DESC:FIELD OF INVENTION

This invention relates to an apparatus for an Automatic Gear DFCE Measurement Machine with lead error detection.

BACKGROUND OF INVENTION:

Normally precision gears are checked for gear teeth accuracy by measuring DFCE (Double Flank Composite Error). To check this, a gear is engaged with a master gear of higher accuracy and rotated by 360 degrees. A center distance between gear and master gear are measured continuously and its variation is used to calculate DFCE.
In current process of checking DFCE and lead error is with Solid locator. DFCE cannot be measured accurately with this method. Also, manual intervention needs to be avoided to eliminate chances of dent & damages during load / unload. (Refer Figure.1).

Other known prior art concepts was clamping of gear from the top with a solid locator as shown in figure 2. But this involves more number of components & more clearance between component and solid locator. Loading from top using robot is also difficult. So this concept is not used.

With the above devices, gears with more lead error are supplied to engine assembly and thereby leading to engine noise which is undesirable.

OBJECT OF THE INVENTION :

The first object of the invention is to develop inspection equipment to measure DFCE and lead error of the gear and to make it compatible for automatic operation thereby avoiding human intervention and preventing dent and damages in the inspection process.
Another objective of the invention is to improve the accuracy and productivity of gear parameters measurements.

SUMMARY

With this object in view, the present invention provides an apparatus for DFCE (double flank composite error) measurement of a gear comprising:
a. a first clamping means for removably clamping the gear,
b. a second clamping means for removably clamping a master gear,
c. a drive means for rotating the master gear and the gear.
d. a measuring means for measuring double flank composite error.

An apparatus for lead error measurement of a gear comprising:
a. a first clamping means for removably clamping the gear,
b. a second clamping means for removably clamping a master gear ,
c. a drive means for rotating the master gear and the gear .
d. a measuring means for measuring lead error.

The apparatus for DFCE and lead error measurement of a gear further comprising:
a. a sensor means for sensing the tooth orientation of gear and master gear and controllably operating the drive means to rotate the master gear in a specific orientation,
b. an engaging means to move the gear and engage the gear with the master gear ,
c. a measuring means for measuring double flank composite error and lead error values during the rotational motion of the engaged gear and master gear for a at least 360° rotation path.
wherein; the DFCE and lead error are measured at the same instant and with same setup.

Preferably in the said apparatus for DFCE and lead error measurement of a gear; the first clamping means is a collet operable with disc spring , spindle shaft and pneumatic cylinder and the gear is clamped and de-clamped by axial movement of spindle shaft with the help of pneumatic cylinder .
Preferably in the said apparatus for DFCE and lead error measurement of a gear; the second clamping means comprises spindle shaft 31 on which a master gear is clamped by fastening means ; and a servo motor which rotates the spindle shaft along with master gear .
Preferably in the said apparatus for DFCE and lead error measurement of a gear; the drive means is a servo motor.
Preferably in the said apparatus for DFCE and lead error measurement of a gear; the sensor means is an analog sensor.
Preferably in the said apparatus for DFCE and lead error measurement of a gear; the measuring means is a LVDT probe operable by a slide onto which the master gear spindle is mounted,
Preferably in the said apparatus for DFCE and lead error measurement of a gear comprising, a control unit for receiving the measured inputs from the measuring means and storing there within and calculating the DFCE and lead error wherein; the control unit is a PLC (Programmable Logic Controller).
Preferably in the said apparatus for DFCE and lead error measurement of a gear; control unit measures current drawn by servo motor during rotation of gear engaged with master gear.
Preferably in the said apparatus for DFCE and lead error measurement of a gear; the engaging means is a pneumatic cylinder which moves the slide onto which gear spindle is mounted.
Preferably in the said apparatus for DFCE and lead error measurement of a gear, a display means which displays the measured DFCE values or lead error value or both values
wherein; the display means is a MMI (Man Machine Interface).
Preferably in the said apparatus for DFCE and lead error measurement of a gear, the servo motor rotates the master gear in a specific orientation which is corresponding to the tooth orientation of gear to avoid collision between respective tooth of master gear and gear.
A method of measurement of DFCE and lead error of a gear with an apparatus comprising:
a. clamping a gear by a first clamping means ,
b. clamping a master gear by a second clamping means ,
c. rotating the master gear and the gear by a drive means .
d. sensing a tooth orientation of the gear and the master gear by a sensor means and controllably operating the the drive means to rotate the master gear in a specific orientation,
e. moving the gear by a slidably engaging means and engage the gear with the master gear ,
f. measuring double flank composite error and/or lead error values during the rotational motion of the engaged gear and the master gear for at least 0° rotation path by a measuring means .
g. receiving the measured inputs from the measuring means and storing there within and calculating the DFCE and lead error by a control unit ,
h. displaying the measured DFCE and / or lead error values on display means ,
Preferably in the said apparatus for DFCE and lead error measurement of a gear, loading and unloading of gear may be done using Robot without human intervention.

DESCRIPTION OF DRAWINGS

Figure.1 is a prior art manual method for checking of gear DFCE value by using solid locators.

Figure. 2 is an prior art method for checking of gear DFCE value by clamping gear from top side with solid locators.

Figure. 3 is overall layout of the apparatus according to the invention.
Figure. 3a is a top view of Figure. 3a in gear engage condition.
Figure. 3b is a top view of Figure. 3a in gear disengage condition
Figure. 3c is a isometric view of Figure. 3a.
Figure. 4 is an exploded view of first clamping means.
Figure. 5 is an exploded view of second clamping means.

DESCRIPTION OF THE INVENTION:

Referring to figures 1 and 2, in one prior art arrangement of gear tester, master gear 11 and gear 12 are located on solid locators. In another prior art arrangement, a gear 12 is clamped by top clamp 13. DFCE cannot be measured accurately with this methods. Also these requires more number of parts and automation of loading unloading is difficult.

Auto gear DFCE (Double flank composite error) and lead error detection measuring machine as per the invention is described below.

Referring to figures 3 to 5, the apparatus for measuring DFCE and lead error comprises two clamping means. First clamping means 20 comprises a collet 21 operable with disc spring 22, spindle shaft 23 and pneumatic cylinder 24. A gear 12 is manually loaded on it and is clamped on its bore by collet 21 and hold in its position by disc spring 22. The gear 12 is clamped and declamped by axial movement of spindle shaft 23 with the help of pneumatic cylinder 24. For example, the gear 12 is clamped by pulling down the collet 21 by disc spring 22 and is declamped by pushing up the collet 22 by pneumatic cylinder 24. Second clamping means 30 comprises a spindle shaft 31 and drive means 32(for example servo motor). A master gears 11 is manually loaded on it and is clamped to the spindle shaft 31 at fixed position with the help of dowel pin 17 and fastening means (for example) nut 34. Teeth orientation of gear 12 is sensed by sensing means 14 (for example analog sensor) accordingly master gear 11 is rotated by a servo motor 32, to achieve exact orientation of the gear tooth with respect to the master gear tooth to avoid collision between them.
Once exact orientation is achieved, the slide 25 on which gear 12 is mounted moves forward to a checking position by engaging means 16 (For example pneumatic cylinder) and the gear 12 gets engaged with the master gear 11.
Master gear 11 is then rotated by servo motor 32. Due to engagement of teeth, a gear 12 is also rotated for fixed rotation (for example more than 360 degrees) and during this rotation, a center distance between gear 12 and master gear 11 is measured with the help of measuring means 15 (For example - LVDT or Linear Variable Differential Transducer). An electric current drawn by the servo motor 32 during rotation of engaged gears is measured by control unit. The measured values of center distance and current drawn are stored in storage means (For example - PLC or Programmable Logic Controller). The measured values are taken for more than 360 degree rotation of gear, but all middle set of values of 360 degrees rotation are consider for calculations.
For example, in case the gear is rotated by 432 degrees, the values of first 36 degrees and last 36 degrees are not considered for calculation of DFCE and lead error, and all middle set values of 360 degrees are considered for calculation. DFCE is calculated with the measured value of center distance and lead error is calculated with the measured value of drawn current. These calculations are done for with the help of standard formulas which are already saved in PLC. The calculated values are displayed on the display means 35 (For example - MMI - Man Machine Interface).

In another aspect, the DFCE and lead error are measured at the same time and with same setup.

In another aspect the loading and unloading of gear may be done using Robot without human intervention.

With the above method the accuracy and productivity of gear measurement will improve. The measured data shows that the cycle time for inspection of one gear is reduced by 3.5 seconds with this invention which improves productivity by 21%. Also the data shows that the repeatability of inspection results are improved by 15% with the use of this invention.

All variations and modifications obvious to the skilled persons are within the scope of the invention.
,CLAIMS:1. An apparatus 10 for DFCE (double flank composite error) measurement of a gear 12, wherein; the apparatus 10comprising:
a. a first clamping means 20 for removably clamping the gear 12;
b. a second clamping means 30 for removably clamping a master gear 11;
c. a drive means 32 for rotating the master gear 11 and the gear 12; and
d. a measuring means 15 for measuring double flank composite error.

2. An apparatus 10 for lead error measurement of a gear 12, wherein; the apparatus 10 comprising:
a. a first clamping means 20 for removably clamping the gear 12;
b. a second clamping means 30 for removably clamping a master gear 11;
c. a drive means 32 for rotating the master gear 11 and the gear 12; and
d. a measuring means 15 for measuring lead error.

3. The apparatus 10 as claimed in claim 1 or 2, further comprising:
a. a sensor means 14 for sensing tooth orientation of the gear 12 and the master gear 11 and controllably operating the drive means 32 to rotate the master gear 11 in a specific orientation;
b. an engaging means 16 to move and engage the gear 12 with the master gear 11;
c. a measuring means 15 for measuring double flank composite error and lead error values during the rotational motion of the engaged gear 12 and master gear 11 for at least 360° rotation path; and
wherein the DFCE and lead error are measured at the same instant and with same setup.

4. The apparatus 10 as claimed in claim 3, wherein the first clamping means 20 is a collet 21 operable with a disc spring 22, a spindle shaft 23 and a pneumatic cylinder 24 and the gear 12 is clamped and de-clamped by axial movement of the spindle shaft 23 with the help of the pneumatic cylinder 24.

5. The apparatus 10 as claimed in claim 3, wherein the second clamping means 30 comprises a spindle shaft 31 on which the master gear 11 is clamped by a fastening means 34 and a servo motor 32 which rotates the spindle shaft 31 along with the master gear 11.
6. The apparatus 10 as claimed in claim 3, wherein the drive means 32 is the servo motor 32.
7. The apparatus 10 as claimed in claim 3 wherein; the sensor means 14 is an analog sensor .
8. The apparatus 10 as claimed in claim 3, wherein the measuring means 15 is a LVDT probe operable by a slide 25 onto which the master gear spindle 31 is mounted.
9. The apparatus 10 as claimed in claim 3, further comprising, a control unit 33 for receiving the measured inputs from the measuring means 15 and storing there within and calculating the DFCE and lead error,
wherein; the control unit 33 is a PLC (Programmable Logic Controller).
10. The apparatus 10 as claimed in claim 9, wherein the control unit 33 measures current drawn by the servo motor 32 during rotation of the gear 12 engaged with the master gear 11.
11. The apparatus 10 as claimed in claim 3, wherein the engaging means 16 is a pneumatic cylinder which moves the slide 25 onto which the gear spindle 23 is mounted.
12. The apparatus 10 as claimed in claim 3 , further comprising a display means 35 which displays the measured DFCE values or lead error value or both values and
wherein the display means 35 is a MMI (Man Machine Interface).
13. The apparatus 10 as claimed in claim 5, wherein the servo motor 32 rotates the master gear 11 in a specific orientation which is corresponding to the tooth orientation of the gear 12 to avoid collision between respective tooth of the master gear 11 and the gear 12.
14. A method for measurement of DFCE and lead error of a gear with an apparatus 10, wherein; the method comprising:
a. clamping a gear 12 by a first clamping means 20;
b. clamping a master gear 11 by a second clamping means 30;
c. rotating the master gear 11 and the gear 12 by a drive means 32;
d. sensing a tooth orientation of the gear 12 and the master gear 11 by a sensor means 14 and controllably operating the drive means 32 to rotate the master gear 11 in a specific orientation;
e. moving the gear 12 by a slidably engaging means 16 and engage the gear 12 with the master gear 11;
f. measuring double flank composite error and/or lead error values during the rotational motion of the engaged gear 12 and the master gear 11 for at least 360° rotation path by a measuring means 15;
g. receiving the measured inputs from the measuring means 15 and storing there within and calculating the DFCE and lead error by a control unit 33; and
h. displaying the measured DFCE and / or lead error values on display means 35,
15. The apparatus and the method as claimed in any of the above claims, wherein loading and unloading of gear 12 may be done using Robot without human intervention.