For the Inventor, By the Inventor

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Torrance, CA, United States of America

Grefco, Inc.

USPTO Granted Patents = 23

Forward Citations = 601

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19 inventors (with patents filed for the assignee):

David L Ruff (9 out of 11 patents)

Harlan E Tarbell (5 out of 5 patents)

Richard B Nielsen (5 out of 6 patents)

4. Sherman A Stewart (4 out of 4 patents)

5. Estel R Snyder (3 out of 3 patents)

6. Melvin J Mirliss (2 out of 3 patents)

7. Ernest L Neu (2 out of 2 patents)

8. Paul J Raabe (2 out of 2 patents)

9. Charles J Vogelsang (2 out of 2 patents)

10. N Gokul Nath (2 out of 2 patents)

11. Narikottile G Nath (1 out of 3 patents)

12. William R White (1 out of 1 patent)

13. Donald W Mogg (1 out of 2 patents)

14. Otto A Oshida (1 out of 1 patent)

15. John B Gilmour (1 out of 2 patents)

23 patents: Sort by Forward Citations

1. 5002696 - Expanded mineral particles and apparatus and method of production (1991-03-26),

2. 4671973 - Method for the treatment of mineral extender fillers (1987-06-09),

3. 4521182 - Method and apparatus for heating particulate material (1985-06-04),

4. 4313997 - Perlite boards and method for making same (1982-02-02),

5. 4302344 - Loose-fill, thermal insulation (1981-11-24),

6. 4255489 - Perlite filler (1981-03-10),

7. 4212755 - Settle resistant loose-fill perlite insulation comprising particles (1980-07-15),

8. 4187174 - Diatomaceous earth filteraid and method for its manufacture (1980-02-05),

9. 4183980 - Perlite filler coated with polydimethylsiloxane (1980-01-15),

10. 4145284 - Method for making polymeric filter aids and products thereof (1979-03-20),

11. 4142968 - Diatomaceous earth filteraid and method for its manufacture (1979-03-06),

12. 4110501 - Splicing strip (1978-08-29),

13. 4073673 - Process for producing an expansion joint cover (1978-02-14),

14. 4071993 - Construction material in sheet form and method of joining sheets (1978-02-07),

15. 4067155 - Sealing system (1978-01-10),

Company Overview

Grefco, Inc. is a Torrance, California-based company specializing in advanced engineering and manufacturing solutions. The organization focuses on developing innovative products and technologies primarily for the aerospace and defense sectors. Grefco is known for its expertise in precision machining, assembly, and testing, catering to a diverse range of clients with high-quality standards. Through its commitment to research and development, Grefco continues to enhance its capabilities and contribute to advancements in engineering solutions.

Profile summary synthesized from public USPTO records and patent filings.

Company Badge

USPTO Data Jan 1 1976 - Oct 6 2026

23 Patents

#22 in Torrance, CA

#3,416 in California

#14,415 in US

#27,649 in the World

Torrance, CA, United States of America

Grefco, Inc.

Forward Citations = 601

19 inventors:

David L Ruff (9 out of 11 patents)

Harlan E Tarbell (5 out of 5 patents)

Richard B Nielsen (5 out of 6 patents)

4. Sherman A Stewart (4 out of 4 patents)

5. Estel R Snyder (3 out of 3 patents)

IDiyas Innovation Intelligence. (2026). Company Patent Portfolio: Grefco, Inc.. Retrieved from https://idiyas.com/company/grefco

Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile

Data Sources: USPTO Patent Grant XML, Patent Center, EPO & CIPO • Normalized by IDiyas Innovation Graph. Methodology & provenance architecturePlease report any incorrect information to [email protected]

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