Kisssoft Tut 009 E Gearsizing

8/13/2019 Kisssoft Tut 009 E Gearsizing

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1 / 14 15. February 2011 Release 03/2011

KISSsoft AG - +41 55 254 20 50Uetzikon 4 - +41 55 254 20 518634 Hombrechtikon - info@KISSsoft. AGSwitzerland - www. KISSsoft. AG

KISSsoft Tutorial: Fine Sizing of Cylindrical Gears

1 Task

1.1 Task

A helical gear pair is to be designed such that it has a service life of 5,000 h when transmitting

5 kW at 400 rpm (application factor = 1.25) The ratio shall be 1:4 (reducing speed) and

18CrNiMo7-6 is to be used as the gear material. The helical gear pair is to be optimized to

achieve the best possible noise/contact ratio. Strength calculation is to be performed as

specified in ISO 6336 Method B.

1.2 Starting gear pair calculation (helical gear pair)

Once you have installed and activated KISSsoft either as a test or licensed version, follow

these steps to call the KISSsoft system. Usually you start the program by clicking

"Start!Program Files!KISSsoft 03-2011!KISSsoft". This opens the following KISSsoft user

interface:

Figure 1.1 Starting KISSsoft, initial window

In the Modules tree window, select the "Modules" tab to call the "cylindrical gear pairs"

calculation:

Figure 1.2 Calling cylindrical gear calculation

To open the example used in this tutorial, click "File/Open" and select "Tutorial-009-Step1" (to"Tutorial-009-Step5") or click the tab in the "Example" window. Each section in this tutorial

describes which file you need to open (as shown below).

KISS

softTutorial009:Fine

Sizing

ofCylindricalGears
mailto:info@KISSsoft.


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Figure 1.3 Options for opening the example files used in this tutorial at different stages of progress

2 Rough sizing of a gear pair

2.1 Calling the Rough sizing function

Use the Rough sizing function to create a sensible initial layout for a cylindrical gear stage. To

do this, input the required key data after you call the Rough sizing function by clicking

"Calculation"!"Rough sizing"in the Rough sizing screen.

To access this stage of the calculation directly, open the "Tutorial-009-Step1" file

Figure 2.1 Calling Rough sizing


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Here it is essential that you define the required ratio (including any permitted variation in %

(here 5%)) and input the transmissible power and the material. You can also predefine the

required helix angle or center distance. The helix angle depends on the type of bearing used

with the shaft. The helix angle may be larger or smaller, depending on how much axial force

the bearings can support. The helix angle can be optimized later on during Fine Sizing. Here, in

the Rough sizing function, you should only input an approximate value for the helix angle, or

"zero" for a spur gear. You can input additional information in the "Rough sizing"input window

in the "Geometry" group. For example, the number of teeth on the pinion, the geometryproportions and the center distance.

Figure 2.2 Input window Rough sizing group: "Geometry" Conditions Number of teeth, gear 1

Click the "Details" button in the "Rough sizing" input window in the "Strength" group to

predefine the safety factors that are to be achieved.

Figure 2.3 Input window Rough sizing group: "Strength" Conditions safeties

Click the Calculate-button and the KISSsoft system will calculate different solutions for a gear

pair that fulfills the specified conditions. These solutions are then displayed in the list shown

below.


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Right-hand mouse click

in the results list to select

the criteria you want to

use, such as center

distance a, width b etc.

Figure 2.4 Cylindrical gear-Rough sizing, results

To select one of these solutions, (here with a center distance of 107 mm), click on it in the list

and then click the "Accept"button. Then click "Close"to close the list.


Figure 2.5 Normal module, number of teeth, width, profile shift and center distance as proposed by the

KISSsoft system

2.2 Modifications

You can now modify the proposed values, for example, for the gear width you can input a

pinion width of 28 mm, or a gear width of 27 mm (directly in the appropriate fields).You can also change the reference profile in the drop-down list in the "Reference profile"tab.

Figure 2.6 "Reference profile" tab, information about the reference profile


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To modify the profile shift of gear 1 (gear 2 will then be calculated to match), click the Sizing

button to open the "Sizing of profile shift coefficient"dialog window in the lower figure.

This window contains proposed values for various different profile shift coefficients (see Figure

2.7):

Figure 2.7 Dialog window; size profile shift coefficients

If you use different criteria, the KISSsoft system proposes suitable profile shift coefficients. In

this example you want to balance specific sliding. Select the proposal you require from the

right-hand side by clicking the "Selection button". Then click "OK"to accept it.

The profile shift coefficient x now appears in the input window in the "Basic data" tab in the

"Geometry" group. Then either click in the tool bar or press "F5" to calculate the complete

geometry, the root and flank safety factors, safety against scuffing and the resulting contact

ratio (see Figure 2.8below). The results should now look like this (however, minor variations

are possible, for example in the calculated profile shift coefficient):

!Various methods for sizing theprofile shift coefficient

!Sensible suggestions for the profile

shift coefficient

!Maximum and minimum (pointedtooth without undercut)


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Figure 2.8 Modified profile shift coefficient, run the calculation, results overview

3 Fine Sizing

3.1 Starting the Fine Sizing functionNow that you have used the rough sizing function to define a gear pair that can transmit the

required power, you can optimize this gear's noise emission and strength characteristics. As

with rough sizing, go to "Calculation"but then select "Fine Sizing"to call a different screen,

"Fine Sizing", in which you run the fine sizing function.

Figure 3.1 Starting "Fine Sizing"

Here you can define ranges (and intervals) for the following parameters. The KISSsoft system

will then search these ranges for a suitable gear pair solution.


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Figure 3.2 Input window - Fine Sizing, specifying the parameter areas

(1) Set to 300

(2) Define the required ratio and permissible error

(3) Click the Sizing button . KISSsoft will then propose sensible ranges for these

parameters: "Normal module", "Helix angle", "Center distance" and "Profile shift

coefficient"

(4) Specify whether the center distance is to be fixed or variable

- Range for normal module

- Range for helix angle

- Range for center distance (here set the "Variable center distance" flag)

(A note about the sizing of this value has already been displayed as the result of the rough

sizing process.)

You can also predefine these parameters:

- Maximum tip diameter

- Minimum active root diameter

- Fix the number of teeth for one of the two gears (set the flag for the suitable gear if 0:

number of teeth variable)- Fix the profile shift coefficient for one of the two gears (set the flag for the suitable gear)

For this example, make the settings shown in Figure 3.2. Click "Calculate"(button at bottom

of dialog) to call the sizing function. The algorithm this triggers then finds all possible gear

combinations that match the values you have input.

Once the calculation process has finished, you see a list of all the solutions the system found

(see Figure 3.3). In this example, the aim is to find a gear pair with low noise emissions. You

can now sort the results by the required criterion (e.g. c) to find the best solution. Double-click

on the required variant or click "Accept" to transfer and calculate the result. If the result is not

the optimum solution, you can always select a different variant until you find the best possible

result, and you can close the window.In this case, solution 31 has been selected.

1

2

3

4


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Figure 3.3 List of all solutions found in the Parameter group

Then press "Report"to evaluate the most important properties of this solution and output them

in a report.

Analysis of the results (Assessment of important characteristics)

Comment:No. = Number of the variantdiff_i = Deviation from the nominal ratio in %kg = Weight in kgSlide = Specific sliding (maximum value)v.Slide = Sliding velocity (m/s, maximum value)AC/AE = Begin working depth AC / working depth AE

(Friction)del_cg = Variant on the stiffness during rolling (N/mm/mym)

(Calculation WITHOUT taking into account the exact tooth-shape)1-eta = Losses in % (1.0-total efficiency)Safety = Safety (Tooth root and flank, 0 = high, 1 = medium, 2 = low)

(SF-min: 0.60/ 1.20/ 1.40 SH-min: 0.60/ 0.90/ 1.00)Summary = Overall assessment (weighted)

(50.0%:del_cg 20.0%:diff_i 100.0%:kg 35.0%:Slide 0.0%:v.Slide0.0%:AC/AE 10.0%:1-eta 100.0%:Safety)

(For this table it can be said in general: the smaller the value the better!)

No. diff_i kg Slide v.Slide AC/AE del_cg 1-eta Safety Summary1 0.000 5.392 1.003 0.189 0.519 1.778 1.023 1.145 0.5422 0.000 5.379 0.835 0.191 0.472 1.813 1.013 1.248 0.5833 0.000 5.367 0.689 0.206 0.423 1.874 1.036 1.270 0.591

72 1.250 5.438 0.820 0.253 0.412 0.200 1.284 0.756 0.38573 -1.190 5.432 2.364 0.274 0.477 0.151 1.542 0.660 0.35474 -1.190 5.416 1.742 0.294 0.430 0.164 1.558 0.710 0.371

Analysis of the results(with the variant index in decreasing order)

Best variant for accurate ratio:1 2 3 17 18 19 34 35 36 43 ...Best solutions for weight 13 31 11 12 30 16 10 3 29 19 ...Best variants relative to friction (AC/AE): 61 67 48 45 58 64 39 22 9 42 ...Best solution for stiffness: 12 15 21 17 18 22 13 14 16 20 ...Best variant for strength: 73 52 74 53 32 71 65 46 68 72 ...Best overall variants (summary) : 3 52 74 53 32 65 71 43 67 72 ...

Figure 3.4 Evaluating the solutions

Important note: the procedure has only been described very briefly here. In real life it is

essential that you investigate the "Results analysis"list very carefully. It is very possible that

the second or third best solution, with regard to noise emissions, should be preferred for other


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reasons. It is also helpful to display the variants as a graphic. To do this, click the "Graphics"

tab:

Figure 3.5 Graphical display of all solutions

You can use this graphic to find the best possible solution. Then click "Results"to select and

accept it.

3.2

Results of the Fine Sizing function

The total contact ratio is close to 3.1, i.e. the variation in contact stiffness is very small (see

Figure 3.6) and the gear will generate only minimum vibration.


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Figure 3.6: Results (profile shift, helix angle, number of teeth) from Fine Sizing

The resulting tooth form then appears under "2D geometry" in a graphics window. You can

now click (red marking in Figure 3.6) or double-click the left-hand mouse button in the

selected area (see blue area in Figure 3.6) to release and magnify the tooth form:

Figure 3.7 Resulting tooth form (base circle and line of action are shown in red)

To display the stiffness curve above the meshing, click "Graphics" "Evaluation""Theoretical contact stiffness":


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Figure 3.8 Progression of theoretical meshing stiffness

3.3 Sizing a deep tooth form

In the next step you can further improve the selected solution. To do this, increase the

transverse contact ratio "a to 2. If you want to calculate a tip relief later on, you will need a

higher contact ratio because this will be reduced by the tip relief). You should now also

increase the resulting contact ratio by sizing a deep tooth form (define the target size in the

"Module specific setting", "Sizings"tab).

Figure 3.9 Module-specific settings

To size a deep tooth form, call the Fine Sizing function again and then set the flag in the

"Sizing of deep tooth form"checkbox under "Conditions II". Then click the Calculate button

to calculate new values.

Figure 3.10 Settings in Fine Sizing, selecting "Sizing of deep tooth form"


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Now the best solution in terms of noise emission is solution number 23. You can now select

this variant by clicking "Accept" to transfer the toothing data for this variant. Now you have

sized a deep tooth form, the reference profiles will have been changed.

The gear data now appears again in the main screen (changed number of teeth, helix angle,

profile shift) and the new results are calculated immediately when they are accepted:


Figure 3.11 New gear data and results, in particular contact ratio

The resulting tooth form then appears under "2D geometry" in a graphics window. You can now

click (red marking in Figure 3.6) or double-click the left-hand mouse button in the selected

area (see blue area in Figure 3.6) to release and magnify the tooth form:

Figure 3.12 Resulting deep tooth form


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Figure 3.13 Viewing the reference profile for a deep tooth form in the "Reference profile" tab

The resulting contact ratio is now very close to three, which results in very even contact

stiffness:

Figure 3.14 Theoretical contact stiffness

3.4 Further details about strength analysis

For a final gear strength analysis, you must input values for lubrication and for the face load

factor:


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Figure 3.15 Inputting lubrication data and calling the input window for the face load factor

You can select the lubrication type as well as the lubricant itself directly in the drop-down list

(shown here on the left and right). You can also use the database tool to extend the lists of

lubricants.

Click the plus button (shown below on the right-hand side, see Figure 3.15) to specify the

lubricant temperature.

Input the operating and ambient or housing temperature in the "Operating backlash"tab (see

the markings in the next figure).

Figure 3.16 Operating backlash

The face load factor can be

determined using Method A, B or C.

You will find more information about

this in separate instructions in

"kisssoft-anl-002-D-Eingabe-des-

Breitenlastfaktors-KH.doc" which you

can request from KISSsoft Support.

However, you do not usually need to

make any changes here.

Figure 3.17 Inputting more parameters, especially entries for defining the face load factor

Important note:

If the strength analysis or service life calculation is relevant for evaluating the variant calculated

by the fine sizing function, you must input the values listed above before you perform fine

sizing.

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Kisssoft Tut 009 E Gearsizing