Impact tool, spindle, and spindle manufacturing method
An impact tool includes: a motor; a sun gear rotated by the motor; and at least three planet gears, which mesh with the sun gear; an internal gear, which meshes with the planet gears. A spindle includes a flange portion having a hole in an axial direction for the insertion of the sun gear, and slit portions in at least a side surface thereof for mounting the planet gears, and a shaft portion extending forward from the flange portion in the axial direction. The flange portion is shaped by forging. A hammer is held on the spindle; an anvil is impacted by the hammer in a rotational direction. A hammer case houses the hammer and holds the anvil in a rotatable manner; a tool-accessory retaining part is formed on the anvil; and a coil spring biases the hammer toward the anvil.
1 . An impact tool comprising:
a motor;
a sun gear rotated by the motor;
at least three planet gears, which mesh with the sun gear;
an internal gear, which meshes with the planet gears;
a spindle, which includes a flange portion—having a hole in an axial direction in which the sun gear is inserted, and slit portions in at least a side surface thereof in which the planet gears are mounted—and a shaft portion extending forward from the flange portion in the axial direction, at least a portion of the flange portion having been shaped by forging;
a hammer, which is held on the spindle;
an anvil configured to be impacted by the hammer in a rotational direction;
a hammer case, which houses the hammer and holds the anvil in a rotatable manner;
a tool-accessory retaining part, which is provided on the anvil; and
a coil spring, which biases the hammer toward the anvil;
wherein grain flows in the flange portion of the spindle are formed by the forging to extend outward from the center of the radial direction.
2 . The impact tool according to claim 1 , wherein the flange portion has a cut surface on at least a portion of a surface.
3 . The impact tool according to claim 1 , further comprising:
a ball disposed between the spindle and the hammer;
wherein the spindle has, in the shaft portion, a spindle groove in which at least a portion of the ball is disposed.
4 . The impact tool according to claim 1 , wherein the spindle is formed using a steel that contains 0.13-1.00 mass % carbon and at least 0.90 mass % chromium.
5 . The impact tool according to claim 1 , wherein the spindle has:
a first flange connected to the shaft portion;
a second flange disposed opposing the first flange and rearward of the first flange; and
at least one coupling portion, which connects the first flange and the second flange to each other in the axial direction.
6 . The impact tool according to claim 5 , wherein:
a plurality of the coupling portions is arranged in the circumferential direction and connects the first flange and the second flange to each other in the axial direction; and
each of the planet gears is disposed respectively between mutually adjacent coupling portions at a location sandwiched between the first flange and the second flange.
7 . The impact tool according to claim 5 , wherein portions of the spindle that face openings surrounded by the first flange, the second flange, and the plurality of coupling portions are non-cut portions.
8 . A spindle used in a power tool, comprising:
a flange portion having a hole in an axial direction for the insertion of a sun gear, and slit portions in at least a side surface thereof for mounting planet gears; and
a shaft portion extending forward from the flange portion;
wherein the flange portion has been shaped by forging.
9 . The spindle according to claim 8 , wherein the flange portion has a cut surface on at least a portion of a surface.
10 . The spindle according to claim 8 , wherein the shaft portion has a spindle groove in which at least a portion of a ball is disposed.
11 . The spindle according to claim 8 , wherein the spindle is formed using a steel that contains 0.13-1.00 mass % carbon and at least 0.90 mass % chromium.
12 . The spindle according to claim 8 , wherein grain flows in the flange portion are formed by the forging to extend outward from the center of the radial direction.
13 . The spindle according to claim 8 , wherein the flange portion has:
a first flange connected to the shaft portion;
a second flange disposed opposing the first flange and rearward of the first flange; and
a coupling portion, which couples the first flange and the second flange to each other in the axial direction.
14 . The spindle according to claim 13 , wherein:
a plurality of the coupling portions is disposed in a circumferential direction; and
each of the planet gears is disposed respectively between mutually adjacent coupling portions at a location sandwiched between the first flange and the second flange.
15 . The spindle according to claim 13 , wherein portion of the flange that face openings surrounded by the first flange, the second flange, and the plurality of coupling portions are non-cut portions.
16 . A method of manufacturing a spindle comprising a flange portion—having a hole in an axial direction for the insertion of a sun gear, and a slit portion in at least a side surface thereof for mounting a planet gear—and a shaft portion extending forward from the flange portion, the spindle being used in a power tool, the manufacturing method comprising:
providing a slug, which has a flange-corresponding portion and a shaft-corresponding portion that correspond to the flange portion and the shaft portion, respectively;
disposing, with respect to the flange-corresponding portion of the slug, a die in which a slit-corresponding part, which corresponds to the slit portion, is formed; and
forming the slit portion by forging, in which, in the state in which the die is disposed, a rear-end portion of the flange-corresponding portion is struck in the axial direction to cause plastic deformation of the flange-corresponding portion along the slit-corresponding part of the die.
17 . The method according to claim 16 , further comprising:
forming the hole by cutting the flange-corresponding portion after the plastic deformation of the flange-corresponding portion.
18 . The method according to claim 16 , wherein:
the slug is formed by forging in the state in which the temperature of the material is −20° C. or higher and 40° C. or lower, 300° C. or higher and 850° C. or lower, or 1,000° C. or higher and 1,250° C. or lower; and
the spindle is formed by forging in which the temperature of the formed slug is −20° C. or higher and 40° C. or lower.
19 . The method according to claim 16 , further comprising:
heat treating the spindle after formation by forging until the surface hardness of the spindle becomes 300 HV or more.
20 . The impact tool according to claim 5 , wherein both the first flange and the second flange have been shaped by forging such that grain flows in the first flange and the second flange extend outward from the center of the radial direction.