kisssys 03/2014 tutorial...gpk 07/11/2014 . 10.11.2014 2 / 18 foreword this tutorial is meant to be...
TRANSCRIPT
KISSsoft AG
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Switzerland
Tel: +41 55 254 20 50
Fax: +41 55 254 20 51
www.KISSsoft.AG
KISSsys 03/2014 – Tutorial
GPK
07/11/2014
10.11.2014 2 / 18
Foreword
This tutorial is meant to be used as a starting instruction for correct working procedure through gearbox design with GPK pre-made models. In this tutorial we will use a ThreeStageHelicalGearbox with Bearings as a basis. Similar procedure is to be used when working with any other GPK model. Using the GPK models doesn’t require any programming skills or model building. Every component and functionality needed for working with the models is already programmed in the models. In case the user wants to add something (calculations, new components...) to meet own requirements, it can be added. In this case contact KISSsoft AG for more help.
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Contents
1. Sizing task ................................................................................................................................................ 4 1.1 Input data ........................................................................................................................................ 4 1.2 Purpose of this tutorial .................................................................................................................... 4
2. Preparations ............................................................................................................................................. 4 3. Sizing a gearbox ...................................................................................................................................... 4
3.1 General notes ................................................................................................................................. 4 3.2 Settings ........................................................................................................................................... 4 3.3 PreSizing ........................................................................................................................................ 7
3.3.1 Iteration for sizing ....................................................................................................................... 8 3.3.2 Final sizing ............................................................................................................................... 10 3.3.3 Gears ........................................................................................................................................ 10 3.3.4 Shafts ....................................................................................................................................... 13 3.3.5 Final notes of sizing .................................................................................................................. 15
4. Final Calculations ................................................................................................................................... 16 4.1 UserInterface ................................................................................................................................ 16 4.2 Strength calculation ...................................................................................................................... 16 4.3 Torque capacity ............................................................................................................................ 17 4.4 Reports ......................................................................................................................................... 17
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1. Sizing task
1.1 Input data
Design a three-stage helical gearbox with input speed of 3000rpm clockwise and a required output moment of 20000Nm. Total ratio 100 ± 3 %. The Gearbox will be used in upright position so that input and outputs are on the same side of the gearbox and vertically on the same plane. Space between input and output is to be ~500mm.
Table 1.1 Input data for gearbox sizing
Input speed 3000 rpm
Required minimum output torque 20000 Nm
Ratio 100 ± 3 %
Required lifetime 10000 h
Oil General type industrial oil
Operating temperature 70 °C
Required safeties Shafts 1.25, Gears SH = 1, SF = 1.4
1.2 Purpose of this tutorial
After completing this tutorial the user is able to use the GPK – library models on his/her own. These ready made models can be used as “template” models to start the creation of own gearbox layouts and calculations. This tutorial will show the correct working procedure through the design procedure. Not in every case all described steps are necessary and in other cases some more iterations or tuning is needed to get best possible solutions.
2. Preparations
According to given data GPK model “ThreeStageHelicalGearBox” will be selected as a starting point. If you
don’t have that model, please go to http://www.kisssoft.ch/english/downloads/gpkdownload.php and
download the correct file from there (“ThreeStageHelicalGearBox.ks”).
Create a project folder and place that GPK library file into the folder. Open up KISSsys and select working
directory to be that newly created project folder. Go to Menu – File – Open and select the file
“ThreeStageHelicalGearBox.ks”. The GPK file is opened and ready for use.
3. Sizing a gearbox
3.1 General notes
All the operations described in here are made using the tables. The tables are created to ease the operation
of the models. It is also possible to use the tree structure of the model to run the same functionalities and
procedures. In general all the infomation, variables and functions are saved in the properties of the different
elements. By use of the right-mouse click on the tree it is possible to view the menu for every element and
have a look at the list of possible variables and functions and also to run the functions.
3.2 Settings
Start with giving correct global setting values for “Settings” table.
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Figure 3.1 Settings via table
1. Select lubricant and lubrication method, as well as the lubrication temperature. Note! Ambient temperature has an effect only when using plastic gearing. 2. Define the mounting position and required lifetime for the gearbox 3. Define the efficiency for gears manually or let the program calculate the efficiency while running the kinematic calculation. Adjust KA to 1.25. 4. Select calculation methods for components. Use classical method (according to ISO 281) for bearings to consider also the lubrication. 5. Define materials for components. Pinion type gears will be gear1, gear3 and gear5 on shafts 1, 2 and 3, so materials for those shall be equal. 6. Double-click “Update model” to accept all changes. Use functions “Model ID” to give correct information to model and “Price settings” to define pinion shafts and price estimations. (Note! Approximate price for gearbox is calculated according to given base costs/kg. User needs to define these prices according to own knowledge)
Figure 3.2 Model information dialog
1.
2.
3.
4.
5.
5.
6. 7. 8.
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Figure 3.3 Price setting dialogs for price calculations settings
7. Use the function “Setup I/O” to define speed for the Shaft1 (Boundary1) and torque for the Shaft4
(Boundary2). Torque can always be defined as input or output, meaning the gearbox can be easily
calculated for both directions.
Figure 3.4 Power definition dialog
8. At this point it is also possible to change the bearings to support only. This can be done using the
function “Model Setup”.
Figure 3.5 Bearing settings
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3.3 PreSizing
Because no initial information about the gearbox size is given, the sizing of the gearbox can be started by
giving a total required ratio for the gearbox. Type in the value of 100 for total ratio and give it a deviation of
3%. Then click on “Divide ratio” to divide this total ratio over the three reductions. The ratios reached are
good starting values and can afterwards be changed if needed. When the helix angle range is to be
modified, it can be done using the function “Gear sizing param.” Range can be selected here freely, e.g.
Figure 3.6 Definition for the helix angle
After the settings have been made it is possible to try the gear sizing function. Select initial sizing strategy “i
fixed” from the drop-down list and execute sizing functions: “Sizing gear pair 1”, “Sizing gear pair 2” and
“Sizing gear pair 3” in this order. With this sizing method only the ratio is fixed for gears and all other values
(helix angle, width, centre distance...) are selected in order to have a good overall solution. After the pre-
sizing, gear geometries are proposed and an updated layout can be seen in 3DView. Then the same can be
done for the bearings and the shafts. For “Shaft and bearing sizing” choose “Use types defined below” and
select desired bearings from the list “Types of bearing”. Select how shaft ends are positioned from the list of
“Coupling side” and “Gear side in the first shaft”. Initially we will use the “Deep groove ball bearing (single
row)” because they are the cheapest and most common type of bearings. Also type in the required shaft
safeties (fatigue = 1.25 and Static = 1.25). Then double-click on function “Shaft and bearing sizing” to make
initial sizing for bearings and shafts.
Figure 3.7 Sizing of gears and sizing of shafts and bearings
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If a Message for geometrical errors appears, we need to do some adjustments for the gearbox.
Figure 3.8 Information of geometrical error during first pre-sizing
Figure 3.9 Geometrical error and possible collision in 3DView
3.3.1 Iteration for sizing
The first and last gear pairs are colliding. This can be prevented by increasing the centre distance of the
second gear pair. At the same time we can also adjust the centre distances of the other stages to achieve
reasonable rounded numbers. This can be done by typing in the new values for Pair1 = 200, Pair2 = 260
and Pair3 = 300 and by selecting sizing strategy to be “i,a fixed” and executing gear pair sizing again.
Finally the same should be done for the “shaft and bearing sizing” Function to get a new layout.
Before sizing of shafts and bearings you can also turn the gearbox in the correct working position by
changing axis angles to consider all forces correctly for every bearing. There may be several “internal”
layouts for the gearbox to achieve the required output shaft position.
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Figure 3.10 Gearbox positioning in space and new pre-sizing
After the pre-sizing the 3DView can be also adjusted. By clicking on the icon in the top menu bar and
changing the settings in the dialog. To turn the housing invisible in the 3DView right-click on “Housing” in
the structure tree, choose SetColor and set transparency to 1.
Figure 3.11 Color Settings for the housing
Figure 3.12 Gearbox layout after pre-sizing
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3.3.2 Final sizing
After pre-sizing, the final sizing for gears, shafts and bearings must be done. Also the correct geometry for
shafts should be entered, because after pre sizing shaft geometry is only estimated.
Figure 3.13 Definition of shaft1 after pre-sizing
While final sizing please remember to use the function “Update model” in the right hand side upper corner
of the tab “UserInterface” to update all the changes made.
3.3.3 Gears
Make the final sizing for all gears individually using the according gear pair mask found in the structure tree
on the left hand side. You may adjust e.g. the reference profile, modifications, tooth form, the profile shift
coefficient, facewidth or any other variable that may become necessary. In this example we will change
gear widths to be reasonable values.
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Figure 3.14 Structure tree with gear pair mask
The type of profile modification is set “for high load capacity” under “Rating - Details” and “Optimal tip relief
(micropitting, scuffing)” will be checked to get better load distribution for the gears. This will be done for
every gear.
Figure 3.15 GearPair details of strength
For specific modifications, the modifications tab can be activated from the Calculation menu on top of the screen
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Figure 3.16 GearPair sizing modifications
After setting values for all the gears. The GearPairResults should like this:
Figure 3.17 Geometry after final sizing of all the gears
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3.3.4 Shafts
Define correct shaft data for every shaft. Start by deleting initial shaft geometry and then input new
geometry via shaft graphical input window. Bearings and force elements can be also repositioned and
correct bearings can be selected to support the shafts. If you right-click a bearing you can also choose
sizing which opens a dialog with a choice of pre-specified bearings and the corresponding service life.
Figure 3.18 Detailed geometry for shaft1 after input in graphical shaft editor
Define new shaft geometry and insert notch factors. If bearing lifetime will get too high or too low with
selected shaft diameters you may have to execute some iterations before you find fitting shaft
measurements. It is also possible to change bearing type into a more loads carrying type of bearing if shaft
diameter gets too big.
You can also define a new cross section to calculate. This can be done e.g. automatically using the “sizing”
function from the shaft tree. First remove the current cross sections then create cross sections where the
shaft strength is to be calculated.
Proceed the same way with the other shafts. For shafts 2, 3 and 4 it is also possible to add a notch effect of
key way or pressure fit, depending on how “loose” the gear is fixed on the shaft. These notch effects can be
added by right-clicking on the shaft and choosing the appropriate option from the add-menu while in
graphical shaft editor.
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Figure 3.1918 Final geometry for shaft2 with key way notch effect
Figure 3.20 Shaft3 after defining final geometry
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Figure 3.21 Shaft4 after defining final geometry
The bearings are selected using graphical shaft interfaces. The list of selected bearings is shown as
follows:
Figure 3.22 Selected bearings for the gearbox
3.3.5 Final notes of sizing
In this example “Deep groove ball bearings (single row)” and “Cylindrical roller bearings (single row)” are
used. This selection is made because when loads get quite big due to high torque, bearing size will have to
increase as well. This effect is amplified if deep groove ball bearings are used on each shaft. That may lead
to an over-sizing of shafts. In this case bearing types are changed to “Cylindrical roller bearings” three
shafts. This type of bearing has a higher load carrying capacity and therefore shaft size can be kept low and
safety factors for shafts are in reasonable level. Deep groove ball bearings are low-cost bearings so it is
advised to keep the detailed analysis of total price in mind when changing the bearing type.
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4. Final Calculations
4.1 UserInterface
Use function “Update Model” and “Calculate Kinematics” in “UserInterface”-tab before final strength calculation to make sure that all changes in components are updated before calculation.
Figure 4.1 Use "Update model" and "Calculate Kinematics" before final calculations to actualize every
component after changes
4.2 Strength calculation
After every component has been selected and adjusted do final strength calculation. That can be done via
“UserInterface” with function “Calculate Strength”. After calculation is performed you should see a message
that strength has been calculated.
Figure 4.2 Message after strength calculation, indicating the calculation was a "success"
1. 2. 3.
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4.3 Torque capacity
Are you also interested to know what the torque capacity of your gearbox with defined components is? That
can be easily checked with function “Calculate Torque Capacity” in “UserInterface”. The function will iterate
input torque until some of the required criteria will fail. The result will be given as maximum torque for the
gearbox.
Figure 4.3 Information about the requirements to be fulfilled
Figure 4.4 Limiting calculation and max. torque is displayed after torque capacity calculation
Limiting calculation is the second gearpair. The maximum applied torque output for that gearpair is
20226.577Nm with given efficiencies. Initially 20000Nm as output torque requirement was given for the
gearbox. This means after the gearbox dimensioning the required lifetime and torque can be achieved.
4.4 Reports
After all calculations are done the last step is to create the necessary documentation for the gearbox. That
can be done with the function “Reports” from “UserInterface”
Figure 4.5 Report selection dialog
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Select the desired report from the list and select “Ok”. All available reports are saved automatically to the
project folder and can be accessed later. The “General report” is a short summary of most important results
e.g. to be given for customer. “KISSsoft reports” are a full documentation of all results in one file according
to KISSsoft protocols. “Bearing forces” will create a file consisting of global coordinates of every bearing
with bearing force components, e.g. to be used in housing FEM analysis.