At a glance
| Patent number | CN105538206B (application CN201610116032) |
| Type | China invention patent (发明专利) - examined; protects the technical solution |
| Original title | Combination wrench for external hex bolts and nuts (一种用于外六角螺栓、螺母的组合扳手) |
| Patent owner | Shaanxi University of Technology |
| Inventors | Hou Hongling |
| Filing date | 2016-03-01 |
| Grant date | 2017-06-30 |
| Status (China) | Lapsed - terminated for non-payment of annual fees (recorded 2019-03-01) |
| Patent family | Chinese filings only - no US, European, Japanese, PCT or other filings listed |
| Cited by | 2 later documents |
| Source | Google Patents (search for CN105538206B) |
What the claims cover, in plain language
Claim 1 - a wrench with a handle whose end is a ring with flat faces; a toothed sleeve enclosed in the ring by lower and upper press rings screwed to the faces; a hex insert group in the sleeve; a pawl on a pin pressing against the insert group; and a shift fork on the handle near the ring. The sleeve has a regular-hexagon inside and rectangular teeth all round its outside. The insert group is a set of nested hexagonal tubes: the largest tube’s outside matches the sleeve’s inside, each tube’s inside matches the next smaller tube’s outside, and each tube’s inside fits one bolt or nut size. Each tube has a round-hole cover on the side away from the pawl.
Claim 2 - the handle’s other end is a stepped round section with a knurled end. Claim 3 - the sleeve’s teeth have equal tooth width and gap width.
This is a simplified reading for orientation only. The legal scope is defined by the exact claim wording in the official Chinese document.
What this means for US production
This patent was filed only in China and has lapsed, so it no longer restricts anyone in China either. It has no US or other foreign counterpart.
Two points to settle early:
- Other patents may exist. Multi-size wrenches - stepped sockets, spring-pin universal sockets and adjustable ring wrenches - are widely patented by US tool brands, and US design patents protect many wrench head shapes, so a freedom-to-operate (FTO) review should come before tooling.
- Wall thickness versus torque. Nested inserts are thin by nature; the size range per head and the steel grade decide what torque each size can safely take. This is set in design and verified by torque testing.
Customization and manufacturing
What can be customized
| Area | Options |
|---|---|
| Size range | Metric, SAE or mixed stacks; 3-6 sizes per head |
| Material | Chrome-vanadium or chrome-molybdenum steel inserts, forged handle |
| Finish | Chrome plating, black oxide, laser-marked size on each insert |
| Drive | Fixed fork drive, or a reversible ratcheting pawl |
| Handle | Length, bi-material grip, hanging hole |
| Packaging | Blister card, roll-up pouch, gift box |
Things to plan for (US market)
- ASME B107 hand-tool standards - professional buyers expect wrench and socket performance to ASME B107 (for example B107.100 for wrenches) proof-torque levels; we test against the agreed standard.
- Country-of-origin marking - hand tools must be marked with the country of origin, ideally on the tool itself.
- California Prop 65 - plated finishes and grips should be tested for lead and other listed substances.
- Size marking accuracy - each insert’s size must be marked and fit to standard tolerances.
How a project runs
- Inquiry - size range, steel, finish, packaging and quantity.
- Design - insert wall thickness, sleeve and press rings, drive type.
- Prototype - samples tested for fit, proof torque and insert retention.
- Pilot run - small batch for plating, marking and packaging checks.
- Production - volume production, packaging and shipping.
Quantities & timeline
The handle needs a forging die, the inserts need cold-forming or broaching and heat treatment, the sleeve teeth need machining or powder-metal tooling, and plating and laser marking need set-up. Most development time goes into insert wall strength. Send us your size range, steel grade, finish, quantity and target price and we will reply with options.
Patent drawings
Drawings reproduced from the public patent document for reference.
