Belt sander having sand belt replacement apparatus

A belt sander includes a main frame, a drive roller, a driven roller, a sand belt, and a sand belt replacement apparatus. Thus, the user only needs to rotate the control handle to move the driven roller relative to the drive roller so as to change the distance between the drive roller and the driven roller so that the user can adjust the tension of the sand belt easily and rapidly, thereby facilitating the user adjusting the tension of the sand belt, and thereby facilitating the user mounting and replacing the sand belt.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a belt sander, and more particularly to a belt sander having a sand belt replacement apparatus.

2. Description of the Related Art

A conventional belt sander in accordance with the prior art shown inFIG. 10is disclosed in the applicant's U.S. Pat. No. 6,769,974-B2 and comprises a drive roller3, a driven roller4, a tension spring1, and an operation lever2. When the sand belt mounted between the drive roller3and the driven roller4is worn out for replacement, the operation lever2is pressed downward to compress the tension spring1to loosen the sand belt mounted between the drive roller3and the driven roller4, thereby facilitating the user removing the sand belt.

However, the user's one hand has to press the operation lever2and his other hand has to remove the worn sand belt and replace a new sand belt, thereby causing inconvenience to the user when mounting and replacing the sand belt. In addition, the operation lever2is easily touched and triggered by a person unintentionally, so that the sand belt is easily loosened, thereby causing danger to the user during operation of the belt sander.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide a belt sander having a sand belt replacement apparatus that can mount and replace the sand belt easily and rapidly.

Another objective of the present invention is to provide a belt sander, wherein the user only needs to rotate the control handle to move the driven roller relative to the drive roller so as to change the distance between the drive roller and the driven roller so that the user can adjust the tension of the sand belt easily and rapidly, thereby facilitating the user adjusting the tension of the sand belt, and thereby facilitating the user mounting and replacing the sand belt.

A further objective of the present invention is to provide a belt sander, wherein the user can operate the control handle to adjust the tension of the sand belt in a easier manner, thereby saving the manual work.

A further objective of the present invention is to provide a belt sander, wherein the locking bolt is screwed into the second end of the rotation shaft closely to lock the control handle on the rotation shaft, so that the control handle is locked by the locking bolt and cannot rotate the rotation shaft, thereby preventing the control handle from being rotated freely by a person unintentionally.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings and initially toFIGS. 1–6, a belt sander in accordance with the preferred embodiment of the present invention comprises a main frame10, a drive roller12rotatably mounted on the main frame10, a driven roller11rotatably mounted on the main frame10, a sand belt (not shown) mounted between the drive roller12and the driven roller11, and a sand belt replacement apparatus mounted on the main frame10for driving the driven roller11to move relative to the drive roller12so as to adjust a distance between the drive roller12and the driven roller11to facilitate a user replacing the sand belt.

The sand belt replacement apparatus includes a lifting mechanism20and an adjusting mechanism30.

The lifting mechanism20includes a lifting rod26movably mounted on the main frame10and having a hollow lower end formed with an inner thread260(seeFIG. 6) and an upper end connected to the driven roller11to drive the driven roller11to move relative to the drive roller12, a threaded rod21rotatably mounted on the main frame10and having an upper end provided with an outer thread25screwed into the inner thread260of the lifting rod26to move the lifting rod26by rotation of the threaded rod21, a first bevel gear23secured on a lower end of the threaded rod21by a locking nut24for rotating the threaded rod21, an upper positioning member27mounted on the main frame10and mounted on the lifting rod26to facilitate movement of the lifting rod26, and a lower positioning member22mounted on the main frame10and mounted on the lower end of the threaded rod21to facilitate rotation of the threaded rod21.

The adjusting mechanism30includes a rotation shaft33rotatably mounted on the main frame10, a second bevel gear35secured on a first end of the rotation shaft33to rotate therewith and meshing with the first bevel gear23for rotating the first bevel gear23, a support member32secured on the main frame10and mounted on a mediate portion of the rotation shaft33to support the rotation shaft33, a control handle34secured on a second end of the rotation shaft33for rotating the rotation shaft33, a locking bolt36extended through the control handle34and screwed into the second end of the rotation shaft33, and a pivot seat31secured on the main frame10and mounted between the rotation shaft33and the control handle34. The second end of the rotation shaft33is protruded outward from the main frame10, and the pivot seat31is mounted on the second end of the rotation shaft33and rested on the control handle34to facilitate the control handle34rotating the rotation shaft33. The locking bolt36is mounted on a connection of the control handle34and the rotation shaft33.

When the locking bolt36is screwed into the second end of the rotation shaft33closely to lock the control handle34on the rotation shaft33, the control handle34is locked by the locking bolt36and cannot rotate the rotation shaft33, and when the locking bolt36is unscrewed from the second end of the rotation shaft33, the control handle34is unlocked from the locking bolt36and can rotate the rotation shaft33.

In operation, referring toFIGS. 6–9with reference toFIGS. 1–5, when the control handle34is rotated in the counterclockwise direction, the rotation shaft33and the second bevel gear35are rotated in the counterclockwise direction, so that the first bevel gear23is rotated in the counterclockwise direction so as to rotate the threaded rod21and the outer thread25in the counterclockwise direction. Thus, the outer thread25of the threaded rod21is rotated in the counterclockwise direction, so that the outer thread25of the threaded rod21is screwed into the inner thread260of the lifting rod26to drive the lifting rod26to move downward so as to drive the driven roller11to move downward. Thus, the driven roller11is moved toward the drive roller12to shorten the distance between the drive roller12and the driven roller11so as to loosen the sand belt, thereby facilitating the user replacing the sand belt.

Alternatively, when the control handle34is rotated in the clockwise direction, the rotation shaft33and the second bevel gear35are rotated in the clockwise direction, so that the first bevel gear23is rotated in the clockwise direction so as to rotate the threaded rod21and the outer thread25in the clockwise direction. Thus, the outer thread25of the threaded rod21is rotated in the clockwise direction, so that the outer thread25of the threaded rod21is unscrewed from the inner thread260of the lifting rod26to drive the lifting rod26to move upward so as to drive the driven roller11to move upward. Thus, the driven roller11is moved outward relative to the drive roller12to increase the distance between the drive roller12and the driven roller11so as to tighten the new sand belt, thereby facilitating the user mounting the new sand belt.

Accordingly, the user only needs to rotate the control handle34to move the driven roller11relative to the drive roller12so as to change the distance between the drive roller12and the driven roller11so that the user can adjust the tension of the sand belt easily and rapidly, thereby facilitating the user adjusting the tension of the sand belt, and thereby facilitating the user mounting and replacing the sand belt. In addition, the control handle34has a radius of rotation greater than the diameter of the second bevel gear35, and the first bevel gear23has a diameter greater than that of the outer thread25of the threaded rod21, so that the user can operate the control handle34to adjust the tension of the sand belt in a easier manner (because the applying force arm is greater than the resistance force arm), thereby saving the manual work. Further, the locking bolt36is screwed into the second end of the rotation shaft33closely to lock the control handle34on the rotation shaft33, so that the control handle34is locked by the locking bolt36and cannot rotate the rotation shaft33, thereby preventing the control handle34from being rotated freely by a person unintentionally.