MAKING GEARS OR TOOTHED RACKS

**Definition:** This place covers:

Methods and machines specially designed to accurately produce the shapes of gears and other toothed members. Such shapes being essential for proper intermeshing of gearing (and toothed member) elements to ensure the required relative motions. The methods and machines use metal removing processes;

Tools which are specially adapted for use in machines for manufacturing toothed members;

Accessories and equipment for gear making machinery.

**Limiting references (this place does not cover):** - Making gears or toothed racks by stamping -> B21D - Making gears or toothed racks by rolling -> B21H - Making gears or toothed racks by forging or pressing -> B21K - Making gears or toothed racks by casting -> B22D - Making milling cutters by milling per se -> B23C3/36 - Making milling cutters by multi-stage processes -> B23P15/34

**Glossary:** - Gear teeth: In addition to the common meaning of gear teeth, it also covers the teeth or lobes of other accurately intermeshing members having relative movement of a similar kind, such as rotors of rotary pumps and blowers. - Gear cutting: Whilst "cutting" is generally used to refer to material removal using a geometrically defined cutting edge, in this subclass the term "gear cutting" also refers to material removal using geometrically undefined cutting edges, such as by grinding. - Profile: Profile may include the outline of both faces or only one face of a tooth, or the opposing faces of adjacent teeth. - Straight: Straight means that a tooth as a whole (ignoring any curvature of the tooth-face alone, e.g. crowning) is straight in the direction of its length. It accordingly includes the teeth of spur gears, helical gears and normal bevel gears. - Indexing: Indexing in general refers to the process of dividing the periphery of the workpiece into a number of discrete sections. In this subclass the sections are where the teeth are (or will be) formed and indexing refers to the relative angular movement between the workpiece and tool after cutting one tooth in order to allow cutting of the next tooth. - Continuous indexing: Continuous indexing refers to using continuous rotation of the workpiece to enable all teeth to be cut without separation of tool and workpiece for indexing. - Generating: Generating refers to the method of cutting gear teeth using a cutting tool having (or through machine movement, simulating) the shape of a particular gear or rack (dependent on type of gear being produced) and moving the tool relatively to the work piece with a rolling-off motion to cut the tooth profile. - Grinding: Grinding refers to material removal using tools with fixed abrasive particles having geometrically undefined cutting edges. - Planing or Slotting: Planing or slotting refers generally to the removal of material in the form of chips by a relative movement of at least one tool with a geometrically defined cutting edge and the workpiece, along a non-circular trajectory, both tool and workpiece being non-rotating. However in this subclass there may be a relative rotational movement in order to generate tooth profiles. - Skiving: Skiving refers to the removal of material in the form of chips from the workpiece by a toothed tool having geometrically defined cutting edges. The tool and workpiece are both rotated with their rotation axes being at a skewed angle. The tool is fed generally parallel to the workpiece axis. - Milling: Milling refers to the removal of material in the form of chips from a workpiece using a rotating tool with a geometrically defined cutting edge where the main cutting force results from the rotation of the tool. - Hobbing: Hobbing is a milling process where the tool takes the form of a worm in which the threads are gashed to form cutting edges. Both tool and workpiece are rotated. It is a continuous generating process. - Face Milling: Face milling is a milling process where the cutting edges of the tool are on teeth or cutter bars which extend axially from a face of the (usually) circular tool, the face being transverse to the tool rotation axis. - Face Hobbing: Face hobbing is a face milling process using continuous indexing. - Broaching: Broaching refers to the removal of material in the form of chips from a workpiece by a relative movement between a tool having multiple teeth and a workpiece along a non-circular trajectory. The difference in height between successive teeth on a broaching tool determines the feed and hence the chip thickness. - Broach-milling: Broach-milling refers to milling with a rotary cutter having a number of teeth of progressively increasing depth or width - Pot broaching: Pot broaching refers to broaching external teeth with an internally toothed tool. - Honing: Honing generally refers to abrading by means of one or more, often compliant, fine grit abrasive tools along a controlled path of combined movements, including a reciprocating movement, in order to smoothen a surface. In this subclass honing also refers to a surface finishing method using toothed tools where tool and workpiece are in crossed axis meshed engagement. - Lapping: Lapping refers to a surface finishing method using abrasives dispersed in a liquid medium or paste on the engaging surfaces of a workpiece, usually whilst the workpiece is in meshed engagement with another toothed member. - Shaving: Shaving refers to a surface finishing method of material removal in the form of chips using a toothed tool with gashes in the flanks of the teeth that act as the geometrically defined cutting edges, the tool and workpiece are in crossed axis meshed engagement.