US2013259694A1PendingUtilityA1
Method for Manufacturing Multi-Finger Pinned Root for Turbine Blade Attached to Turbine Rotor and Turbine Blade
Est. expiryMar 30, 2032(~5.7 yrs left)· nominal 20-yr term from priority
Y10T29/49316F05D 2230/10F01D 5/3023F01D 5/3053B23D 75/00
43
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Claims
Abstract
In manufacturing a multi-finger pinned root pin-coupling a turbine blade made of a high-strength material and a rotor disc, a reamer used to ream a pin insertion hole formed through a turbine blade attachment base is removed from the pin insertion hole while being rotated so as to cause a scratch formed by a chip on the inner surface of the pin insertion hole to be inclined with respect to the axial direction of the pin insertion hole. This brings the direction of the scratch on the inner surface of the pin insertion hole and the direction of tensile stress generated on the inner surface of the pin insertion hole adequately close to be parallel to each other. As a result, the fatigue strength reduction caused by the scratch can be inhibited.
Claims
exact text as granted — not AI-modified1 . A method for manufacturing a multi-finger pinned root for turbine blade attached to a turbine rotor, the multi-finger pinned root coupling a turbine blade and a rotor disc of the turbine rotor, wherein a pin insertion hole is formed through a turbine blade attachment base through steps of:
drilling a through-hole; reaming the drilled through-hole using a reamer; and removing the reamer from the reamed through-hole while rotating the reamer after the reaming.
2 . The method for manufacturing a multi-finger pinned root for turbine blade attached to a turbine rotor according to claim 1 , wherein the reamer is removed at a reamer rotation speed f (rpm) and a reamer removal speed v (mm/min) both determined to satisfy the following expression (1):
Kt
≥
1
+
4
a
h
1
1
+
(
2
π
r
·
f
v
)
2
(
1
)
where a/h is an aspect ratio (a=depth, h=width) of a scratch formed when the reamer is removed, Kt is an allowable stress concentration factor, and r is a radius (mm) of the reamer.
3 . The method for manufacturing a multi-finger pinned root for turbine blade attached to a turbine rotor according to claim 2 , wherein, with 0.1 assigned to a/h and 1.2 assigned to Kt in the expression (1), the reamer is removed at a reamer rotation speed f (rpm) and a reamer removal speed v (mm/min) both determined to satisfy the following expression (2):
1.2
≥
1
+
0.4
1
1
+
(
2
π
r
·
f
v
)
2
(
2
)
4 . The method for manufacturing a multi-finger pinned root for turbine blade attached to a turbine rotor according to claim 1 , wherein, after the reamer is removed from the pin insertion hole, an inner surface of the pin insertion hole is observed to determine that an angle θ formed between a scratch formed on the inner surface of the pin insertion hole and an axial direction of the pin insertion hole is not smaller than a predetermined angle.
5 . The method for manufacturing a multi-finger pinned root for turbine blade attached to a turbine rotor according to claim 2 , wherein, after the reamer is removed from the pin insertion hole, an inner surface of the pin insertion hole is observed to determine whether an angle θ formed between a scratch formed on the inner surface of the pin insertion hole and an axial direction of the pin insertion hole satisfies the following expression (3):
θ
≥
cos
-
1
{
(
Kt
-
1
)
h
4
a
}
(
3
)
6 . The method for manufacturing a multi-finger pinned root for turbine blade attached to a turbine rotor according claim 4 , wherein the inner surface of the pin insertion hole is observed using a microscope.
7 . The method for manufacturing a multi-finger pinned root for turbine blade attached to a turbine rotor according claim 5 , wherein the inner surface of the pin insertion hole is observed using a microscope.
8 . The method for manufacturing a multi-finger pinned root for turbine blade attached to a turbine rotor according claim 4 , wherein, of the inner surface of the pin insertion hole, only a predetermined area repeatedly subjected to a large tensile load while the turbine is rotating is observed.
9 . The method for manufacturing a multi-finger pinned root for turbine blade attached to a turbine rotor according claim 5 , wherein, of the inner surface of the pin insertion hole, only a predetermined area repeatedly subjected to a large tensile load while the turbine is rotating is observed.
10 . The method for manufacturing a multi-finger pinned root for turbine blade attached to a turbine rotor according to claim 8 , wherein the area to be observed ranges from 50° to 130° with respect to 0° corresponding to a bottom toward the axis of the turbine rotor of the inner surface of the pin insertion hole.
11 . The method for manufacturing a multi-finger pinned root for turbine blade attached to a turbine rotor according to claim 9 , wherein the area to be observed ranges from 50° to 130° with respect to 0° corresponding to a bottom toward the axis of the turbine rotor of the inner surface of the pin insertion hole.
12 . A turbine blade to be pin-coupled to a rotor disc of a turbine rotor, wherein a scratch formed on an inner surface of a pin insertion hole formed through the turbine blade is inclined with respect to an axial direction of the pin insertion hole.
13 . The turbine blade according to claim 12 , wherein an angle θ formed between the scratch and the axial direction of the pin insertion hole satisfies the following expression (4):
θ
≥
cos
-
1
{
(
Kt
-
1
)
h
4
a
}
(
4
)
where a/h is an aspect ratio (a=depth, h=width) of the scratch formed on the inner surface of the pin insertion hole and Kt is an allowable stress concentration factor.
14 . The turbine blade according to claim 13 , wherein, with the aspect ratio a/h of the scratch being 0.1 and the allowable stress concentration factor Kt being 1.2, the angle θ formed between the scratch and the axial direction of the pin insertion hole is 60° or greater.
15 . A turbine blade for use in a last stage of a low-pressure turbine, the turbine blade being made of a high-strength material and having a blade fork portion to be pin-coupled with a rotor fork formed on a rotor disc of a turbine rotor, wherein a scratch formed on an inner surface of a pin insertion hole formed through the blade fork portion is inclined with respect to an axial direction of the pin insertion hole.Join the waitlist — get patent alerts
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