Injection-molded resin face gear

Abstract

An injection-molded resin face gear that can suppress deterioration of gear accuracy caused by shrinkage of resin material after injection molding and allow accurate and smooth rotation transmission is provided. An injection-molded resin face gear 1 includes a boss 3, a disk-shaped web 4, and a teeth section 5. The boss 3 has an axis hole 2. The web 4 is formed on an outer circumferential side of the boss in an outward radial direction. The teeth section 5 is formed on an outer circumferential edge of the web 4. The teeth section 5 includes a cylindrical section 13, a disk-shaped section 14, and a plurality of teeth 15. The cylindrical section 13 is connected to the outer circumferential edge of the web 4. The disk-shaped section 14 is formed on one end side of the cylindrical section 13 in the outward radial direction. The teeth 15 are formed evenly spaced on an outer circumferential side of the cylindrical section 13 such that one side surface of the disk-shaped section 14 is a bottom land 16. The web 4, the cylindrical section 13, and the disk-shaped section 14 have almost the same thicknesses. The outer circumferential edge of the web 4 is connected between an end surface 19 and an end surface 22 of the cylindrical section 13, in almost the center in a direction along a rotational center axis CL.

What is claimed is: 
     
       1. An injection-molded resin face gear including a boss, a disk-shaped web formed on an outer circumferential side of the boss in an outward radial direction, and a teeth section formed on an outer peripheral edge of the web, wherein:
 the teeth section includes a cylindrical section connected to the outer peripheral edge of the web, a disk-shaped section formed on one end side of the cylindrical section in the outward radial direction, and a plurality of teeth formed evenly spaced on an outer circumferential side of the cylindrical section such that one side surface of the disk-shaped section is a bottom land; 
 the web,a thickness of the cylindrical section, and a thickness of the disk-shaped section have same thicknesses a lower threshold of 0.7 t1 and an upper threshold of 1.3 t1 where t1 is a thickness of the web; and 
 an entire connection section between the web and the cylindrical section is positioned between an end surface on the one end side of the cylindrical section and an end surface on another end side that is an opposite side to the one end side, and is positioned such as to be misaligned with another side surface of the disk-shaped section and an end surface on the other end side of the cylindrical section, along a direction in which a rotational center axis extends. 
 
     
     
       2. An injection-molded resin face gear including a boss, a disk-shaped web formed on an outer circumferential side of the boss in an outward radial direction, and a teeth section formed on an outer peripheral edge of the web, wherein:
 the teeth section includes a cylindrical section connected to the outer peripheral edge of the web, a disk-shaped section formed on one end side of the cylindrical section in the outward radial direction, and a plurality of teeth formed evenly spaced on an outer circumferential side of the cylindrical section such that one side surface of the disk-shaped section is a bottom land; 
 the web,a thickness of the cylindrical section, and a thickness of the disk-shaped section have same thicknesses a lower threshold of 0.7 t1 and an upper threshold of 1.3 t1 where t1 is a thickness of the web; 
 an entire connection section between the web and the cylindrical section is positioned between an end surface on the one end side of the cylindrical section and an end surface on another end side that is an opposite side to the one end side, and is positioned such as to be misaligned with another side surface of the disk-shaped section and an end surface on the other end side of the cylindrical section, along a direction in which a rotational center axis extends; 
 another side surface of the disk-shaped section and the end surface on the one end side of the cylindrical section are positioned on a same plane, an outer peripheral surface of the disk-shaped section and an outer peripheral surface of the teeth are positioned on a same peripheral surface, tooth crests of the teeth and the end surface on the other end side of the cylindrical section are positioned on a same plane; 
 when a thickness of the web is t 1 , a length from the end surface on the one end side of the cylindrical section to the end surface on the other end side along the direction in which the rotational center axis extends is 3·t 1 ; 
 a length from the connection section between the web and the cylindrical section to the end surface on the one end side of the cylindrical section along the direction in which the rotational center axis extends is t 1 ; and 
 a length from the connection section between the web and the cylindrical section to the end surface on the other end side of the cylindrical section along the direction in which the rotational center axis extends is t 1 .