Patent Application
20220176512
The present invention relates generally to grinding tools and more particularly, to a portable handheld sander.
A sander is a tool adapted for grinding or cutting workpieces. The portable handheld sander is extensively used in various working places because the handheld sander can be operated by the user with required angle or orientation in grinding the workpiece. However, when the workpiece under grinding has a specific structural profile or the ambient working space is narrow, the conventional handheld sander may not be able to be operated in such a narrow working space because the conventional handheld sander cannot adjust its structure and has a thick body. In other words, the conventional handheld sander needs to be improved.
The present invention has been accomplished in view of the above-noted circumstances. It is an objective of the present invention to provide a handheld sander, whose structure and shape can be adjusted in accordance with various working requirements, such that the handheld sander can extend into a narrow working space for grinding processing.
To attain the above-mentioned objective, the present invention provides a handheld sander comprises a main body, an extension arm, a follower shaft, and a transmission mechanism. The main body includes a housing and a drive shaft rotatably disposed in the housing in a way that the drive shaft is rotatable relative to the housing about a first axis. The extension arm includes a pivot portion rotatably connected with the housing of the main body in a way that the extension arm is rotatable relative to the housing about the first axis, a distal portion opposite to the pivot portion, and an internal accommodation penetrating through the pivot portion and the distal portion. The follower shaft is rotatably disposed in the distal portion in a way that the follower shaft is rotatable about a second axis that is parallel to and spaced from the first axis. The transmission mechanism is disposed in the internal accommodation of the extension arm and connected between the drive shaft and the follower shaft for transmitting a rotational power from the drive shaft to the follower shaft.
As a result, the handheld sander can fulfill different requirements of various working spaces because the extension arm of the handheld sander may have a relatively smaller thickness and can be rotated to various angles in accordance with the user's requirements. Compared to the conventional handheld sander, the handheld sander of the present invention can be operated in a limited, narrow working space to grind workpieces.
The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:
Hereunder an embodiment will be detailedly described with accompanying drawings for illustrating technical features and structure of the present invention. As shown in
Referring to
Referring to
Referring to
The transmission mechanism 50 is disposed in the internal accommodation 36 of the extension arm 30 and connected between the drive shaft 24 and the follower shaft 40 for transmitting a rotational power of the drive shaft 24 to the follower shaft 40. In the present embodiment, the transmission mechanism 50 includes a first gear 52 coaxially connected with the drive shaft 24, a last gear 54 coaxially connected with the follower shaft 40, and two middle gears 56 located between the first gear 52 and the last gear 54 and meshed one with the other in a way that one of the middle gears 56 is meshed with the first gear 52 and the other middle gear 56 is meshed with the last gear 54. In other words, the first gear 52 is indirectly meshed with the last gear 54. The first gear52, the two middle gears 56, and the last gear 54 are all spur gears, thereby reducing transmission loss of the rotational power and enabling that the thickness of the extension arm 30 can be reduced because the spur gears require an installation space of lower height. Further, the transmission shaft 561 of one middle gear 56 is provided with a radial hole 563, into which the second retaining member 70 is optionally inserted. In another feasible embodiment, one or more middle gears 56 can be provided. Alternately, the middle gear 56 can be omitted, such that the first gear 52 is directly meshed with the last gear 54. Moreover, the first gear 52, last gear 54, and the middle gears 56 may be bevel gears, skew gears, etc. That is, they are not limited to spur gears.
In practical operation, when the user presses the switch button 151 on the handlebar 15, as shown in
Since the first positioning member 60 receives a spring force from the first resilient member 225 toward the pivot portion 32, the terminal end of the first retaining member 60 is forced to be inserted into one of the positioning holes 321 to restrict the position of the pivot portion 32. In other words, the extension arm 30 cannot rotate about the first axis A1 relative to the housing 22 at this state. To rotate the extension arm 30, the user can pull outwardly the first retaining member 60 to disengage the terminal end of the first retaining member 60 from the associated positioning hole 321 so as to release the position restriction to the pivot portion 32, and then turn clockwise or counterclockwise the extension arm 30 about the first axis A1 to rotate relative to the housing 22.
To replace the abrasive disc 80, for facilitating dismantlement of the fastening unit 100, the user can push with his/her finger of one hand the second retaining member 70 to force the terminal end of the second retaining member 70 to insert into the radial hole 563 of the transmission shaft 561 of the middle gear 56 to lock the transmission mechanism 50, thereby prohibiting the follower shaft 40 from rotation. As such, the user can use the other hand to dismantle the fastening unit 100 and then replace a new abrasive disc 80.
In the present invention, the extension arm 30 of the handheld sander 10 can be turned to one of various angles in accordance with working requirements. Further, because the thickness of the extension arm 30 is much thinner than that of the main body 20, and the extension arm 30 has a certain length, the extension arm 30 can be extended into a limited, narrow working space for grinding, thereby solving the problem that the conventional handheld sander may not be able to extend into a limited, narrow working space due to the thicker overall thickness of the conventional handheld sander resulted from the design that the abrasive disc of the conventional handheld sander is directly fixed to the drive shaft of the housing. In conclusion, the handheld sander 10 of the present invention is applicable in various working environments, especially in a limited, narrow working space, enhancing the convenience of usage.
Based on the above-mentioned technical features, various modifications to the structure of the handheld sander 10 may be made. For example, the way of restricting the position of the pivot portion 32 to prohibit the pivot portion 32 from rotation is not limited to the way described in the above-mentioned embodiment. As an exemplary embodiment, the pivot portion 32 may be configured as having no such positioning holes 321 on the outer periphery thereof, and the first retaining member 60 is realized as a bolt. By means of abutting the end of the bolt against the outer periphery of the pivot portion 32, the effect of prohibiting the pivot portion 32 from rotation can be achieved too. Alternately, the first retaining member 60 configured in a retractable and extendible manner can be provided at the outer periphery of the pivot portion 32, and the positioning holes 321 are provided at the inner periphery of the sleeve portion 221 for being inserted therein by the first retaining member 60. In other words, any way capable of restricting the position of the pivot portion 32 should be regarded as modification to the handheld sander 10 of the present invention. Further, in another feasible embodiment, the drive shaft 24 may be configured as not extending into the internal accommodation 36 and connect the first gear 52, but the transmission shaft of the first gear 52 is protruded out of the pivot portion 32 and connected with the drive shaft 24. Furthermore, the sleeve portion 221 may be provided at the extension arm 30, and the first through hole 223 is provided at the sleeve portion of the extension arm 30 for passing of the first retaining member 60 therethrough. Moreover, the radial hole 563 can be provided at the follower shaft 40 for being optionally inserted therein by the second retaining member 70. As such, when the second retaining member 70 is inserted into the radial hole of the follower shaft 40, the transmission mechanism 50 is prohibited from rotation. The transmission mechanism 50 may be configured having belts and wheels or chains for transmitting rotational power.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
