Tool driving or impacting – Drive controlled by relative axial movement of tool – Drive motor controlled
Reexamination Certificate
1999-05-18
2001-02-27
Smith, Scott A. (Department: 3721)
Tool driving or impacting
Drive controlled by relative axial movement of tool
Drive motor controlled
C173S122000, C173S128000, C173S205000
Reexamination Certificate
active
06192995
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rotary impacting apparatus capable of providing high-frequency impacting force.
2. Description of the Related Art
Generally, an impacting apparatus such as a concrete breaker utilizes expansive force of compressed air or a combination of a motor and a crank mechanism for reciprocating an impacting piston in the main body. When reciprocated, the impacting piston repetitively hits a reciprocating implement supported at an end portion of the main body in an axial direction.
In the impacting apparatus of the above type, the impacting piston is forcibly reciprocated, so that the main body of the impacting apparatus will unfavorably be vibrated due to reaction from the impacting piston in motion. In addition, it is difficult to increase the frequency of reciprocation of the impacting piston due to the inertial mass of the impacting piston.
In order to overcome the above problems, the applicant of the present application proposed a rotary impacting apparatus as disclosed in U.S. Pat. No. 5,488,997. This rotary impacting apparatus includes a rotor which is rotatably supported by a housing, and a main reciprocative implement which is reciprocatively held by the housing. The rotor loosely retains an impact member. While the rotor is being rotated, the impact member repeatedly hits an impact receiving face of the main reciprocative implement, thereby causing the main reciprocative implement to reciprocate in a predetermined direction.
In the above rotary impacting apparatus, however, use is made of ball bearings for supporting the rotor within the housing. It has been found that the ball bearings, in repeated use, will often lose their initial function due to breakage of the ball retainers of the ball bearings for example. In such an unfavorable instance, the rotor may become unable to rotate smoothly or even unable to rotate at all.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention is to provide a rotary impacting apparatus which overcomes the above-described problems.
According to the present invention, there is provided a rotary impacting apparatus comprising:
a housing;
a rotor rotatably accommodated in the housing;
a driving source for rotating the rotor about a rotation axis;
a main reciprocative implement reciprocatively held by the housing; and
an impact member eccentrically held by the rotor, the impact member exerting an impacting force for pressing the main reciprocative implement when the main receprocative implement is advanced relative to the rotation axis;
characterised in that the rotor is supported by the housing via needle bearings.
With such an arrangement, the rotor is properly rotated since use is made of needle bearings for supporting the rotor instead of ball bearings.
According to a preferred embodiment, the main reciprocative implement is provided with an impact receiving face at which the impact member hits the main reciprocative implement, wherein the impact receiving face is arranged in parallel to the rotation axis.
The main reciprocative implement may comprise a shovel. Alternatively, the shovel may be replaced with a chisel.
Preferably, the impact member may have a columnar configuration.
The rotor may be formed with retaining holes for loosely retaining the impact member.
Preferably, a center of gravity of an assembly including the rotor and the impact member substantially coincides with the rotation axis when the rotor is rotating while the impact member is being held out of engagement with the main reciprocative implement.
When the main reciprocative implement comprises a shovel, it is preferable that the rotary impacting apparatus further comprises an auxiliary reciprocating member reciprocatively held by the housing for transmitting an impacting force from the impact member to the main reciprocative implement when the main reciprocative implement is advanced relative to the rotation axis by a predetermined distance.
The auxiliary reciprocating member may be rotatably held by the housing, whereas the main reciprocative implement may be nonrotatably held by the housing.
In the preferred embodiment, the rotor comprises a pair of flanges, a connector for connecting the flanges, and shafts projecting oppositely from the flanges, wherein the shafts are supported by the housing via the needle bearings.
Other objects, features and advantages of the present invention will become clearer from the detailed description of the preferred embodiment given below with reference to the accompanying drawings.
REFERENCES:
patent: 3108644 (1963-10-01), Gustafson
patent: 3642077 (1972-02-01), Bayard
patent: 4014392 (1977-03-01), Ross
patent: 4601350 (1986-07-01), Mikiya
patent: 5117923 (1992-06-01), Wuhrer
patent: 5488997 (1996-02-01), Yamada
Bednarek Michael D.
Shaw Pittman
Smith Scott A.
Yamada Machinery Industrial Co., Ltd.
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