Gear made of resin, and mold structure

• US 6,883,397 B2
• Filed: 07/05/2001
• Issued: 04/26/2005
• Est. Priority Date: 07/06/2000
• Status: Expired due to Fees

• Current Assignee: Enplas Corporation
• Original Assignee: Enplas Corporation
• Inventors: Kimizuka, Genichi
• Primary Examiner(s): Bucci, David A.
• Assistant Examiner(s): Van Pelt, Bradley J.
• Application Number:
  US09/899,608
• Publication Number:
  US 20020014133A1
• Time in Patent Office: 1,391 Days
• Field of Search: 744/37, 744/60, 744/61, 744/62, 74D/IG.10, 744/68, 744/67, 744/43, 744/45, 474/149, 474/152, 474/153, 474/161, 474/156, 474/202
• US Class Current: 74/462
• CPC Class Codes: B29C 33/20 Opening, closing or clamping
• CPC Class Codes: B29C 33/44 with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles
• CPC Class Codes: B29D 15/00 Producing gear wheels or similar articles with grooves or projections, e.g. control knobs
• CPC Class Codes: B29L 2015/003 Gears
• CPC Class Codes: F16H 2055/065 Moulded gears, e.g. inserts therefor
• CPC Class Codes: F16H 55/06 Use of materials; Use of treatments of toothed members or worms to affect their intrinsic material properties coatings for lubrication F16H57/041; producing gear wheels from plastics or substances in a plastic state B29D15/00; heat treatment C21D9/32; electrolytic surface treatment C25D; heating by electromagnetic field H05B6/00
• CPC Class Codes: F16H 55/17 Toothed wheels worm wheels F16H55/22; chain wheels F16H55/30
• CPC Class Codes: F16H 57/04 Features relating to lubrication or cooling or heatingin hydrokinetic gearing F16H41/30; control of lubrication or cooling in hydrostatic gearing F16H61/4165
• CPC Class Codes: Y10S 74/10 Polymer digest - plastic gears
• CPC Class Codes: Y10T 74/19963 Spur
• CPC Class Codes: Y10T 74/19972 form
• CPC Class Codes: Y10T 74/19995 Teeth

Abstract

A gear made of a resin includes a substantially cylindrical rim having a plurality of teeth formed around an outer periphery thereof, a boss formed about a rotational center of the rim, and a web connecting the boss and the rim to each other. At least one groove is defined along outer surface of each tooth to divide the tooth in a widthwise direction of the tooth. As a result, a portion of the gear, in which the grooves are defined, is deformed in a reduced amount, leading to a reduced amount of deformation such as a warpage or sink in the entire gear, thereby providing an enhancement in tooth flank accuracy. Since the grooves are defined along the outer surfaces of the teeth, a lubricant such as grease can be supplied effectively to tooth flanks by previously applying the lubricant in the grooves.

Claims

1. A single gear made of resin, comprising a substantially cylindrical rim having a plurality of teeth formed around an outer periphery thereof with each of said plurality of teeth having front and rear facing surfaces and a top, a boss formed about a rotational center of said rim, and a web connecting said boss and said rim to each other, wherein

at least one groove is defined along an entire outer peripheral surface of each tooth of said teeth, said at least one groove being provided in said outer peripheral surface of each of said front and rear facing surfaces and said top of each of said plurality of teeth and in a valley provided between each successive ones of said plurality of teeth, said at least one groove defining at least a central gear portion and at least two outer gear portions wherein said central gear portion comprises central gear teeth smaller than outer gear teeth of said two outer gear portions.

2. The single gear of claim 1, wherein the groove is formed at substantially the center in the widthwise direction of the teeth.

3. The single gear of claim 1, wherein a plurality of said groves are provided along the outer surface of the teeth.