Основной каталог Kyocera 2021 - 2022 - страница 669

Threading methodsThreading methods TPGB for internal threading

Infeed methods

Infeed methods Features

• The most common threading method. The cutting edge moves toward the center of the workpiece every pass.
• Suitable for relatively small pitch size threading.
• V-shape chips are generated and chip control may be difficult depending on workpiece material.

Radial infeed

• Suitable for large pitch size threading.
• The wear on the right side edge of the figure (no ap) tends to become greater.
• Chips flow to one side.

Flank infeed

• Revised compound methods of the above flank infeed method.
• No “no ap.” condition.
• Chips flow to one side. JJ

3˚~5˚ Flank compound infeed

Lead angle of thread

Thread's lead angle β as shown in fig. 1 decides from the workpiece diameter “D”(Pitch dia.) And the lead “L” (In case of single-start thread, it is the same as pitch “TP”). By rolling a right-angled triangle around a cylinder and the angle ACB in fig. 2 becomes the lead angle β. The calculation formula is shown as follows.

Lead angle L

A

C B

Fig. 1 Fig. 2 Fig. 3

Relief angle of thread Against this lead angle, the threading insert requires side relief angle . Negative type threading insert has no relief angle. When installing the insert in the toolholder, the edge inclination angle (Fig. 3) is set, and at the same time front relief angle as well as side relief angle are generated to the insert. Side relief angle is described by the following formula. (Fig. 4)

= tan ×tan

Table 1

Symbol e.g.)

A Side relief angle α X α: Side relief angle

Inserts

: Inclination angle External insert:10˚ PNA

after installing External Internal

X Fig. 4 Ref. to table 1 for the side relief angle depending on the insert type. However, the side relief angle is set for 1˚ in the traveling direction by the toolholder itself, so that the actual side relief angle becomes +1˚.