Machining of gear workpieces
Gears in engineering are widely used to transfer rotational motion from one machine shaft to another in one or different planes. They are divided into: cylindrical, conical, rack (Figure 11.94), as well as worm.
Fig. 11.94. Examples of toothed parts
Cylindrical: a - straight-toothed outer; b - helical teeth; в - internal; r is the shaft; d - conical with curved teeth; e is the rake
Depending on the design of the teeth, each type of gear is assigned to one or another group. Distinguish cylindrical wheels - spur, external, internal, helical, chevron, and conical - spur, helical and with curved teeth (for example, hypoid). In addition to wheels with toothed gearing, shafts, slats, worm shafts, etc. are made.
Methods of manufacturing gears (wheels, gears, slats, etc.) are very diverse and include the shaping of the tooth with worm cutters on gear-cutting machines; dolbyakami and combs on gears; cutters on gear-cutting machines.
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Processing of blanks on gear-cutting machines
In the production of gears, the cutting of teeth on gear-milling machines with worm cutters is the most common. This method can be used to cut cylindrical gears of external engagement with straight and oblique teeth of standard, conical and barrel-shaped, block and worm gears, splined shafts, sprockets of chain gears, etc.
Shaping during tooth-cutting with worm cutters (Figure 11.95) occurs as a result of the movement of the envelopes of the successive positions of the cutting edges of the cutter with two coordinated feed movements: a constructive translational and working rotational tangential to the trail of the working forward or screw feed motion and rotational cutting motion of the cutting point edges.
Fig. 11.95. An example of cutting a gear with a worm cutter
Often, for the conditions of a single production, the methods of cutting teeth with modular cutters are used (Figure 11.96) on milling machines equipped with dividing heads. Modular cutters are divided into disk and finger. Examples of gear hobbing machines are shown in Fig. 11.97.
Fig. 11.96. Schemes for cutting gears with modular cutters:
a - disk; 6 - Fingerprint
Fig. 11.97. Gear Hobbing Machines
Processing of blanks on gear-cutting machines. On gear-cutting machines, the teeth are cut by turning round round blades and jagged combs and copying with multi-head heads. The cutting of the outer and inner teeth with round blades (Figure 11.98) is the main and most common method of obtaining gears of high quality.
Fig. 11.98. The appearance of the dolbyakov:
а - насадные; b is the tail
The method is based on the reproduction of a gear pair pair of gears. The cutting of the teeth is performed by the planter with the reciprocating motion along the vertical axis of the workpiece (Fig. 11.99). The chips are removed during the working stroke of the dolbyak down the entire width of the tooth. At the reverse stroke, the tool is removed from the workpiece (or vice versa). In the process of cutting, the wheel and the bucket rotate continuously and consistently, making the rolling movement to give the involute profile to the teeth.
Fig. 11.99. Scheme of gear cutting with a dolbyak:
a - external cutting; b - internal cutting; V x , V p - speed of idle and working stroke; V з , V д - speed of rotation, respectively, the workpiece and dolbyaka; S is the insertion direction
Toothed combs 1 (Figure 11.100) are mainly used for cutting large-grain wheels 2. Examples of gear-cutting machines are shown in Fig. 11.101.
Fig. 11.100. Scheme for cutting teeth with combs
Fig. 11.101. Gear Shapers
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