piezo ceramic
http://www.marco.de/D/pa/ps/007pics/D_pa_ps_pics_pic00037.jpgmarco provides piezoceramic stack actuators according to customerspecifications.The designs rely on our in-house manufacturing ofpiezoceramic materialsand our knowledge and experience in all the manufacturingtechniques: surface-finishing, plate cutting, structurized vapourmetallization and melting of metallized ceramics.
The function of a stack actuator is determined by the following parameters:
[*]Relative extension at a maximum operating field strength of2 kV/mm
The choice of a suitable material is critical, for example,piezoelectric or electrostrictive. The mechanical prestress alsoinfluences the relative length extension.
The material also determines the temperature behaviour, hysteresisand linearity characteristics of the actuator.[*]Extension of the stack
The extension depends on the relative extension of the material and onthe length of the stack. It is typically about 0.11 ... 0.18 %. Thelength of a stack should not exceed approximately 10x its diameter forcircular stacks, and10x its smaller side length for rectangular stacks.[*]Blocking Force
The blocking force of a stack element is proportional to the surface ofits crosssection. marco offers a range of disks with 10 mm, 15 mm, 25 mm,30 mm and 35 mm diameter. Other diameters are available upon request.
The range of rectangular stacks is much more varied, offeringgreater design possibilities.
The smallest possible sections are 3 mm x 3 mm, the largest 50 mm x\50 mm. The choice of section size and shape is determined by theloads/forces and the conditions of installation.[*]Operating Voltage
With the given maximum operating field strength of 2 kV/mm, the operatingvoltage is determined by the thickness of the individual plates.marco manufactures actuator stacks with plate thicknesses from 0.15 mm,which allows operating voltages from 300 V to 1000 V.[*]Electrical Capacity
The capacity of a stack element is determined by the material, the platethickness, the section and the length of the element. The actuatorcapacity is of great importance for the dynamic operation of a system.The capacity and the operating voltage can be freely adjusted byvarying the plate thickness.
Capacity values are low-signal measured values. Under operatingconditions (operating field strength and mechanical load), they canincrease up to twice the measured value.
[*]Permissible Load
We differentiate between mechanical compression load and tensile load.
The compression load depends on the surface of the section and leads toa compression of the stack as an elastic system, depending on thestack's mechanicalstiffness. The zero point of the piezo actuator displacement is thusshifted.
The maximum permissible compression load is calculated fromthe maximum permissiblecompressive stress of 40 N/mm2 and the section surface of theactuator.
The actual compression load in an application consists of the prestressload and the static and dynamic loads. It should not exceed themaximum value.
The tensile load should not exceed 80 % of the prestress load.[*]Prestress
Prestressing stack actuators has a positive effect on manyproperties, particularly in dynamic operation:
- increased external tensile load of 80% of the prestress load
- increased intrinsic stiffness
- inertia compensation in dynamic operation
- increase in extension of the materials FPM231 and FPM203Specific extension as function of mechanical compressive stress
We recommend a prestress load (Fv) with 25 N/mm2actuator cross sectional area or62.5 % of permitted compression load (Fzul.).
The stiffness of the prestress spring should not exceed 10 % of theactuator stiffness.
[*]Resonance Frequency
Resonance frequency is determined by low-signal control andfree-body conditions.Part Number Information:
pa/ps<A><B>/<C>x<D>x<E>/<F>
pa =
Piezo Actuator
ps =
Stack
<A>=
Maximum operating voltage and polarization voltage in 100V
3 =300 V
5 =500 V
10 = 1000 V
<B>=
Material Description
1= FPM 220*
2= FPM 202
3= FPM 231
4= FPM 110
5= FPM 225 Elektrostriktor RT
6= FPM 226 Elektrostriktor 50°C
7= FPM 203
* replaced by FPM 231!
<C>x<D>x<E> =
Dimensions
Height x Width x Depth
for round parts: Height x Diameter
<F>=
Version
a, b, c, ... specifies the wire length, cable type, end-piece design,etc., specified in the drawing of the particular product.
Stack actuators
marco offers complete system solutions based on customers' specificrequirements:
[*]Stack inside a housing with mechanical pre-stress and integrated positionmeasurement system for position-regulated operation[*]Highly integrated regulated positioning systems for 12 V drive voltage[*]Position translated systems[*]Drive electronics for analog and switching operation, for static to highdynamic displacements, for controlled and regulated positioning tasks.For high dynamic applications, the Torque-Block® is used. Itsadvantage over stack actuators is its longer life expectancy due tostress minimization on the tracks and the possibility of buildingtemperature compensated systems.
On request, the soldered tracks on stack actuators can be strengthened,thus permitting higher currents; inlays can be used to improve themechanical stabilityof the brittle soldering material.
The following table lists the characteristic values of several circular
stacks made of the material FPM 220 with diameters 10 mm,
15 mm, 25 mm and 35 mm:
http://www.marco.de/D/pa/ps/007pics/Z_dwg_088_08803_1.1_kata_1.gif
Type
Dimensions
Stroke
Operating
Permissible
Resonance
Capacity
d+0,5
amax
l
at Umax=1000V
Stiffness
Load
Frequency
(Typical)
[µm]
pa/ps101/16x10/a
10
12
16
20
79
2.4
78
75
pa/ps101/31x10/a
10
12
31
40
41
2.4
41
150
pa/ps101/46x10/a
10
12
46
60
27
2.4
26
225
pa/ps101/16x15/a
15
17
16
20
177
5.4
73
165
pa/ps101/31x15/a
15
17
31
40
91
5.4
38
330
pa/ps101/46x15/a
15
17
46
60
62
5.4
24
495
pa/ps101/16x25/a
25
27
16
20
491
15.0
65
460
pa/ps101/31x25/a
25
27
31
40
253
15.0
34
930
pa/ps101/46x25/a
25
27
46
60
171
15.0
21
1395
pa/ps101/16x35/a
35
37
16
20
962
30.0
49
915
pa/ps101/31x35/a
35
37
31
40
497
30.0
25
1830
pa/ps101/46x35/a
35
37
46
60
335
30.0
16
2745
The following characteristic values apply for
a choice of rectangular stacks with dimensions 3 mm x 3 mm,
4 mm x 5 mm and 8 mm x 8 mm made of the material FPM 231:
http://www.marco.de/D/pa/ps/007pics/D_pa_ps_pics_pa_qna2.gif
Stroke http://www.marco.de/pics/eqn5C282A44.gifl
Stroke http://www.marco.de/pics/eqn5C282A44.giflnom
Height l
Stiffness
Permissible
Pre-
Capacity
Resonance
at Fv
at F=0
Load
stress
Frequency
and U=300V
and U=300V
Fperm.
Fv
[µm]
[µm]
[µF]
pa/ps33/5x8x8/a
7
5
5
225
2.5
1.56
0.26
178
pa/ps33/9x8x8/a
14
10
9
125
2.5
1.56
0.52
117
pa/ps33/18x8x8/a
28
20
18
62
2.5
1.56
1.03
63
pa/ps33/26x8x8/a
42
30
26
43
2.5
1.56
1.50
45
pa/ps33/5x4x5/a
7
5
5
80
0.8
0.5
0.10
253
pa/ps33/9x4x5/a
14
10
9
45
0.8
0.5
0.19
125
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