Appendix 3. Selection. Mitsubishi Electric MDS-C1 Series
Mitsubishi Electric MDS-C1 Series is a numerical control unit known for its AC servo and spindle drive capabilities. This industrial-grade device seamlessly integrates with various machine tools, empowering users with precise control over their operations. To ensure optimal performance and safety, it comes with a comprehensive instruction manual guiding users through installation, operation, maintenance, and inspection procedures.
Advertisement
Advertisement
Appendix 3. Selection
Appendix 3-1 Selecting the servomotor series.......................................................................................A3-2
Appendix 3-1-1 Motor series characteristics ......................................................................................A3-2
Appendix 3-1-2 Servomotor precision ................................................................................................A3-3
Appendix 3-2 Selection of servomotor capacity .....................................................................................A3-4
Appendix 3-2-1 Load inertia ratio........................................................................................................A3-4
Appendix 3-2-2 Short time characteristics..........................................................................................A3-4
Appendix 3-2-3 Continuous characteristics ........................................................................................A3-5
Appendix 3-3 Example of servo selection ..............................................................................................A3-7
Appendix 3-3-1 Motor selection calculation........................................................................................A3-7
Appendix 3-3-2 Servo selection results ............................................................................................A3-10
Appendix 3-3-3 Motor shaft conversion load torque.........................................................................A3-11
Appendix 3-3-4 Expressions for load inertia calculation...................................................................A3-12
Appendix 3-4 Selecting the power supply ............................................................................................A3-13
Appendix 3-4-1 Selecting according to the continuous rated capacity.............................................A3-13
Appendix 3-4-2 Selection with maximum momentary capacity ........................................................A3-15
Appendix 3-4-3 Selection example ...................................................................................................A3-16
A3 - 1
Appendix 3. Selection
Appendix 3-1 Selecting the servomotor series
Appendix 3-1-1 Motor series characteristics
The servomotor series is categorized according to purpose, motor inertia size, and detector resolution.
Select the motor series that matches the purpose of the machine to be installed.
Motor series characteristics
Motor series
HC
Capacity (rated speed)
0.5 to 9.0kW (2000r/min)
0.5 to 7.0kW (3000r/min)
HC R 1.0 to 5.0kW (3000r/min)
Detector resolution
1,000,000 p/rev
/100,000 p/rev
1,000,000 p/rev
/100,000 p/rev
HA N 0.05 to 0.45kW (3000r/min) 1,000,000 p/rev
/100,000 p/rev
HA-LF 11 to 15kW (2000r/min) 1,000,000 p/rev
/100,000 p/rev
Features
This is a motor for NC machine tool feed axes. It has smooth torque characteristics and is compatible with high resolution detectors. It has the same shaft shape and flange size as conventional HA motors (HA N), but with shorter L dimensions, designing machine becomes easier. It is drip-proofed against cutting oil entering the unit, and it clears IP65 specifications for environmental resistance performance as a standard.
This is the standard HC motor made into a low inertia motor. It has a high output, compact design, and is suitable for high speed driving of light loads such as loaders. The detector has been made compatible with the feed axis. It is drip-proofed against cutting oil entering the unit, and it clears IP65 specifications for environmental resistance performance as a standard.
This is a motor for conventional NC machine tool feed axes. This motor is used for the small capacity feed axes of which no HC motor capacity being set.
This is a motor for NC machine tool large capacity feed axes.
Select the HA-LF Series when the HC motor capacity range is exceeded.
A3 - 2
Appendix 3. Selection
Appendix 3-1-2 Servomotor precision
The control precision of the servomotor is determined by the detector resolution, motor characteristics and parameter adjustment. This section examines the following four types of servomotor control precision when the servo parameters are adjusted. When selecting a servo, confirm that these types of precision satisfy the machine specifications before determining the servomotor series. precision:
This value is determined by the motor detector precision, and is the value obtained by dividing the movement amount (
∆
S) per motor rotation by the detector resolution (RNG).
(2) Positioning precision :
∆ε p
This is the precision outline that affects the machine targeted for positioning, and expresses the machine's positioning precision.
When the motor is a single unit, this is determined by the detector resolution and matches with the theoretic precision
∆ε p. When the motor is actually installed on a machine, the positioning precision
∆ε p becomes 1 to 2 times the theoretic precision
∆ε
. This is due to the effect on the motor control by the machine rigidity, etc. Furthermore, the value to which the error from the motor shaft to the machine is added becomes the actual machine positioning precision. If accurate positioning precision is required at the machine, use the MDS-C1-V1/V2 series servo drive unit that allows the scale feedback to be input.
(3) Surface precision during machining :
∆ε v
This is the precision outline that affects the machine tools, etc., which are important factors in the machine operation path and interpolation functions. It also affects the surface roughness of the machining surface. The machining surface roughness is affected by elements caused by the detector resolution, the motor's electrical characteristics (torque ripple, etc.) and mechanical characteristics (cogging torque, etc.). In the NC unit feed axis motor (HC ڤ , HA ڤ N) those torque characteristics are excellent, and higher precision machining is possible than that of other motors.
Because the effects of torque ripple and cogging torque are relatively small in motors with large amounts of inertia, the motor with the larger inertia, among the two identical capacity motors, will be more advantageous for surface precision. Due to the effects of differences in characteristics of the motor itself, the surface precision during machining will differ greatly according to the motor series.
(4) Absolute position repeatability precision:
∆ε a
This is the precision outline that affects the absolute position system machine, and expresses the precision in repeatability of the position before the power was shut off and the position when the power is turned on again. With the single motor unit, the precision is 1 to 2 times the theoretic precision
∆ε
. Note that the absolute position repeatability
∆ε a is the difference between when the power was turned off last and returned on. This error is not cumulated.
A3 - 3
Appendix 3. Selection
Appendix 3-2 Selection of servomotor capacity
The following three elements are used to determine the servomotor capacity.
1. Load inertia ratio
2. Short time characteristics (acceleration/deceleration torque)
3. Continuous characteristics (continuous effective load torque)
Carry out appropriate measures, such as changing the motor series or increasing the motor capacity, if any of the above conditions is not fulfilled.
Appendix 3-2-1 Load inertia ratio
Each servomotor has an appropriate load inertia ratio (load inertia/motor inertia). The control becomes unstable when the load inertia ratio is too large, and the servo parameter adjustment becomes difficult.
It becomes difficult to improve the surface precision in the feed axis, and the positioning time cannot be shortened in the positioning axis because the settling time is longer.
If the load inertia ratio exceeds the recommended value in the servomotor specifications list, increase the motor capacity or change to a motor series with a larger inertia. Note that the recommended value for the load inertia ratio is strictly one guideline. This does not mean that controlling of the load with inertia exceeding the recommended value is impossible.
POINT
1. When selecting feed axis servomotors for NC unit machine tools, place importance on the surface precision during machining. To do this, always select a servomotor with a load inertia ratio within the recommended value.
Select the lowest value possible within that range.
2. Judge the load inertia ratio for the motor with brakes using the motor inertia of motors without brakes as a reference.
Appendix 3-2-2 Short time characteristics
In addition to the continuous operation range, the servomotor has the short time operation range that can only be used for short times such as acceleration/deceleration. This range is expressed at the maximum torque. The maximum torque differs for each motor even at the same capacity, so confirm the specifications in section "2-1 Servomotor".
The maximum torque affects the acceleration/deceleration time constant that can be driven. The linear acceleration/deceleration time constant ta can be approximated from the machine specifications using expression (a). Determine the maximum motor torque required from this expression, and select the motor capacity.
ta =
(J
L
+ J
M
)
×
N
95.5
×
(0.8
×
T
MAX
−
T
L
)
(ms) .................................................. (a)
N : Motor reach speed
J
L
: Motor shaft conversion load inertia
J
M
: Motor inertia
(r/min)
(kg.cm
2
)
(kg.cm
2
)
T
MAX
: Maximum motor torque (N.m)
T
L
: Motor shaft conversion load (friction, unbalance) torque (N.m)
A3 - 4
Appendix 3. Selection
Appendix 3-2-3 Continuous characteristics
A typical operation pattern is assumed, and the motor's continuous effective load torque (Trms) is calculated from the motor shaft conversion and load torque. If numbers <1> to <8> in the following drawing were considered a one cycle operation pattern, the continuous effective load torque is obtained from the root mean square of the torque during each operation, as shown in the expression (b).
<1> <2> <3> <4> <5> <6> <7> <8>
Motor speed
0
T 1
T 7
T 2
T 4
Motor torque
0
Time
T 3 T 6 T 8 t 1 t 2 t 3 t 4
T 5 t 5 t 6 t 7 t 8 t 0
Fig. 1 Continuous operation pattern
Trms = T1
2
·t1 + T2
2
·t2 + T3
2
·t3 + T4
2
·t4 + T5
2
·t5 + T6
2
·t6 + T7
2
·t7 + T8
2
·t8
t0
.................... (b)
Select a motor so that the continuous effective load torque Trms is 80% or less of the motor stall torque
Tst.
Trms ≤ 0.8 . Tst .................................................. (c)
The amount of acceleration torque (Ta) shown in tables 11-6 and 11-7 is the torque to accelerate the load inertia in a frictionless state. It can be calculated by the expression (d). (For linear acceleration/ deceleration)
Ta =
(J
L
+ J
M
)
×
N
95.5
×
ta
(N.m) .................................................. (d)
N : Motor reach speed
J
J
L
M
: Motor shaft conversion load inertia
: Motor inertia ta : Linear acceleration/deceleration time constant
(r/min)
(kg.cm
2
)
(kg.cm
2
)
(ms)
For an unbalance axis, select a motor so that the motor shaft conversion load torque (friction torque + unbalance torque) is 60% or less of the stall.
T
L
≤ 0.6 . Tst .................................................. (e)
A3 - 5
Appendix 3. Selection
(1) Horizontal axis load torque
When operations <1> to <8> are for a horizontal axis, calculate so that the following torques are required in each period.
Load torques of horizontal axes
Period Load torque calculation method
<1>
(Amount of acceleration torque) +
(Kinetic friction torque)
<2> (Kinetic friction torque)
<3>
(Amount of deceleration torque) +
(Kinetic friction torque)
<4> (Static friction torque)
<5>
−
(Amount of acceleration torque)
−
(Kinetic friction torque)
<6>
−
(Kinetic friction torque)
<7>
−
(Amount of deceleration torque)
−
(Kinetic friction torque)
<8>
−
(Static friction torque)
Explanation
Normally the acceleration/deceleration time constant is calculated so that this torque is 80% of the maximum torque of the motor.
–
The absolute value of the acceleration torque amount is same as the one of the deceleration torque amount. The signs for the amount of acceleration torque and amount of deceleration torque are reversed.
Calculate so that the static friction torque is always required during a stop.
The signs are reversed with period <1> when the kinetic friction does not change according to movement direction.
The signs are reversed with period <2> when the kinetic friction does not change according to movement direction.
The signs are reversed with period <3> when the kinetic friction does not change according to movement direction.
Calculate so that the static friction torque is always required during a stop.
(2) Unbalance axis load torque
When operations <1> to <8> are for an unbalance axis, calculate so that the following torques are required in each period. Note that the forward speed shall be an upward movement.
Load torques of unbalance axes
Period
<1>
(Amount of acceleration torque) + (Kinetic friction torque) + (Unbalance torque)
<2> (Kinetic friction torque) + (Unbalance torque)
<3>
Load torque calculation method
(Amount of deceleration torque) + (Kinetic friction torque) + (Unbalance torque)
<4> (Static friction torque) + (Unbalance torque)
<5>
−
(Amount of acceleration torque)
−
(Kinetic friction torque) + (Unbalance torque)
<6>
−
(Kinetic friction torque) + (Unbalance torque)
<7>
−
(Amount of deceleration torque)
−
(Kinetic friction torque) + (Unbalance torque)
<8>
−
(Static friction torque) + (Unbalance torque)
Explanation
Normally the acceleration/deceleration time constant is calculated so that this torque is 80% of the maximum torque of the motor.
–
The absolute value of the acceleration torque amount is same as the one of the deceleration torque amount.
The signs for the amount of acceleration torque and amount of deceleration torque are reversed.
The holding torque during a stop becomes fairly large.
(Upward stop)
–
The generated torque may be in the reverse of the movement direction, depending on the size of the unbalance torque.
–
The holding torque becomes smaller than the upward stop. (Downward stop)
POINT
During a stop, the static friction torque may constantly be applied. The static friction torque and unbalance torque may be applied during an unbalance axis upward stop, and the torque during a stop may become extremely large.
Therefore, caution is advised.
A3 - 6
Appendix 3. Selection
Appendix 3-3 Example of servo selection
A servomotor is selected using a machining center with the following specifications as an example.
Specification item Unit X axis Y axis Z axis
Axis type
Movement direction
Table support method
Table movement friction coefficient
Ball screw diameter
Ball screw length
Ball screw lead
Deceleration ratio
Primary side gear inertia
Secondary side gear inertia
Motor/ball screw connection section inertia
Weight of moving object installed on the machine (table, etc.)
Weight of standard-added-moving object
(workpiece, etc.)
Rapid traverse rate
Target acceleration/deceleration time constant
% mm mm mm kg.cm
2 kg.cm
2 kg.cm
2 kg kg mm/min ms
Linear Linear Linear
Horizontal Horizontal Vertical
Rolling Rolling Rolling
5 5 2
40 40 40
900 800 1000
10 10 10
1 1 2/3
− −
1.6
− −
8.1
2.0 2.0
−
500 400 400
100 100 10
30000 30000 20000
120 120 120
Rapid traverse positioning frequency times/mi n
20 20 20
Motor brake Without Without With
Appendix 3-3-1 Motor selection calculation
The selection calculation is carried out in order using the Z axis as an example. Secondary side gear
8.1kg·cm
2
Deceleration ratio = 2/3
Primary side gear
1.6kg·cm
2
(1) Obtaining the load inertia
Calculate the motor shaft conversion load inertia separately for the rotation load and linear movement load. Furthermore, calculate the rotation load inertia separately for the primary and secondary side.
•
Primary side rotation load inertia: J
R1
This is the primary side gear inertia.
J
R1
= 1.6 (kg.cm
2
)
10kg
400kg
Servomotor
Ball screw
ø40, 1000mm
Fig. 11-3 Z axis configuration
•
Secondary side rotation load inertia: J
R2
This is the sum of the ball screw inertia J
B
and secondary side gear inertia. The ball screw is generally calculated as a cylinder made of steel. Refer to section "Appendix 3-3-4 Expressions for load inertia calculation".
π
·
ρ
· L
J
R2
= J
B
+ 8.1 =
32
D
4
+ 8.1 =
= 19.6 + 8.1 = 27.7 (kg.cm
2
)
π ×
7.80
×
10
− 3 ×
100
32
×
4
4
+ 8.1
•
Total rotation load inertia: J
R
This is the sum of the primary side load inertia and secondary side load inertia. To convert the secondary side load inertia to the motor shaft (primary side), multiply by the square of the deceleration ratio.
J
R
= J
R1
+ (
2
3
)
2 ×
J
R2
= 1.6 +
4
9
×
27.7 = 1.6 + 12.3 = 13.9 (kg.cm
2
)
A3 - 7
Appendix 3. Selection
•
Linear movement load inertia: J
T
The inertia is calculated when a standard workpiece, tool, etc., is attached. The conversion to the motor shaft by the deceleration ratio is included in the movement increment per motor rotation.
Refer to section "Appendix 3-3-4 Expressions for load inertia calculation".
J
T
= W . (
∆
S
20
π
)
2
= (400 + 10) . (
10
×
2
20
π ×
3
)
2
= 4.6 (kg.cm
2
)
•
Load inertia: J
L
This is the sum of the total rotation load inertia and the linear movement inertia.
J
L
= 13.9 + 4.6 = 18.5 (kg.cm
2
)
When looking at the load inertia components, the linear movement weight tends to increase.
However, the rotation load generally accounts for most of the inertia. The load inertia does not change much even if the workpiece weight changes greatly in the table axis.
(2) Obtaining unbalance torque
The unbalance torque is obtained from the moving object weight. Here, the drive system efficiency is calculated as 1.
Refer to section "Appendix 3-3-3 Motor shaft conversion load torque".
T
U
=
(W
1
−
W
2
) · g ·
∆
S
2
×
10
3 π
·
η
=
(410 −
0)
×
9.8
×
10
×
2
2
×
10
3 π ×
1
×
3
= 4.3 (N.m)
(3) Obtaining friction torque
The friction torque is obtained from the moving object weight and friction coefficient. Here, the drive system efficiency is calculated as 1. Refer to section "Appendix 3-3-3 Motor shaft conversion load torque".
T
F
=
F ·
∆
S
2
×
10
3 π
·
η
=
µ
· W · g ·
∆
S
2
×
10
3 π
·
η
=
0.02
×
410
×
9.8
×
10
×
2
2
×
10
3 π ×
1
×
3
= 0.09 (N.m)
(4) Selecting the appropriate motor from the load inertia ratio
Because it is a machine tool, the HC Motor Series is required for the control precision, and a motor maximum speed of 3000r/min. or more is required because of the rapid traverse speed and gear ratio. Furthermore, the motor to be selected is limited to HC 3B Series because a motor with a brake is required. Note that even when the motor has brakes, use the motor inertia for a motor without brakes to judge the load inertia ratio.
The state is determined to be appropriate if the load inertia is within 3-fold of the recommended load inertia for HC53B or larger capacity as shown below.
Motor type
HC53B
HC103B
HC153B
Motor inertia
(kg.cm
2
)
Load inertia
(kg.cm
2
)
Load inertia magnification
Judgment
6.6 18.5 2.80
13.7 18.5 1.35
20.0 18.5 0.93
{
{
{
A3 - 8
Appendix 3. Selection
(5) Selecting the appropriate motor from the short time characteristics
(acceleration/deceleration time constant)
The acceleration/deceleration time constant is calculated using expression (a), and is judged whether it satisfies the target acceleration/deceleration time constant of 120ms.
HC53B : ta =
(J
L
+ J
M
)
×
N
95.5
×
(0.8
×
T
MAX
−
T
U
−
T
F
)
=
(18.5 + 8.6)
×
3000
95.5
×
(0.8
×
8.82
−
4.3
−
0.09)
= 320.5 (ms)
HC103B : ta =
(J
L
+ J
M
)
×
N
95.5
×
(0.8
×
T
MAX
−
T
U
−
T
F
)
=
(18.5 + 15.7)
×
3000
95.5
×
(0.8
×
16.7
−
4.3
−
0.09)
= 119.9 (ms)
HC153B : ta =
(J
L
+ J
M
)
×
N
95.5
×
(0.8
×
T
MAX
−
T
U
−
T
F
)
=
(18.5 + 22.0)
×
3000
95.5
×
(0.8
×
28.4
−
4.3
−
0.09)
= 69.4 (ms)
The motors that satisfy the conditions from the calculation results above are the HC103B and
HC153B as shown below.
Motor type
Maximum torque
(N.m)
Total inertia
(kg.cm
2
)
Acceleration/ deceleration time constant
[ms]
Judgment
HC53B
HC103B
8.82 27.1 320.5 ×
16.7 34.2 119.9 {
28.4 40.5 69.4 { HC153B
(6) Selecting the appropriate motor from the continuous characteristics
Generally, the state is calculated following the typical operation pattern. Because the Z axis is the vertical axis here, the motor will be judged by the stopped torque during an upward stop.
The unbalance axis torque during a stop should be 60% or less of the stall torque (rated torque for general-purpose motor). As shown in the following table, the only motor that satisfies this reference is
HC153B. From the judgment in steps (4) to (6) it is the appropriate motor with Z axis.
Motor type
HC53B
HC103B
HC153B
Stall torque
(N.m)
2.94
Torque during stop
T
U
+T
F
(kg.cm
2
)
Load rate
(%)
Judgment
4.39 149.1
Explanation
× An overload alarm occurs just by holding.
There is no allowance for an acceleration/
× deceleration operation.
The torque during stop should be 60% or less.
A3 - 9
Appendix 3. Selection
Appendix 3-3-2 Servo selection results
As a result of calculating the servo selection, the servo specifications for the Z axis of this machining center have been determined.
Servo drive unit
Servomotor
Item Type
MDS-C1-V1-20
HC153B
The in the motor type will be decided based on separate machine specifications such as motor shaft shape and absolute position system.
The following table shows the servo selections for all axes.
Item
Axis type
Movement direction
Table support method
Table movement friction coefficient
Ball screw diameter
Ball screw length
Ball screw lead
Deceleration ratio
Primary side gear inertia
Secondary side gear inertia
Motor/ball screw connection section inertia
Weight of moving object installed on the machine (table, etc.)
Weight of standard-added-moving object
(workpiece, etc.)
Rapid traverse rate
Target acceleration/deceleration time constant
Unit
% mm mm mm kg.cm
2 kg.cm
2 kg.cm
2 kg kg mm/min ms
X axis Y axis Z axis
Linear Linear Linear
Horizontal Horizontal Vertical
Rolling Rolling Rolling
5 5 2
40 40 40
900 800 1000
10 10 10
−
−
−
−
1.6
8.1
2.0 2.0
−
500 400 400
100 100 10
30000 30000 20000
120 120 120
Rapid traverse positioning frequency times/mi n kg.cm
2
20 20 20
Without Without With
19.6 17.7 13.9
Motor brake
Motor shaft conversion rotation load inertia
Motor shaft conversion linear movement load inertia
Motor shaft conversion total load inertia
Motor inertia
Motor shaft conversion load inertia magnification
Motor shaft conversion unbalance torque
Motor shaft conversion friction torque
Motor shaft conversion total load torque
Motor speed during rapid traverse
Rapid traverse acceleration/deceleration time constant
Maximum torque during motor stop
Maximum load rate during motor stop
Servo drive unit type
Servomotor type kg.cm
2 kg.cm
2 kg.cm
2
-fold ms
N.m
%
N.m
N.m
N.m r/min
15.2 12.7 4.6
34.8 30.4 18.5
13.7 13.7 22.0
2.54 2.22 0.84
0.0 0.0 4.3
0.47 0.39 0.09
0.47 0.39 4.39
3000 3000 3000
118.3 106.7 69.4
0.47 0.39 4.39
8.0 6.6 49.8
MDS-C1-V1-10 MDS-C1-V1-10 MDS-C1-V1-20
HC103 HC103 HC153B
A3 - 10
Appendix 3. Selection
Appendix 3-3-3 Motor shaft conversion load torque
The calculation method for a representative load torque is shown.
Type Mechanism
Linear movement
Rotary movement
Vertical movement
Servomotor
Z
1
1/n
Z
1
η
Z
2
Servomotor
T
LO
F c
W
Z
2
Servomotor
W
1
Load
W
2
F
0
Counterweight
T
L
2
×
F
10
3 πη
.
(
V
N
) =
2
×
10
3 π η
T
L
: Load torque
F : Force in axial direction of the machine that moves linearly
η
V
: Drive system efficiency
: Speed of object that moves linearly
N : Motor speed
∆
S : Object movement amount per motor
(N.m)
(N)
(mm/min)
(r/min) rotation (mm)
Z1, Z2 : Deceleration ratio
F in the above expression is obtained from the expression below when the table is moved as shown on the left.
F = Fc +
µ
(W . g + F
0
)
Fc : Force applied on axial direction of moving section (N)
F
0
: Tightening force on inner surface of table guide (N)
W : Total weight of moving section g : Gravitational acceleration = 9.8
µ
: coefficient
(kg)
(m/s
2
)
T
L
T
L
Z
Z
2
1
η
LO
+ T
: Load torque
F
1 n
1
η LO
+ T
F
T
LO
: Load torque on load shaft
T
F
η
: Motor shaft conversion load friction torque
: Drive system efficiency
Z
1
, Z
2 n
: Deceleration ratio
: Deceleration rate
(N.m)
(N.m)
(N.m)
When rising
T
L
= T
U
+ T
F
When lowering
T
L
= –T
U
·
η 2
+ T
F
T
L
: Load torque
T
U
: Unbalanced torque
T
F
: Friction torque on moving section
(W
1
−
W
2
) · g
T
U
πη
T
F
=
V
· (
µ
· (W
1
+ W
2
) · g ·
∆
S
2
×
10
3 πη
) =
(W
1
– W
2
) · g ·
∆
S
2
×
10
3 πη
W
1
: Load weight
W
2
: Counterweight weight
η
: Drive system efficiency g : Gravitational acceleration = 9.8
(N.m)
(N.m)
(N.m)
(kg)
(kg)
(m/s
2
)
V : Speed of object that moves linearly (mm/min)
N : Motor speed (r/min)
∆
S : Object movement amount per motor rotation (mm)
µ
: Friction coefficient
A3 - 11
Appendix 3. Selection
Appendix 3-3-4 Expressions for load inertia calculation
The calculation method for a representative load inertia is shown.
Type Mechanism
Rotary shaft is cylinder center
D1.
D2.
J
L
π
·
ρ
· L
32
J
L
: Load inertia [kg.cm
ρ
: Density of cylinder material [kg.cm
2
]
3
]
L : Length of cylinder
D
1
1
4
– D
2
4
W
) = . (D
8
1
2
– D
2
2
[cm]
: Outer diameter of cylinder [cm]
)
Reference data
Material densities
Iron
.....
×
10
–3
Aluminum
.....
×
10
–3
[kg/cm
3
]
[kg/cm
3
]
D
2
: Inner diameter of cylinder [cm]
W : Weight of cylinder [kg]
Copper
.....
×
10
–3
[kg/cm
3
]
Cylinder
Rotary shaft
When rotary shaft and cylinder shaft are deviated
R
Column a
Rotary shaft a
D b b
J
L
W
2
+ 8R
2
)
8
J
L
: Load inertia
W : Weight of cylinder
D : Outer diameter of cylinder
R : Distance between rotary axis and
[kg.cm
2
]
[kg]
[cm]
[cm]
J
L a
2
+ b
2
3
2
)
J
L
: inertia
W : Weight of cylinder a.b.R : Left diagram
[kg.cm
2
]
[kg]
[cm]
Rotary shaft
R
Object that moves linearly Servomotor
N
V
W
J
L
2
1
π
N
V
10
2
∆
S
20
π
2
J
L
: inertia [kg.cm
2
]
W : Weight of object that moves linearly [kg]
V : Speed of object that moves linearly
∆
S
[r/min]
[mm/min]
: Object movement amount per motor rotation [mm]
Suspended object
Converted load
W
N
3
J
21
Servomotor
D
Load B
J
B
J
11
N
1
J
22
N
1
J
31
Load A
J
A
N
2
J
L
D
2
2
+ J
P
J
L
: Load inertia
W : Object weight
D : Diameter of pulley
J
P
: Inertia of pulley
[kg.cm
[kg]
[cm]
2
]
[kg.cm
2
]
J
L
= J
11
+ (J
21
+ J
22
+ J
A
N
2
N
1
J
J
L
A
:
,J
B
2
+ (J
31
+ J
B
N
3
2
N
1 inertia
: Inertia of load A, B
J
11
~J
31
: Inertia
N
1
~N
3
: Each shaft’s speed
[kg.cm
[kg.cm
[kg.cm
[r/min]
2
2
2
]
]
]
A3 - 12
Appendix 3. Selection
Appendix 3-4 Selecting the power supply
When selecting the power supply capacity, select the capacity that satisfies both the "Appendix 3-4-1
Rated capacity selection" and "Appendix 3-4-2 Momentary maximum rated capacity selection".
Appendix 3-4-1 Selecting according to the continuous rated capacity
Select the power supply capacity that satisfies the following conditions for the servomotor and spindle motor to which the power is supplied.
(a) When there is only one servomotor axis
Power supply unit rated capacity
≥ ∑
(spindle motor output) + (servomotor output) ….. (1)
(b) When there are two or more servomotor axes
Power supply unit rated capacity
≥ ∑
(spindle motor output) + 0.7 × (servomotor output) ….. (2)
Rated capacity of power supply unit
150 185 220 MDS-C1-CV- 37 55 75 110
Rated capacity:
(kW)
4.2 6.0 8.0 11.5
15.5
19.0
23.0
27.0 31.0 38.0
POINT
1. When no spindle motor is used, calculate as
∑
(spindle motor output) = 0kW.
2. "Spindle motor output" refers to the short time rated output (kW) of the spindle motor.
3. If the spindle motor output in acceleration/deceleration is different from that in steady state, substitute the larger value for "spindle motor output".
4. If the spindle motor output is limited, multiply the output value by the limit rate and then substitute the multiplied value for "spindle motor output".
5. "Servomotor output" refers to the rated output (kW) of the servomotor. Note that the servomotor rated output and the drive unit capacity are not always the same.
(Example) MDS-C1-V1-35 + HC203…servomotor output = 2.0kW
A3 - 13
Appendix 3. Selection
CAUTION
1. When there are two or more servomotor axes, select the power supply unit whose capacity is the same or larger than the largest rated capacity of the loaded servomotors.
(Example) HC902(9.0kW) + HC102(1.0kW) … Select MDS-C1-CV-110.
2. If the selection capacity exceeds 38.0kW, use two or more power supply units. Select so that the capacity of each power supply unit satisfies the expressions (1) and (2).
3. Only when MDS-B-SP-370 or larger capacity spindle drive unit is connected, a large-capacity power supply unit (MDS-B-CVE-450, 550) can be used.
Refer to "Appendix 4. Explanation of Large Capacity Spindle Unit
Specifications" for details.
4. For the spindle drive unit, the drive unit capacity may become large depending on the spindle motor such as high-troupe motor. Make sure that the capacity limit of drive unit which can be connected is provided depending on the power supply.
Power supply unit
MDS-C1-CV-
Spindle drive unit
37 MDS-C1-SP □ -04 to 75
55 MDS-C1-SP □ -04 to 110
75 MDS-C1-SP □ -04 to 150
110 MDS-C1-SP □ -04 to 185
150 MDS-C1-SP □ -04 to 220
185 MDS-C1-SP □ -04 to 260
220 MDS-C1-SP □ -04 to 300
260
MDS-C1-SP □ -04 to 300
300
MDS-B-SP-370
MDS-C1-SP □ -04 to 300
370
MDS-B-SP-370 to 450
MDS-C1-SP □ -04 to 300
MDS-B-SP-370 to 550
A3 - 14
Appendix 3. Selection
Appendix 3-4-2 Selection with maximum momentary capacity
Select the capacity so that the total value of the total sum of maximum momentary output during spindle motor acceleration and the total sum of maximum momentary output during acceleration of servomotor that is accelerating and decelerating simultaneously is not more than the maximum momentary capacity of the power supply unit.
Maximum momentary capacity of power supply unit
≥
Σ
(Maximum momentary output of spindle motor)
+
Σ
(Maximum momentary output of servomotor accelerating/decelerating simultaneously)
(1) Spindle motor maximum momentary output
The maximum momentary output of the spindle motor is calculated by multiplying the acceleration/deceleration output of the spindle motor by 1.2.
Maximum momentary output of spindle motor = Spindle motor acceleration/deceleration output × 1.2
Spindle motor acceleration/deceleration output means the maximum output (kW) specified in the acceleration/deceleration output characteristics. If there are no specifications in the acceleration/deceleration output characteristics, maximum output (kW) of the short time rated output specified at a time of 10 minutes or more and 30 minutes or less.
(2) Servomotor maximum momentary output
Selection capacity of power supply unit
HC52 HC102 HC152 HC202 HC352 HC452 HC702 HC902
Maximum momentary output
(kW)
1.5 2.7 4.5 5.3 7.4 10.6 15 19.5
Motor type
Maximum momentary output
(kW)
HC53 HC103 HC153 HC203 HC353 HC453 HC703
13.7
Motor type
Maximum momentary output
(kW)
HC103R HC153R HC203R HC353R HC503R
1.5 2.3 3.0 5.3 7.6
Motor type
Maximum momentary output
(kW)
HA053N HA13N HA23N HA33N
0.15 0.3 0.6 1.1
HA-LF11K2-S8
21.7
HA-LF15K2-S8
30.6
(Note) The maximum momentary output in this table is reference data for selecting the power supply unit and is not data which guarantees the maximum output.
(3) Power supply unit maximum momentary capacity
Maximum momentary capacity of power supply unit
MDS-C1-CV-
Maximum momentary output
(kW)
37 55 75 110 150 185 220 260 300 370
14 19 21 28 41 42 53 54 55 75
POINT
1. If a spindle motor has a coil switch function, calculate with the specification of the coil that has larger acceleration/deceleration output.
2. If a servomotor doesn’t accelerate/decelerate simultaneously with others, even if its load is applied to the power supply, the motor can be excluded from the selection.
A3 - 15
Appendix 3-4-3 Selection example
Appendix 3. Selection
(Example 1) Spindle motor : 30-minute rated output 22kW × 1 axis
Servomotor : HC452 × 1 axis
HC352 × 2 axes
(The three servo axes are simultaneously accelerated/decelerated)
(1) Selection with rated capacity
Σ
(Spindle motor output) + 0.7 x (servomotor output) = 22kW + 0.7 x (4.5kW + 3.5kW x 2) = 30.05kW
→
"MDS-C1-CV-300" that has the selection capacity of 31.0kW, or larger unit is required.
(2) Selection with maximum momentary rated capacity
Σ
(Maximum momentary output of spindle motor)
+
Σ
(Maximum momentary output of servomotor accelerating/decelerating simultaneously)
= 22kW x 1.2 + (10.6kW + 7.4kW x 2) = 51.8kW
→
"MDS-C1-CV-220" that has the maximum momentary capacity of 53kW, or larger unit is required.
(3) Overall selection
Select the power supply unit "MDS-C1-CV-300" that meets the conditions (1) and (2).
(Example 2) Spindle motor : 30-minute rated output 22kW × 1 axis
Servomotor : HC453 × 2 axes
HC353 × 1 axis
(The three servo axes are simultaneously accelerated/decelerated)
(1) Selection with rated capacity
Σ
(Spindle motor output) + 0.7 x (servomotor output) = 22kW + 0.7 x (4.5kW x 2 + 3.5kW) = 30.75kW
→
"MDS-C1-CV-300" that has the selection capacity of 31.0kW, or larger unit is required.
(2) Selection with maximum momentary rated capacity
Σ
(Maximum momentary output of spindle motor)
+
Σ
(Maximum momentary output of servomotor accelerating/decelerating simultaneously)
= 22kW × 1.2 + (13.7kW × 2 + 10.6kW) = 64.4kW
→
"MDS-C1-CV-370" that has the maximum momentary capacity of 75kW, or larger unit is required.
(3) Overall selection
Select the power supply unit "MDS-C1-CV-370" that meets the conditions (1) and (2).
A3 - 16
Download
Public link updated
The public link to your chat has been updated. You may view and manage your chat links after registration here.
Document public link
Advertisement
Key features
Precise AC servo and spindle drive control
Enhanced machine tool integration
Comprehensive safety features to prevent electric shocks and injuries
User-friendly interface for simplified operation
Robust construction for reliable performance in industrial environments
Advanced diagnostics for proactive maintenance and troubleshooting
Frequently asked questions
No, operating the unit with the front cover removed is strictly prohibited due to exposed high voltage terminals and charged sections that pose an electric shock hazard.
Wait at least 15 minutes after turning the power OFF to allow the unit to discharge before starting any maintenance or inspection work.
No, applying a voltage other than the specified value can lead to ruptures or damage to the unit.
Use only the servomotor's hanging bolts for transportation and avoid holding the cables, axis, or detector during the process.