Patent US3987272A successfully refreshed from Google Patents.
US3987272A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Manufacture of forks for fork lift trucks
Assignee: Lancer Boss Ltd
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Filing: 1974-06-24
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Granted: 1976-10-19
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Expires: 1994-06-24
Abstract
Abstract A method of producing from straight metal section material fork lift truck forks of substantially L-shaped construction with substantially vertical and horizontal arm portions extending from the bend, comprising heating the straight metal to softening point in the region of the proposed bend and while the vertical and horizontal arm portions are supported substantially at right angles, forming with softened metal by cavity welding the required shape of the fork in the region of the bend.
Inventors
- 👤 Godfrey Alfred Stevens
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 10:30
CPC Classifications
B; B66; B66F; B66F9/00; B66F9/06; B66F9/075; B66F9/12
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
180 words
A method for producing from straight metal section material fork lift truck forks of substantially L-shaped construction having large and very strong substantially horizontal and vertical arm portions for lifting massive loads, comprising providing from a rolled steel strip having a substantial sized cross section of the desired fork two arm portions, disposing the ends of said arm portions in contiguous substantially perpendicular relationship with an air gap between them, masking said gap to form an enclosed cavity, introducing into said cavity at least one tubular guide of welding material and passing a wire of welding material through said guide into said cavity, passing a high frequency electric current through said welding material of at least one of said guide and said wire to soften said welding material so that it flows to fill said cavity and softens said contiguous ends of said arms to form a solid and very strong union between said arms with welding material shaped by said masking to form said union between said arms, and thereafter normalizing and tempering the metal of the formed fork.
Claim 2
Independent Claim
180 words
A method for producing from straight metal section material fork lift truck forks of substantially L-shaped construction having large and very strong substantially horizontal and vertical arm portions for lifting massive loads, comprising providing from a rolled steel strip having a substantial sized cross section of the desired fork two arm portions, disposing the ends of said arm portions in contiguous substantially perpendicular relationship with an air gap between them, masking said gap to form an enclosed cavity, introducing into said cavity at least one tubular guide of welding material and passing a wire of welding material through said guide into said cavity, passing a high frequency electric current through said welding material of at least one of said guide and said wire to soften said welding material so that it flows to fill said cavity and softens said contiguous ends of said arms to form a solid and very strong union between said arms with welding material shaped by said masking to form said union between said arms, and thereafter normalizing and tempering the metal of the formed fork.
Claim 3
Dependent Claim
44 words
A method according to claim 1 wherein said strip material is of EN 24 steel having substantially the following percentage composition by weight C, 0.40; Si, 0.26; Mn, 0.29; Ni, 1.39; Cr, 1.11; Mo, 0.23; S, 0.005 and P, 0.011, the remainder being Fe.
Claim 4
Dependent Claim
35 words
A method according to claim 1 wherein said strips are of 127 × 304 mm steel with mitred ends and said strips are supported with said gap between said mitred ends being 32 mm wide.
Claim 5
Dependent Claim
30 words
A method according to claim 1 wherein said wire is of 3.2 mm SD3 21/2Cr 1 Mo metal used with a flux selected from Rowen Arc AN8 and Esab 10.50.
Claim 6
Dependent Claim
23 words
A method according to claim 1 wherein the Ni content in said welding material is not in excess of 2.7 percent by weight.
Claim 7
Dependent Claim
52 words
A method according to claim 1 wherein the heat treatment is ______________________________________
EN 24
Normalising 820-850° C/2 hours - Air cool
Normalising and
820-850° C/2 hours - Air cool
temper 650° C/3 hours - Air cool
Quench and 820-850° C/2 hours - Oil quench
temper 650° C/3 hours - Air cool.
______________________________________
Claim 8
Dependent Claim
64 words
A method according to claim 1 wherein said strips are of Superelso 70 steel having a composition of percentage by weight of C, 0.18; Si, 0.38; Mn, 1.39; Ni, 0.83; Cr, 0.73; Mo, 0.23; S, 0.015; P, 0.010; Cn, 0.48, the remainder being Fe, said strips being of 304 × 608 × 32 mm section separated by said gap which is 32 mm wide.
Claim 9
Dependent Claim
36 words
A method according to claim 1 wherein the heat treatments used are ______________________________________
Normalising 900° C/11/4 hours - Air cool
Quench and 900° C/11/4 hours - Water quench
temper 600° C/1 hour - Air cool.
______________________________________
Claim 10
Dependent Claim
29 words
A method according to claim 1 wherein said union being formed is percentage by weight substantially Mn, 1.0; Ni, 2.5; Cr, 1.6; Mo, 0.5, and the remainder being Fe.
Claim 11
Dependent Claim
66 words
A method in accordance with claim 1 wherein said union being formed comprises not more than about 0.30 percent by weight carbon, not more than about 2.7 percent by weight nickel, about 0.2 percent by weight silicon, about 0.85 percent to 1.0 percent by weight manganese, about 1.6 percent to 1.8 percent chromium, about 0.5 percent to 0.6 percent by weight molybdenum, the remainder being iron.
Claim 12
Dependent Claim
16 words
A process in accordance with claim 1 further comprising quenching said fork after normalizing and tempering.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-10-19 | 1980-04-19 | 1980-10-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-10-19 | 1984-04-19 | 1984-10-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-10-19 | 1988-04-19 | 1988-10-19 | $7700.00 | Window Closed / Lapsed |