Method and apparatus for measuring pitch, rake and squareness of a boat propeller

The present invention provides a method of determining certain propeller parameters for a boat propeller that has a hub, a central axis and a plurality of propeller blades attached to the hub. The method includes providing a laser displacement sensor in proximity to the propeller. The laser displacement sensor has a laser head that generates a laser beam. The laser displacement sensor is used to measure the distance from the laser head to the propeller. The laser head is moved and the laser again measures the distance from the laser head to the propeller after the laser head is moved in relation to the propeller. The movement can be along either or both of the two axes including a first axis that is a linear axis and a second axis that is curved. The method includes computing a selected parameter or parameters by using the measurements that are obtained, the parameters being selected from a group that includes pitch, rake and squareness.

Not applicable

REFERENCE TO A “MICROFICHE APPENDIX”

Not applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus of measuring selected parameters relating to a boat propeller. More particularly, the present invention relates to an apparatus and method that measures the pitch, rake and squareness of a boat propeller.

2. General Background of the Invention

The present invention provides a method and apparatus that reads the pitch, rake and squareness of a boat propeller and lays out a pattern for boat propellers. It can be a self-contained unit as well as or mount to a propeller straightening machine. Servo motors can be used to propel it. It actually reads the pitch, rake and blade squareness with a laser. The apparatus can be controlled using a computer.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a method of determining propeller parameters for a boat propeller that has a hub, a central axis and a plurality of propeller blades attached to the hub.

The method includes providing a laser displacement sensor in close proximity to the propeller. The laser displacement sensor is used to measure the distance from the laser head to the propeller. The laser head is moved and the laser displacement sensor again measures the distance from the laser head to the propeller after the laser head is moved in relation to the propeller along either or both of the two axes including a first axis that is a linear axis and a second axis that is curved.

The method includes computing a selected parameter or parameters by using the measurements that are obtained, the parameters being selected from a group that includes pitch, rake and squareness.

The method of the present invention provides a method and apparatus to measure the pitch, rake and squareness of a boat propeller. The method of the present invention uses a laser to measure the distance from a laser head to the propeller. The laser head is moved on two axes, which can be computer controlled, driven by servo motors, for example. One axis moves from the center of the propeller outwardly. This axis will move the laser head out to a controlled circumference setting. The other axis will rotate the laser head 360° around the propeller central axis.

The method of the present invention provides a laser scan that is controlled by a computer. Controlling software can be prepared using Microsoft® Visual Basic software. A display can be provided to display company information such as company name, address and logo.

The data will include the measured pitch of the propeller. The pitch is defined as the distance the propeller will move in one complete revolution and is displayed in inches.

The data also will include the measured rake of the propeller. The rake is defined as the amount the blade is bent in relation to the hub and is displayed in degrees.

The data will also include the squareness of the propeller. The squareness is defined, as the distance the blades are separated and is displayed in degrees. A screen will also display a graph representing the measured blade parameters, including all of the measurements listed above.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1-4show the preferred embodiment of the apparatus of the present invention designated generally by the numeral10. Propeller measuring system10is shown inFIGS. 1-4measuring a propeller11that has a hub12and a plurality of blades13,14,15,16.

In most cases, a propeller11being measured is a damaged propeller. Assume that a 24″ diameter propeller with 24 pitch has one blade that is damaged. If the blade is damaged, its pitch could vary. The blade may be damaged so that it gives pitch readings of 21, 22 and 23 at different locations on the blade and at a given radii (e.g. 50% radius or 6″ from the hub). After the blade is measured, this damage is quantified, making repair easier. During the repair process, a user can check the propeller parameters from time to time until the propeller has been restored to its as manufactured dimensions, pitch, rake, squareness. Further, the damaged blade may not be squared with the other blades. On a four blade propeller, squareness is correct if the blades are exactly ninety degrees (90°) apart. The damaged blade may be eighty eight degrees (88°) from the blade closest to it.

In order to measure a propeller11, the hub12is mounted upon support17. The support17provides a conical outer surface18that is receptive of the hub12of the propeller. Support17also provides a conical socket19that is receptive of shaft21of measuring apparatus20. The vertical shaft21provides a conical outer surface22that mates with a correspondingly shaped conical socket19of support17or removal therefrom.

The assembly of the apparatus20to support17is indicated schematically by arrow23inFIG. 1. Handles24can be provided for lifting and manipulating apparatus20during such placement upon support17.

The apparatus20carries a laser displacement sensor25. Sensor25is a commercially available device, sold by Micro-Epsilon (www.micro-epsilon.com). The sensor25can be a 1750-500CCD laser displacement sensor, 500 mm range (for example model no. OPTONCDT1700). Such a sensor operates according to the triangulation principle. A laser diode projects a visible spot of light through an optical receiving system onto a positive sensitive element (CCD array). If the target changes its distance to the sensor, this leads to a change of the imaging spot on the CCD array. The position of the spot incident on the CCD array is evaluated. The laser takes about 40,000 samples in a 360 degree sweep of the propeller11. This laser sensor25is used to measure the distance between the laser25and the propeller11blade13,14,15, or16. The laser25puts out an analog signal that is proportional to that distance. The analog signal is then applied to a driver (e.g. National Instruments driver used with Microsoft® Visual Basic software such as model number N.I.NIDAQVER). This driver enables data retrieved from laser sensor25using Microsoft® Visual Basic software. The data is entered into a computer via the drivers and Microsoft® Visual Basic software.

Apparatus20has a slide26that carries bracket28. Slide26can be obtained from IAI actuator (www.intelligentactuator.com), for example their part number DS-SS6-1-30-3-400-C1-N. Slide26is supplied with Microsoft® Visual Basic drivers that enable control of motor27and data retrieval from the motor27. The bracket28supports laser displacement sensor25. Motor drive27can be used to move the bracket28and its laser displacement sensor25to a selected position upon slide26as indicated schematically by arrows43inFIG. 3.

Motor drive27engages a threaded shaft29. The shaft29engages internally threaded sleeve44that mounts to slide bracket28as shown inFIG. 2. A bearing45supports an end of shaft29opposite motor drive27. Arrow30inFIG. 2illustrates the ability of bracket27to be moved to a selected position upon slide26. Thus, rotation of motor drive27rotates shaft29, moving bracket28and sensor25.

A second motor drive31is provided for rotating the slide26and thus slide bracket28and laser displacement sensor25through a circle or arc (e.g. 360 degrees) relative to propeller11. Motor drive31is coupled to a right angle gear box32providing drive shaft33, bevel gears34,35and vertical shaft36. A bearing37(e.g. ball bearings) can be used to support rotary movement of arm26relative to propeller11. The bearing37can be contained within a protective housing. The motor drives27,31are commercially available from Animatics Corporation, 3050 Tasman Drive, Santa Clara, Calif. 95054 (www.smartmotor.com) The motor31can for example be Animatics Smartmotor® model SM2337DT. This product is supplied with Microsoft® Visual Basic drivers that enable operation and control of motor31and data retrieval from the motor by use of Microsoft® Visual Basic software. Motor31rotates the laser sensor25three hundred sixty degrees (360°).

As part of the method of the present invention, the slide26is rotated 360 degrees after the laser displacement sensor25is affixed to a selected position along the slide26. In this fashion, multiple concentric circles (38,39inFIG. 3;89-92inFIG. 11) can be tracked by the beam40as illustrated inFIGS. 3 and 11. A first inner circle38inFIG. 3is illustrated as well as a second outer circle39. It should be understood however that any number of circles38,39can be generated with the laser displacement sensor25when it is positioned at different distances along slide26as selected by a user. InFIG. 11, a grid is defined by curved lines89-92and radial lines93-95. The laser sensor25measures each blade13,14,15,16of propeller11in such a grid fashion.

A laser beam40is emitted by laser displacement sensor25that strikes its target41on the propeller blades13,14,15,16. The laser displacement sensor25also provides optical paths42that use triangulation to determine the distance between the laser displacement sensor25and the target41.

The present invention provides a method and apparatus for measuring selected parameters relating to a boat propeller using a computer. The apparatus utilizes laser displacement sensor25to measure the distance from a laser head to the propeller11. The laser sensor25measures the distance between the laser head and propeller11at intervals while being moved along two axes. The first axis is a linear axis (see arrow30,FIG. 2). The second axis is a curved axis (see arrows38,39inFIG. 3). The linear axis moves the laser from the center of the propeller outward while the curved axis rotates the laser 360 degrees around the propeller11.

The pitch is defined as the distance a propeller will move in one complete revolution and is displayed in inches. The method and apparatus of the present invention uses a computer to calculate the pitch by recording the distance between two points, done by counting pulses from the encoder on the servomotor inFIG. 2part number31. Then using the laser sensor25inFIG. 2the computer will record the distance from the laser to the blade at point number one, then record it at another point number two. Using these recordings, a known calculation can now determine the pitch.

The data also will include the measured rake of a propeller. The rake is defined as the amount a blade is angled or bent in relation to the hub12and is displayed in degrees. The method and apparatus of the present invention uses a computer to determine rake by recording from the laser sensor25inFIG. 2the distance from the laser25to the blade at a point close to the hub12. Then those points that are in a straight line out from the hub at this point in each radii scan is then used to determine how much the blade is bent. The computer makes a known calculation to determine rake.

The data will also include the measured squareness of the propeller. The squareness is defined as the distance the blades are separated and is displayed in degrees. The method and apparatus of the present invention uses a computer to determine the squareness by recording from the encoder on the servomotor31inFIG. 2a particular point. Then it will record the same position on the next blade and calculate using these two points the curvature distance between the two points.

International Standard ISO 484/2 (UDC 629.12.037.1: 621.753.1 Ref. No. IS0 484/2-1981 (E)) is incorporated herein by reference, and explains how to calculate the data in the three preceding paragraphs.

Once a new “job” has been created, an operator enters the Auto Scan mode on the computer. The operator is then ready to begin a propeller scan. The operator will start the auto scan by pressing the Start Scan button on the Auto Scan screen. The measuring apparatus20will begin by moving the laser out on the linear axis to a first radii position that has been selected. The measuring apparatus20will then begin to rotate on the curved axis around the propeller11. The laser25will measure the distance from the laser head to the propeller11and a computer can be used to record these parameters as it rotates. Once the curved axis has reached 360 degrees it will reverse on the curved axis and return to its original home position at 0 degrees. Once it has reached 0 degrees or “home position” the linear axis will move the laser head to a different radii position and repeat the process. This process is continued until the laser has moved out to each of the radii positions pre-selected by the operator.

The method and apparatus of the present invention can be computer controlled, using software that is user-friendly enabling easy training of users. Software can be used by an operator to operate the apparatus10, collect data, and to report that data to a customer. In the computer screen shots ofFIGS. 5-10, fields that can be selected from a database using pull down menus. A user can start typing in a selected (e.g. light green) field and selectable information will begin to pop up in the pull down menu. As a user is typing, the information you are looking for comes up simply hit the enter key and that information will be entered in the field. The field that automatically pulls in information from a database and cannot have information typed in is another color, e.g. light gray fields. The field that information can be typed in or sometimes can also be selected from a pull down menu can be e.g. light red fields.

To create a new customer, click on the Customer tab45inFIG. 5. Under this tab there are four different icons. The first icon is the Browse Customer screen. This screen is used to view customers that have already been added to the database. The second icon is the Add Customer screen. This screen is used to add new customers to the database. The third icon is the Edit Customer screen. This screen is used to change information about a customer that is already in the database. The fourth icon is the Delete Customer screen. This screen is used to delete customers out of the database. These screens under the Customer tab45are similar to each other. Following is a review of one of these screens, the Add Customer screen.

Once a user has clicked on the Customer tab45then simply click on the Add Customer icon to create a new customer. The screen shown inFIG. 5will display and a new customer can be entered to the database. Simply click in the text boxes46inFIG. 5and enter the information about the new customer. Notice at the bottom of the screen the note47(* Indicates Required Fields) indicated inFIG. 5. Information must be entered in these fields before the software will allow a user to save this customer to the database. At the bottom of the screen indicated inFIG. 5is a box48that will allow entry of any selected personal notes48about this customer. This note48can be used to enter additional contact information, tax ID number or other desired information. Once the information is entered, a user clicks the Save New Customer49button indicated inFIG. 5. To exit the screen simply click the Exit button50.

To create a new job, simply click on the Prop Jobs tab51inFIG. 7. Once a user has clicked on the Prop Jobs tab51a user will notice three different icons. The first icon is the Browse Jobs screen. This screen is used to browse jobs that have already been done and is saved in the database. The second icon is the Create New Job screen. This screen is used to create a new job and prepare the system for auto scan (See Create New Job screen description following). A new job must be created in order to run auto scan, preparing the database and providing a place for the data to be collected and saved. The third icon is the Set Laser Reference screen. This screen is used to set the laser reference to insure accurate readings. This reference should be set only when the apparatus has been set on a new spindle or anytime the distance from the laser and the table below the prop has changed (See Set Laser Reference screen description following).

The laser reference is set so that the laser will ignore anything it reads beyond the propeller. First, ensure that the laser is measuring the closest item to the bottom of the propeller. The closest item to the bottom of the propeller can be e.g. a table under the propeller. To move the laser to this location go to the Manual Gage Control screen and turn the rotary motor31and traverse slide motor27off and pull the laser sensor25into location by hand or use the manual controls. Once the laser has been moved into position and a user has clicked the Prop Jobs tab, click the Set Laser Reference icon. The Set Laser Reference Surface screen ofFIG. 6will display. This screen (FIG. 6) shows two indicator boxes. The first box indicated inFIG. 6is the Current Reference52indicator. This indicator52will display the last reference set for the laser sensor25. The second box indicated inFIG. 6is the Laser Reading indicator53. This indicator53will display the actual reading of the laser and display the note indicated inFIG. 6as54.

To set the laser reference simply click the SET Laser Reference button55inFIG. 6. When this button is clicked the software will subtract 0.25 inches from what the laser is reading in the Laser Reading indicator box. The system will now ignore anything the laser measures beyond this point. To exit this screen simply click the Exit button56inFIG. 6.

Once a user has clicked on the Prop Jobs tab51, the user can click on the Create New Job icon and the Create New Prop Job screen will display. This screen is used to give the apparatus important information that is needed for auto scans. It prepares the databases and readies the system to collect data for the propeller about to be scanned. Notice at the bottom of the screen the note (* Indicates Required Fields) indicated inFIG. 7next to note57. Information must be entered in these fields before the software will allow this job to be saved. This screen has three parts the first of which is the Job Information58inFIG. 7. The second part is the Prop Information59. The third part is the Measurement Configuration60.

Job in formation58is used to enter selected information about the job. When the Customer is selected information such as the customers address, phone number, contact person is automatically pulled in from a database. If the customer you have is not listed then simply exit this screen and go to the Create New Customer screen and add the customer to the list. The software will automatically increment the Prop ID field by one number each time a new job is created. The text box61is a field where a user can enter notes in about this job.

Prop Information59is used to enter key information about the propeller11to be scanned. The diameter of the propeller11can be typed in or selected from the pull down menu. If a user does not know the diameter of the propeller, the user exits this screen and goes to the Manual Gage Control screen (FIG. 10) The user manually moves the laser sensor25out to the edge of the propeller11and read the radius of the propeller11from the Traverse Radius indicator box62. This reading is the radius of the propeller, so multiply this number by two and enter it in the Diameter field (See the description on the Manual Gage Control screen below for more information on moving the laser).

Measurement Configuration60is used to enter the measurement configuration for a job. When the desired class is selected the number of radii scans and the position of that radii scan (entered as percentage of the prop diameter) will automatically be entered and is according to the ISO standards for the selected class. Simply clicking the check box under each radii scan to add or take away radii scans can easily change this configuration. The check box is indicated inFIG. 7as63. A user can also change the position of the radii scan by simply clicking in the radii scan box64and typing in the desired position or selecting it from the pull down menu.

Once all the information has been entered in the three parts of the Create New Prop Job screen the job can be saved by clicking the Save New Job button65inFIG. 7. Notice the job information status bar66at the bottom of the screen inFIG. 7. This status bar66indicates what job has been loaded by the software and is current. This status bar66will remain throughout other screens such as the PropEye Auto Prop Scan screen and the Manual Gage Control screen to give a quick indication as to what job is loaded. To exit this screen simply click the Exit button67inFIG. 7.

To automatically scan a propeller, simply click on the PropEye Scan tab68inFIG. 8. Under this tab you will notice two icons. The first icon is the Automatic Scan screen. This screen is used to do a complete automatic scan of a propeller. This screen is described hereinafter in the PropEye Auto Prop Scan screen description. The second icon is the Quick Scan screen and is used to make quick individual scans of one blade while repairs are being made. This screen will allow a user to make adjustments and then scan what has been adjusted quickly.

Once the PropEye Scan tab68has been clicked, a user can display the PropEye Auto Prop Scan screen by clicking the Automatic Scan icon. This screen has six parts. The first is the Job Setup Parameters69inFIG. 8and is used to display and modify the job parameters. The second part is the Real Time Indicators part70inFIG. 8. This part70displays the current position of the apparatus and what the laser is measuring. The third part is the Gage Commands part71inFIG. 8. This part71is used to give the operator some control of the apparatus. The fourth part is the Repair Status part72inFIG. 8. This part72is used to give the operator a way to indicate in the report when this scan was made during the repair process. The fifth part is the Repair Status/Results part73inFIG. 8. This part73takes up most of the screen and is broken down for easier viewing. The sixth part is the message box74inFIG. 8. This part74will let the operator know what the machine is currently doing or what it is ready to do.

Job Setup Parameters69is used to indicate and modify the job parameters. This part69will display information about the current job that has been loaded into the system and is ready to collect data. This information will include the Customer name, ID number and some information about the prop being scanned. Some of this information can be changed. Clicking in the Diameter or Pitch boxes and either typing in the change or selecting it from a pull down menu can change the diameter and pitch values. Clicking the Class box and selecting the desired change from a pull down menu can change the Class value. Clicking in the desired Radius box and either typing or selecting from a pull down menu the radius values can be changed or radiuses can be added or deleted.

Real Time Indicators70displays the current position of the apparatus and what the laser sensor25is measuring. These displayed values are real time and will give the operator a quick visual as to where the apparatus is located in relation to the propeller11.

Gage Commands71is used to give the operator some control of the apparatus20. The Motor OFF and Motor ON commands are used to turn the rotator servo motor31on and off. By clicking the Motor OFF command the operator can turn the motor31off and then rotate the laser sensor25around by hand to a desired position then by clicking the Motor ON command the operator can turn the motor31back on. This will help the operator to place the laser25to a desired position before starting an automatic scan. For example, the laser sensor25can be turned off, rotated to a position before a selected blade and then turned on again. Once in the desired position the operator by clicking the Motor ZERO command can zero out the position of the rotator servomotor31making this the new home position. The operator by clicking the Motor HOME command can send the laser to the home position. The operator by clicking the START SCAN command can begin an auto scan of the prop.

Repair Status72is used to give the operator a way to indicate in the report when this scan was made during the repair process. The report when printed will indicate which of these check boxes was clicked.

Repair Status/Results73takes up most of the screen and is broken down for easier viewing. Clicking the desired display in the View Select 75 part indicated inFIG. 9can change the results displayed in this part. By clicking the Graphs/Charts box then selecting from a pull down menu by clicking the Graph Type box the display can be changed to display a PolarPlot, BarChart or a LineChart.FIG. 8is shown displaying Tubular Data as per selected in the View Select part75.FIG. 9is shown as displaying a bar chart as per selected in the View Select part indicated inFIGS. 8 and 9next to note A.

Message Box74informs the operator what the machine is currently doing or what it is ready to do. In the displays shown inFIGS. 8 and 9, the message (Press [START SCAN] to Measure the Propeller) is displayed and lets the operator know the system is ready to begin an automatic scan.

To operate the apparatus20manually simply click on the Manual76tab inFIG. 10. Under this tab is found the Manual Operation icon. Clicking this icon the Manual Gage Control screen will display. The Manual Gage Control Screen Description screen is broken down into three parts. The first part is the Laser Rotate Axis77part inFIG. 10enabling operator to command the rotary axis of the apparatus20. The second part is the Laser Traverse Axis78. The operator to command the traverse slide of the apparatus uses this part. The third part is the Laser Displacement79part inFIG. 10. The operator can use the laser value to calculate the pitch between two points using this part of the apparatus.

The Laser Rotate Axis77is divided into three parts and is used by the operator to command the rotary axis of the apparatus20. The Rotary Master Commands part80inFIG. 10is used for the following functions: 1) Motor ON turns the rotary servomotor motor31on; 2) Motor OFF turns the rotary servomotor motor31off; 3) Motor STOP stops the rotary servomotor31when it is in motion; 4) Motor ZERO will zero the position of the rotary servomotor31making this position the home position; 5) Motor HOME will cause the rotary servomotor31to move to the home position; and 6) Select Speed will allow the operator to change the speed of the rotary servomotor31by selecting the speed from a pull down menu.

The Rotary Motion81part inFIG. 10is used for the following functions: 1) Jog CW jogs the rotary servomotor31in the clockwise direction; 2) Jog CCW jogs the rotary servomotor31in the counterclockwise direction. Notice the hint box82over this command indicated inFIG. 10. When the operator places the mouse over a command a hint box giving some description as to what this command does will display; 3) Move to Position will run the rotary servomotor31to the position entered in the Enter Angle box or the Select Angle box; 4) Memory commands when clicked will store the position of the rotary servomotor31. By clicking the Recall command under the Memory commands the rotary servomotor will move to the point that was stored. The operator can record and recall 5 different positions.

The Rotary Angle83display indicated inFIG. 10simply displays the current position of the rotary servomotor.

The Laser Traverse Axis84inFIG. 10is divided into three parts and is used by the operator to command traverse axis of the apparatus. The Traverse Master Commands85part is indicated inFIG. 10is used for the following functions: 1) Slide ON turns the traverse slide motor27on; 2) Slide OFF turns the traverse slide motor27off; 3) Slide STOP stops the traverse slide motor when it is in motion; 4) Slide HOME will cause the traverse slide motor27to move to the home position; and 5) Select Speed will allow the operator to change the speed of the traverse slide26by selecting the speed from a pull down menu.

The Traverse Motion86part inFIG. 10is used for the following functions: 1) Jog IN jogs the traverse slide bracket28in toward the hub of the propeller11; 2) Jog OUT jogs the traverse slide bracket28out away from the hub12of the propeller11; 3) Enter Diameter box allows the operator to enter or select from a pull down menu the diameter of the propeller11being repaired; and 4) Move to Position will run the traverse slide bracket28to the position entered in the Enter Radius box or the Select Radii % box.

The Traverse Radius display62inFIG. 10simply displays the current position of the traverse slide26. The operator can use this display to find the diameter of the prop if it is not known. It is recommended that the operator jog the laser sensor25by using the jog commands for the rotary servomotor31and traverse slide motor27to the edge of the blade13,14,15,16. The operator can also turn the rotary servomotor31and traverse slide motor27off and pull the laser sensor25out to the edge of the propeller11by hand. Once in this position the value is shown in this display. The value in this display is measuring the radius of the propeller11so the operator will need to multiply this value by two (2) to achieve the diameter of the propeller11.

The Laser Displacement79inFIG. 10has a laser measurement display and a quick pitch measurement from two points. The Mem P1and Mem P2indicated inFIG. 10commands87are used to store the laser measurement and position of the rotary servomotor31between two points. Once these two points was stored in memory then the operator can click on the Cal Pitch inFIG. 10and the pitch between these two points will be calculated and displayed in the box89inFIG. 10. The Clear button when clicked will clear the memory of the two points that has been stored.