At a glance
| Patent number | CN108422779B (application CN201810596119) |
| Type | China invention patent (发明专利) - protects method and structure |
| Original title | Adjustable hob rest of pencil sharpener (一种可调节的削笔器滚刀刀架) |
| Patent owner | Individual |
| Inventors | Zheng Gaowei |
| Filing date | 2018-06-11 |
| Grant date | 2023-07-25 |
| Status (China) | In force until at most 2038-06-11 (if annual fees are paid) |
| Patent family | Chinese filings only - no US, European, Japanese, PCT or other filings listed |
| Cited by | 0 later documents |
| Source | Google Patents (search for CN108422779B) |
What the claims cover, in plain language
Claim 1 - an adjustable hob rest comprising a tool rest with a planing opening, a limiting block with a conical abutting groove positioned below the opening, and a driving piece (specifically a rotary disk) at the lower end. The disk drives the limiting block vertically. The disk has a clamping piece with an irregular inner wall; the hob’s lower shaft is held against this wall by an elastic piece. Rotation changes the radial distance of the shaft, altering the hob’s inclination angle.
Claim 2 - adds a pencil blocking block with a shaft and multiple staggered blocking members. A gear on the shaft meshes with teeth on the rotary disk, so rotating the disk selects different blocking members for the planing opening.
Claim 3 - specifies the blocking members comprise a propping block and a clamping block with an inward concave arc surface to fit the pencil neck.
Claim 4 - details the connection of the hob shaft upper end to the hob frame.
Claim 5 - describes the limiting block as U-shaped, sleeved on the tool rest, moving along a vertical guide bar.
Claim 6 - defines the interface between the limiting block and disk: the block has an inclined bottom surface, and the disk has a matching block with a corresponding inclined upper surface to push the limiting block.
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 is currently in force. Making or selling this specific configuration in China would require the owner’s permission. It has no US or other foreign counterpart.
Two points to settle early:
- Other patents may exist. Manual pencil sharpeners are a mature field with many existing patents covering cam mechanisms, blade angles, and holder geometries. A freedom-to-operate (FTO) review is recommended to ensure your implementation of the rotary disk synchronization does not infringe on older US or international patents in the office supplies sector.
- Material safety. Since this is a school and office product, materials must comply with strict chemical restrictions.
Customization and manufacturing
What can be customized
| Area | Options |
|---|---|
| Disk profile | Cam shapes for different height ranges and tilt angles |
| Blocking members | Number and geometry of staggered supports for specific pencil sizes |
| Materials | Metal vs. reinforced polymer for the disk and rest |
| Elastic element | Spring type and tension for hob contact pressure |
| Finish | Paint, plating, or raw material color |
Things to plan for (US market)
- ASTM F963 - Standard Consumer Safety Specification for Toy Safety. While sharpeners are not always toys, if marketed to children under 12, this applies.
- CPSIA Lead & Phthalates - Surface coatings and substrates must meet limits for children’s products.
- California Prop 65 - Screening for heavy metals and phthalates in plastics and finishes.
- Small Parts Regulations - If detachable parts like the disk or blockers are small enough to pose a choking hazard, warnings or design changes are needed.
How a project runs
- Inquiry - Define target pencil types, desired tip tapers, and quantity.
- Design - CAD modeling of the cam surfaces, gear ratios, and elastic spring rates.
- Prototype - 3D printed or CNC machined units to test synchronization smoothness and cutting consistency.
- Pilot run - Tooling creation, injection molding trials, and safety testing.
- Production - Mass manufacturing, assembly, and QC checks.
Quantities & timeline
The rotary disk and clamping pieces require precision molds to maintain the irregular cam profiles. Gear teeth must mesh accurately to prevent binding. Testing cycles for tip consistency across pencil hardness levels take time. Send us your target pencil specifications, material preferences, estimated quantity and we will reply with options.
Patent drawings
Drawings reproduced from the public patent document for reference.
