JPS64289Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an impact wrench used for tightening bolts, nuts, etc., and particularly to a lubricating device for the hammer and the outer periphery of the anvil.

A rotatable cylindrical hammer frame, a hammer with a generally arcuate cross section that is swingably disposed on the inner periphery of the hammer frame, and an anvil that is relatively rotatably disposed at the rotation axis of the hammer frame. and a cam surface for swinging the hammer is formed on the outer circumferential surface of the anvil to rotate the hammer around the rotational axis and apply a rotational impact force to the anvil. In impact wrenches, conventional methods of lubrication between the hammer and the outer periphery of the anvil include those filled with lubricant such as grease and those filled with oil, but in the former case, the lubricant scatters during the striking action and is not necessary. In the latter case, the structure became complicated and resistance increased, and it was difficult to maintain function due to oil leakage.

In view of these conventional problems, it is an object of the present invention to provide a lubricating device for an impact wrench that is filled with a lubricant such as grease and can sufficiently lubricate the striking part.

Therefore, in the present invention, the inner circumferential surface of the hammer frame is formed such that the hammer arrangement position has a large diameter with respect to the rotation axis, and the opposite side in the diametrical direction has a small diameter. The centrifugal force acting on the lubricant due to the rotation of the lubricant moves the lubricant to the position of the hammer, and the lubricant is collected at the position of the hammer by forming a lubricant passage hole passing through the hammer in the radial direction. To provide a lubricating device in which the lubricant is pushed out to the inner surface of the hammer through a lubricant passage hole by swinging of the hammer, and the lubricant is scattered during a striking operation so that the lubricant is attached to a necessary striking part.

An embodiment of the present invention will be described below based on the drawings. In FIG. 1, reference numeral 1 denotes an impact wrench main body, and a cam disc 4 is fitted onto the front end of a rotor shaft 3 of an air motor 2 provided in the rear part of the main body. 5 is
It is a cylindrical hammer frame, and a flange portion 5a on the inner periphery of the rear end fits into the boss portion 4a of the cam disk 4. Reference numeral 6 denotes an anvil disposed at the axial center position of the hammer frame 5, and is supported by the bearing 7 at the front end of the casing of the impact wrench body 1 and the front end of the center hole of the cam disc 4, and the supporting shaft portions 6a on both sides thereof. 6b are rotatably supported, and the front end of this anvil 6 is formed with a square shaft portion 6c into which a socket body (not shown) is fitted into the head of a nut or bolt. Reference numeral 8 denotes a front support plate which is rotatably fitted into the large diameter part 6d between the main body part and the front support shaft part 6a of the anvil 6, and the hammer frame 5 is attached to the outer periphery of the front support plate.
The front end portions of the hammer frame 5 are fitted together, and the hammer frame 5 is rotatably supported concentrically with the anvil 6 by the flange portion 5a and the front support plate 8. 10 is a hammer, as shown in FIGS. 1 and 2, a groove 9a having an arcuate cross section on the inner peripheral surface of the hammer frame 5 and a flange portion 5.
A round shaft-shaped support part 1 that fits into the hole 9b of a, a striking part 12 extending inwardly from this supporting part 11 in an arched manner, and a support at the rear of this striking part 12. The engagement part 13 for power transmission is formed slightly radially inward from the part 11, and is held on the inner peripheral part of the hammer frame 5 so as to be swingable by the support part 11. The engaging portion 13 is fitted into a U-shaped recess 14 formed in the cam disk 4, and the width of the recess 14 is equal to the width of the engaging portion 1.
The width of the engaging part 13 is wider than the width of the recess 1.
4, and is configured to allow slight relative movement between both sides thereof. The inner circumferential surface of the hammer frame 5 is defined as r, where _r1 is the radius from the center of rotation O of the hammer frame 5 at the placement position of the hammer 10, and _r2 is the radius at a position diametrically opposite to the placement position of the hammer 10. It is eccentrically formed so that ₁ > r ₂ . On the outer peripheral surface of the anvil 6, a protrusion 1 is provided in the middle.
5, the striking portion 12 of the hammer 10 collides with the anvil 6 and applies a rotational impact force to the anvil 6.
6 are formed as a pair, and between these abutting surfaces 16, the hammer 10 is moved between a position where the striking part 12 located forward in the rotational direction of the hammer 10 projects inward and a position along the inner circumferential surface of the hammer frame 5. A cam surface 17 for rocking is formed. A concave part 18 is formed at the base of the striking part 12 of the hammer 10, that is, on the outer surface of the connection part with the support part 11, and this concave part 1
A lubricant passage hole 19 is formed radially through the connecting portion 8 toward the inner surface of the connecting portion. 20 is an operating lever of the impact wrench body 1, and 21 is a lubricant such as grease sealed in the hammer frame 5.

In the above configuration, the impact wrench body 1
When the operating lever 20 is pressed, the cam disk 4 rotates via the rotor shaft 3 of the air motor 2, and the recess 1
4 and the engagement portion 13 of the hammer 10, the hammer 10 rotates together with the hammer frame 5, and the engagement between the striking portion 12 of the hammer 10 and the abutment surface 16 of the anvil 6 rotates the anvil 6, causing the hammer 10 to rotate together with the hammer frame 5. The socket body fitted on the square shaft portion 6c at the front end is rotated to thread a screw such as a bolt or nut. When the screw tightening progresses and the resistance from the anvil 6 side exceeds a certain value and the rotation of the anvil 6 approaches a stop, the cam circle becomes smaller than the locking force between the abutment surface 16 and the striking part 12 of the hammer 10. The swinging moment of the hammer 10 due to the engagement part 13 of the hammer 10 being pushed by the plate 4 increases, the striking part 12 slides outward from the abutting surface 16, the hammer 10 comes off the anvil 6, and the cam Free running is performed integrally with the disc 4. When the hammer 10 free-runs for nearly one rotation, as shown in FIG. abutment surface 1
6, the striking portion 12 and the abutment surface 16 collide with each other, and a rotational impact force is applied to the anvil 6. When the collision occurs, the hammer 10 and hammer frame 5 first rotate in the opposite direction as shown in Fig. 3 due to the reaction, and then start rotating forward due to the driving force of the air motor 2. At this time, since the rotation speed of the hammer 10 is slow, the hammer 10 and the hammer frame 5 rotate in the forward direction. Before the striking part 12 and the abutting surface 16 engage, the engaging part 13 is pushed by the cam disk 4, so that the striking part 12 at the front in the rotational direction is displaced outward, and the abutting surface 16 and the engaging part 13 are pushed. Free running as shown in FIGS. 4 and 5 without engaging, and thereafter the hammer 10 is pressed in the same manner.
The striking portion 12 of the anvil 6 repeatedly collides with the abutting surface 16 of the anvil 6, and the screw is completely fastened by the impact rotational force.

During such a fastening operation, the lubricant 21 sealed in the hammer frame 5 is scattered in four directions due to the collision as shown in FIG. As the lubricant 21 rotates at high speed, the lubricant 21 moves along the inner peripheral surface of the hammer frame 5 due to centrifugal force, as shown in FIGS. They will gather at 10 locations. Thereafter, as shown in FIG. 5, the striking part 12 on the rear side in the rotation direction of the hammer 10 passes through the small diameter part of the cam surface 17 of the anvil 6, so that the striking part 12 on the front side in the rotation direction is displaced outward. This striking part 12
A lubricant 21 is placed between the inner peripheral surface of the hammer frame 5 and
is pushed out from the concave portion 18 through the lubricant passage hole 19 to the inner surface of the hammer 10, and from this state, as shown in FIG.
is displaced inward, and the striking portion 12 collides with the abutting surface 16 of the anvil 6, and the impact causes the lubricant 21 attached to the inner surface of the hammer 10 to scatter and adhere to various parts. , especially the abutment surface 1 of the anvil 6
By adhering a large amount to 6, the necessary lubrication of the striking part is sufficiently performed. In addition, by making the diameter of the portion of the inner peripheral surface of the hammer frame 5 on the opposite side in the diametrical direction from the hammer 10 placement position smaller, the hammer frame 5
has a thick wall in this part, and therefore this part also functions as a weight balance part for the hammer 10.

According to the impact wrench lubrication device of the present invention, as is clear from the above description, the inner peripheral surface of the hammer frame is formed such that the diameter is large at the position where the hammer is arranged and the diameter is small at the opposite side in the diametrical direction. Because there are
As the hammer frame rotates, lubricant can be collected at the hammer placement position by centrifugal force, and since the hammer is provided with a lubricant passage hole that penetrates in the radial direction, the hammer is oscillated by the cam surface of the anvil. By moving the hammer, the lubricant that has collected at the location of the hammer can be pushed out to the inner surface of the hammer through the lubricant passage hole, and this lubricant is scattered during the striking action, causing the abutment surface of the anvil to be pushed out. The lubricant adheres to the necessary striking parts, providing sufficient lubrication.Moreover, the structure is extremely simple, and the hammer frame has a thick wall at the small diameter part of its circumference, making it possible to achieve this effect. This part also functions as a balance weight part for the hammer, and there is no need to provide a separate balance weight for the hammer, resulting in many effects.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a front view of the main part in cross section, and FIGS.
It is an explanatory diagram of operation taken along the line AA in the figure. 4...Cam disk, 5...Hammer frame, 6...Anvil, 10...Hammer, 11...Support, 1
2... striking part, 13... engaging part, 14... recessed part,
16...Abutment surface, 17...Cam surface, 19...Lubricant passage hole, 21...Lubricant.

Claims (1)

[Scope of utility model registration request] A hammer having a generally arcuate cross section is swingably disposed on the inner periphery of a rotatable cylindrical hammer frame, and
An anvil having an outer peripheral surface formed with a surface that abuts the hammer and a cam surface that swings the hammer is disposed so as to be able to rotate relative to the rotational axis of the hammer frame, and the hammer is rotated about the rotational axis. In the impact wrench, the inner peripheral surface of the hammer frame has a large diameter relative to the rotational axis at the position where the hammer is arranged, and a small diameter on the opposite side in the diametrical direction. 1. A lubricating device for an impact wrench, characterized in that the hammer has a lubricant passage hole that penetrates the hammer in a radial direction.