current
from the ignition switch. When the ignition switch is
turned on (i.e. when the key is turned to start the car),
the small electric current forces the starter solenoid to
close a pair of heavy contacts, thus relaying the large
electric current to the starter motor.
Starter solenoids can also be built into the starter itself,
often visible on the outside of the starter. If a starter
solenoid receives insufficient power from the battery, it
will fail to start the motor, and may produce a rapid
'clicking' or 'clacking' sound. This can be caused by a
low or dead battery, by corroded or loose connections
in the cable, or by a broken or damaged positive (red)
cable from the battery. Any of these will result in some
power to the solenoid, but not enough to hold the
heavy contacts closed, so the starter motor itself never
spins, and the engine does not start.
Pneumatic cylinder
Operation diagram of a single acting cylinder. The spring (red) can also be
outside the cylinder, attached to the item being moved.
Operation diagram of a double acting cylinder
3D animated pneumatic cylinder (CAD)
Schematic symbol for pneumatic cylinder with spring return
Pneumatic cylinders (sometimes known as air cylinders) are mechanical
devices which produce force, often in combination with movement, and are
powered by compressed gas (typically air).
To
perform
their
function,
a force by converting the potential
pneumatic
cylinders
energy ofcompressed
impart
gas into kinetic
energy. This is achieved by the compressed gas being able to
expand, without external energy input, which itself occurs due to the
pressure gradient established by the compressed gas being at a
greater pressure than the atmospheric pressure. This air expansion forces
a piston to move in the desired direction. The piston is a disc or cylinder, and
the piston rod transfers the force it develops to the object to be moved.
Contents
[hide]

1 A note about popular terminology

2 Operation
o
2.1 General
o
2.2 Fail safe mechanisms

3 Types
o
3.1 Single acting cylinders
o
3.2 Double acting cylinders
o
3.3 Other types
3.3.1 Some rodless cylinder details

3.4 Sizes
o
3.4.1 Pressure, radius, area and force relationships


4 See also

5 External links
[edit]A note about popular terminology
At least in the USA, popular usage sometimes refers to the whole assembly
of cylinder, piston, and piston rod (or more) collectively as a "piston", which
is incorrect. See, for instance, "Hydraulic piston raises the table from 19 (in.)
to 26 (in.)" Marine Tables, Inc. (Select item 3 of 8, near the bottom.)
[edit]Operation
[edit]General
Once actuated, compressed air enters into the tube at one end of the piston
and, hence, imparts force on the piston. Consequently, the piston becomes
displaced (moved) by the compressed air expanding in an attempt to
reach atmospheric pressure.
[edit]Fail safe mechanisms
Pneumatic systems are often found in settings where even rare and
brief system failure is unacceptable. In such situations locks can sometimes
serve as a safety mechanism in case of loss of air supply (or
its pressure falling) and, thus, remedy or abate any damage arising in such a
situation. Due to the leakage of air from input or output reduces the pressure
and so the desired output.
[edit]Types
Although pneumatic cylinders will vary in appearance, size and function,
they generally fall into one of the specific categories shown below. However
there are also numerous other types of pneumatic cylinder available, many
of which are designed to fulfill specific and specialised functions.
[edit]Single acting cylinders
Single acting cylinders (SAC) use the pressure imparted by compressed air
to create a driving force in one direction (usually out), and a spring to return
to the "home" position
[edit]Double acting cylinders
Double Acting Cylinders (DAC) use the force of air to move in both extend
and retract strokes. They have two ports to allow air in, one for outstroke
and one for instroke.
[edit]Other types
Although SACs and DACs are the most common types of pneumatic
cylinder, the following types are not particularly rare:

Rotary air cylinders: actuators that use air to impart a rotary motion

Rodless air cylinders: These have no piston rod. They are actuators
that use a mechanical or magnetic coupling to impart force, typically to a
table or other body that moves along the length of the cylinder body, but
does not extend beyond it.
[edit]Some rodless cylinder details
Some rodless types have a slot in the wall of the cylinder. That slot is closed
off for much of its length by two flexible metal sealing bands. The inner one
prevents air from escaping, while tho outer one protects the slot and inner
band. The piston is actually a pair of them, part of a comparatively long
assembly. They seal to the bore and inner band at both ends of the assembly.
Between the individual pistons, however, are camming surfaces that "peel
off" the bands as the whole sliding assembly moves toward the sealed
volume, and "replace" them as the assembly moves away from the other end.
Between the camming surfaces is part of the moving assembly that protrudes
through the slot to move the load. Of course, this means that the region
where the sealing bands are not in contact is at atmospheric pressure.[1]
Another type has cables (or a single cable) extending from both (or one)
end[s] of the cylinder. The cables are jacketed in plastic (nylon, in those
referred to), which provides a smooth surface that permits sealing the cables
where they pass through the ends of the cylinder. Of course, a single cable
has to be kept in tension. .[2]
Still others have magnets inside the cylinder, part of the piston assembly,
that pull along magnets outside the cylinder wall. The latter are carried by
the actuator that moves the load. The cylinder wall is thin, to ensure that the
inner and outer magnets are near each other. Multiple modern high-flux
magnet groups transmit force without disengaging or excessive resilience..[3]
1. ^ [1], (Catalog, 7.4 MB) Diagrams that show the principle are on
Pages 6 and 7 (facing pair; it's worth configuring your reader). Only
one piston is shown in the cutaway; the other is hidden; it is
symmetrical, but reversed. Parker/Origa also makes similar cylinders
with sealing bands.
2. ^ [2][3], Cable-type rodless cylinders
3. ^ [4], Commercial magnetically-coupled rodless cylinders
[edit]Sizes
Air cylinders are available in a variety of sizes and can typically range from
a small 2.5 mm air cylinder, which might be used for picking up a small
transistor or other electronic component, to 400 mm diameter air cylinders
which would impart enough force to lift a car. Some pneumatic cylinders
reach 1000 mm in diameter, and are used in place of hydraulic cylinders for
special circumstances where leaking hydraulic oil could impose an extreme
hazard.
[edit]Pressure, radius, area and force relationships
Although the diameter of the piston and the force exerted by a cylinder
are related, they are not directly proportional to one another. Additionally,
the typical mathematical relationship between the two assumes that the air
supply does not become saturated. Due to the effective cross sectional
area reduced by the area of the piston rod, the instroke force is less than the
outstroke force when both are powered pneumatically and by same supply of
compressed gas.
The relationship, between force on outstroke, pressure and radius, is as
follows:
Where:
F represents the force exerted
r represents the radius
π is pi, approximately equal to 3.14159.
p represents the pressure
This is derived from the relationship, between force,
pressure and effective cross-sectional area, which is:
With the same symbolic notation of variables as
above, but also A represents the effective cross
sectional area.
On instroke, the same relationship between force
exerted, pressure and effective cross sectional
area applies as discussed above for outstroke.
However, since the cross sectional area is less than
the piston area the relationship between force,
pressure and radius is different. The calculation
isn't more complicated though, since the effective
cross sectional area is merely that of the piston less
that of the piston rod.
For instroke, therefore, the relationship between
force exerted, pressure, radius of the piston, and
radius of the piston rod, is as follows:
Where:
F represents the force exerted
r1 represents the radius of the piston
r2 represents the radius of the piston rod
π is pi, approximately equal to 3.14159.