SLEEVE CONE QUALITY MEASUREMENT SYSTEM AND METHOD

• US 20100094587A1
• Filed: 10/15/2008
• Published: 04/15/2010
• Est. Priority Date: 10/15/2008
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Leuthold, Hans, Berry, Reid E. II, Gonzalez, Steve G., Mysore, Ananda V.
• Granted Patent: US 7,885,786 B2
• Time in Patent Office: Days
• US Class Current: 702/155
• CPC Class Codes: G01B 5/008 using coordinate measuring machines

Abstract

A metrology system for measuring a cone angle, a cone straightness, and a cone quality of a sample and method of using the metrology system are disclosed. The system includes a rotary stage, one or more workpiece fixtures that hold the samples in the rotary stage, and a number of different sized measurement devices. The measuring devices are positioned next to the rotary stage and measure the samples using contact. The rotary stage is free to rotate when the measuring devices are in a non-measuring state. The invention also includes a processor that collects data from the measurement devices and calculates the cone angle, the cone straightness, and the cone quality of each sample based on the data.

Claims

1. A metrology system comprising:

a rotary stage;

at least one holding fixture, each for holding at least one conical sample;

a plurality of differently sized measurement devices positioned adjacent to the rotary stage for interfitting, in a measuring state, with the samples to obtain data useful in determining one or more characteristics of the samples, wherein the rotary stage is free to rotate when the measuring devices are in a non-measuring state; and

a processor in communication with the measurement devices, and operable to use the data from the measurement devices for calculating a cone angle, a cone straightness, and a cone quality of each sample.

2. The metrology system of claim 1, wherein each measurement device includes:

a contact element for the interfitting with the samples;

a plunger coupled to the contact element and operable to extend the contact element towards the samples; and

a gauge adapted to measure the extension of the plunger after contact by the contact element with the sample.

3. The metrology system of claim 2, further comprising a gauge controller for controlling the measuring devices, and a stage controller for controlling the rotary stage, wherein the processor coordinates the gauge controller and the stage controller.

4. The metrology system of claim 2, further comprising a plunger controller, wherein the plunger controller is operable to use air pressure for extending each plunger and to use vacuum to retract each plunger.

5. The metrology system of claim 2, wherein a shape of the contact element is from a group consisting of a sphere and a hemisphere.

6. The metrology system of claim 5, wherein each measurement device contact element has a diameter different than respective diameters of the contact elements of other measuring devices.

7. The metrology system of claim 2, wherein there are three or more measurement devices, and cone quality and straightness are calculated using differences between respective contact element radii and radii calculated using measured extension of its plunger after contacting each sample.

8. The metrology system of claim 2, wherein the gauge is adapted to measure the extension of the plunger after sample alignment caused by an initial contact between the contact element and the sample, which may result in further extension of the plunger from an initial contact point.

9. The metrology system of claim 1, wherein each sample includes a sleeve cone.

10. The metrology system of claim 1, wherein the rotary stage is supported by an air bearing.

11. The metrology system of claim 1, wherein each holding fixture comprises a sample slot which comprises a low friction surface for supporting each sample and allowing the sample limited movement within the sample slot.

12. The metrology system of claim 11, wherein the low friction surface comprises surface at least partially formed of sapphire.

13. The metrology system of claim 1, further comprising a calibration block for calibrating the plurality of measuring devices.

14. The metrology system of claim 13, wherein the calibration block is positioned within a sample slot.

15. The metrology system of claim 1, wherein the cone angle is determined using a Least Squares fit mathematical model.

16. The metrology system of claim 1, wherein a plurality of samples are measured simultaneously.

17. The metrology system of claim 1, wherein the cone quality is determined using an R-squared calculation.

18. A metrology method, comprising the steps of:

(a) placing at least one sample into at least one sample slot, wherein each sample slot is arranged within a rotary stage;

(b) extending a measuring device to contact with each sample and recording an amount of extension of each measuring device, wherein there are a plurality of different sized measuring devices;

(c) retracting the measuring devices;

(d) rotating the rotary stage to a subsequent position wherein at least one sample slot is aligned with another measuring device;

(e) repeating steps (b) through (d) until each sample is measured by each measuring device;

(f) compiling a data set of data from the recorded extension of each measuring device for each sample; and

(g) calculating a cone angle, cone straightness, and cone quality of each sample based on the compiled set of data.

19. The method of claim 18, further comprising the step of calibrating each measuring device.

20. The method of claim 18, further comprising the steps of:

determining if any of the plurality of samples are defective; and

alerting a user about any defective samples.

21. The method of claim 18, wherein the cone quality is determined using an R-squared parameter.

22. The method of claim 18, wherein a plurality of samples are measured simultaneously.