DESCRIPTION

MITER SAW

Technical Field

The present invention relates to a miter saw having a circular saw blade having a safety cover to be used for bevel cutting. Background Art A miter saw for cutting a workpiece at a bevel angle ^' is well-known. Generally, the miter saw has a circular saw blade to cut a workpiece mounted on its base, and a blade cover for covering the circular saw blade for collection of dust and safety purpose. The blade cover includes a main cover and a movable cover as a safety cover to protect the circular saw blade. The safety cover is retracted into the main cover when the circular saw blade is moved downwards to cut the workpiece.

When the circular saw blade tries to cut the portion which is very close to the edge of the workpiece at a bevel angle, the end of the safety cover which has not retracted into the main cover may interfere with the edge of the workpiece. When the above interference happens, an operator has to pick up the end of the safety cover by hand, which may lead to reduce workability for the cutting process. Alternatively, if the workpiece W is thick, the rotating circular saw blade cannot reach the bottom of the workpiece, which results in failing to cut off the workpiece. Disclosure of Invention A main object of the present invention is to overcome the above-described problem and to provide a miter saw which improves workability to cut off a workpiece having a narrow

width .

The present invention provides a miter saw having a base portion, a holder portion, and a cutting portion. The base portion has a mounting surface for mounting a workpiece thereon. The holder portion stands from the base portion. The cutting portion is pivotably supported to the holder portion. The cutting portion rotatably supports a circular saw blade. The circular saw blade has a rotation axis, a side face, and a circumference. The holder portion is capable of tilting toward the base portion on the side face of the circular saw blade. The cutting portion is capable of moving in a first direction parallel to the side face of the circular saw blade and in a second direction parallel to the mounting surface of the base portion. The cutting portion includes a saw blade cover for partially covering the circular saw blade, and a movable cover for partially covering the circular saw blade. The movable cover moves to the saw blade cover in interlocking relation with a pivotal movement of the circular saw blade relative to the base portion. The movable cover includes two side cover portions, each side cover portion being positioned in proximity to the side face of the circular saw blade, and a circumferential cover portion between the two side cover portions and in proximity to a part of the circumference of the circular saw blade. The circumferential cover portion has a circumferential portion having one end, and an end member movably coupled to the one end of the circumferential portion. The end member exposes the circular saw blade when the cutting portion moves to the base portion. The end member is moved when contacting with the workpiece. Brief Description of the Drawings

The particular features and advantages of the

invention as well as other objects will become apparent from the following description taken in connection with the accompanying drawings, in which:

Fig. 1 is a side view of a miter saw according to a first embodiment of the present invention, and showing a state where the circular saw blade section is positioned at its rearmost and its uppermost position;

Fig. 2 is a front view of the miter saw and particularly showing a vertical posture thereof; Fig. 3 is a front view of the miter saw and particularly showing a leftward tilting posture thereof;

Fig. 4 is a front view of the miter saw and particularly showing a rightward tilting state thereof;

Fig. 5 is a cross-sectional view taken along the line V-V in Fig. 1 for particularly showing a blade holder;

Fig. 6 is a cross-sectional view taken along the line VI-VI of Fig. 1 for particularly showing the saw blade unit;

Fig. 7 is a side view of the miter saw, and showing a state where a blade holder contacts an end cap of the guide bar;

Fig. 8 is a perspective view showing a safety cover for a circular saw blade;

Fig. 9 is a side view partially showing the safety cover having a movable member; Fig. 10 is a front view partially showing a circular saw blade is tilted at a bevel angle and cutting a workpiece;

Fig. 11 is a side view partially showing the safety cover when the circular saw blade is cutting the workpiece; and

Fig. 12 is a side view partially showing the safety cover including a movable member during a cutting process.

Brief Explanation of Reference Numerals

I miter saw

II base

12 turntable 22 holder

31 circular saw blade

70 blade cover

71 safety cover 73 movable member Best Mode for Carrying out the Invention

A miter saw according to the present invention will be described with reference to accompany drawings. Unless otherwise noted, orientation terms, such as left, right, front, rear, up, and down, are used with respect to the normal orientation of the miter saw for normal use.

Referring to Fig. 1, a miter saw 1 generally includes a base portion 10, a holder portion 20, and a saw blade portion 30. The base portion 10 is adapted for mounting a workpiece thereon. The holder portion 20 extends upwardly from the base portion 10. The saw blade portion 30 is pivotably supported to the holder portion 20 to rotatably support a circular saw blade 31.

The base portion 10 includes a base 11 to be mounted on a floor or a table, and a turntable 12 rotatable on the base 11 in a horizontal plane. The base 11 has an upper surface 11a as a mounting surface for mounting a workpiece W thereon. An upper surface 12a of the turntable 2 is flush with the upper surface 11a of the base 11. The workpiece W such as a wood is mounted on the turntable 12 and/or the base 11. A fence 13 stands from the upper surface 11a of the base 11 and extends in a lateral direction (rightward/leftward direction) for positioning the workpiece

W on the turntable 12. A straight groove (not shown) is formed in the upper surface 12a of the turntable 12. The groove is formed at the same position as an imaginary straight line on which the circular saw blade 31 is pivoted down, thereby receiving a cutting edge of the circular saw blade 31. A knob 16 is attached to the front portion of the turntable 12 for rotating the turntable 12 relative to the base 11 about its axis and for fixing the angular rotational position (rotation angle) of the turntable 12 relative to the base 11.

The holder portion 20 extends upwardly from a rear end portion of the turntable 12, as shown in Fig. 2, and is pivotally supported to the base portion 10 to be tiltable laterally as shown in Figs. 3 and 4. The holder portion 20 includes a holder shaft 21, a holder 22, a holder fixing mechanism 40, a pair of guide bars 23a, 23b. The holder shaft 21 extends in the frontward/rearward direction at a rear side of the turntable 12. The holder shaft 21 is a pivotal axis positioned substantially coincident with the upper surface 12a of the turntable 12. The holder 22 has a lower end portion pivotally supported on the holder shaft 21. Therefore, the holder 22 is laterally tiltable with respect to the turntable 12 about the holder shaft 21 and supported by the turntable 12 with contacting with a holder support surface 12b thereof.

The holder fixing mechanism 40 is adapted for fixing a laterally tilting angle of the holder 22. The holder fixing mechanism 40 includes a support portion 41 integrally formed with the holder 22, a slider 42 for inserting between the holder support portion 12b and the support portion 41, and a lever 43 for passing through the support portion 41 and the slider 42. The lever 43 is formed with a male screw.

The slider 42 is formed with a female thread for being screwed with the male screw of the lever 43. By threadably engaging the slider 42 and the lever 43 and pivoting the lever 43, the slider 42 is movably supported to the support portion 41 in a vertical direction. By turning the lever 43 and moving the slider 42 upward, a slanting surface 41a of the support portion 41 brings into contact with a slanting surface 42a of the slider 42. The holder support surface 12b of the turntable 12 and the holder 22 then come into intimate contact with each other, thereby restricting the holder 22 from moving with respect to the turntable 12.

As shown in Fig. 2, stop portions 22a and 22b are formed at lateral end faces of the holder 22 for regulating a laterally tilting angle of the holder 22. Further, stop bolts 14, 15 vertically extend from the upper rear surface of the turntable 12 at position on a locus of the stop portions 22a and 22b. The stop bolts 14, 15 are threaded into the turntable 12. If the holder 22 is tilted in the lateral direction, the stop portion 22a or 22b is brought into abutment with the head of the stop bolt 14 or 15, whereupon the tilting angle of the holder 22 can be set. Ordinarily, the stop bolts 14, 15 are provided to laterally tilt the holder 22 at an angle of 45 degrees upon abutment with the stop portion 22a, 22b, as shown in Figs. 3 and 4. A pin 24 extends through a through-hole 22c of the holder 22 and is movable between frontmost and rearmost positions for maintaining ^• the vertical orientation of the holder 22. A stop bolt 25 horizontally extends through the holder 22. A tip end of the stop bolt 25 is positioned abuttable on an outer peripheral surface of the pin 24 when the pin 24 is positioned at its frontmost position and when the holder 22 is at its vertical position. The tip end of

the stop bolt 25 is positioned offset from the outer peripheral surface of the pin 24 when the pin 24 is displaced to its rearmost position.

The guide bar 23a, 23b have lengths equal to each other. The guide bars 23a, 23b have a tubular shape and have a circular cross-section. The guide bars 23a, 23b are fixed to the holder 22 through one ends thereof to extend parallel to each other, as shown in Fig. 2, and extend parallel to the upper surface 12a of the turntable 12 and perpendicularly to the axial direction of the circular saw blade 31, as shown in Fig. 1. When the holder 22 is at a vertical posture shown in Fig. 2, the guide bars 23a, 23b are arrayed in a vertical plane which is perpendicular to the upper surface 12a of the turntable 12. The guide bars 23a, 23b provide sufficient rigidity. Front ends of the guide bars 23a, 23b are fixed together to an end cap 26.

The saw blade portion 30 is slidable along the guide bars 23a, 23b between a rearmost position defined by the holder 22 and a frontmost position defined by the end cap 26. Further, the saw blade portion 30 is selectively secured to any position of the guide bars 23a, 23b.

The saw blade portion 30 includes a blade holder 32 slidably movable along the guide bars 23a, 23b between the holder 22 and the end cap 26, and a saw blade unit 50. The circular saw blade 31 is rotatably supported to the blade holder 32. More specifically, as shown in Fig. 5, the blade holder 32 is formed with an upper bore 32a and a lower bore 32b through which the upper guide bar 23a and the lower guide bar 23b pass, respectively. The upper bore 32a is substantially concentric with the upper guide bar 23a and has an inner diameter greater than the outer diameter of the upper guide bar 23a. The lower bore 32b is substantially

concentric with the lower guide bar 23b and has an inner diameter greater than the outer diameter of the lower guide bar 23b. A ball bearing 33 is disposed in the lower bore 32b to assist smooth sliding of the lower guide bar 23b in the lower bore 32b.

Two sliding members 34a, 34b are disposed in the upper bore 32a and in sliding contact with the outer peripheral surface of the upper guide bar 23a. Bolts 35a, 35b extend in radial direction of the upper guide bar 23a and are threadingly engaged with the blade holder 32. The bolts 35a, 35b have inner ends supporting the sliding members 34a, 34b. Thus, the sliding members 34a, 34b restrict movement of the blade holder 32 relative to the upper guide bar 23a by the threading engagement of the bolts 35a, 35b. A knob 36 is threadingly engaged with the blade holder 32 and is contactable with the bolt 35b. By fastening the knob 36, the tip end of the knob 36 is pressed against the outer surface of the guide bar 23a through the bolt 35b, so that the movement of the blade holder 32 relative to the upper guide bar 23a is restricted.

The end cap 26 is attached and fixed to the guide bars 23a, 23b to prevent the blade holder 32 from sliding off the guide bars 23a, 23b and prevent twist of the guide bars 23a, 23b. Referring to Fig. 5, a pivot shaft 37 laterally extends through the blade holder 32 in a direction perpendicular to the axial direction of the guide bars 23a, 23b. The saw blade unit 50 is pivotally movable about the pivot shaft 37. A spring 38 is disposed over the pivot shaft 37 between the blade holder 32 and the saw blade unit 50 for urging the saw blade unit 50 upward.

Referring to Fig. 6, the saw blade unit 50 includes a

blade housing 52 pivotally supported to the blade holder 32 through the pivot shaft 37, a motor housing 52 fixed to the blade housing 51, and the circular saw blade 31. The motor housing 52 houses therein a motor 53 which has a motor shaft 54. The motor 53 is fed from an external power source to rotate .

A power transmission mechanism 60 is provided in the blade housing 51 for transmitting the rotation of the motor 53 to the circular saw blade 31. The transmission mechanism 60 includes a first pulley 61, an endless belt 62, a second pulley 63, an pulley shaft 64 with a pinion 64a, and a saw blade shaft 65 having a gear 66. The first pulley 61 is fixed to the motor shaft 54. The endless belt 62 is looped between the first pulley 61 and the second pulley 63 for transferring the rotation of the first pulley 61 to the second pulley 63. The second pulley 63 is formed with the pulley shaft 64, which is meshed with the gear 66, so that the rotation is transmitted to the saw blade shaft 65.

The circular saw blade 31 is coaxially fixed and attached to the saw blade shaft 65 for its rotation. The circular saw blade 31 has a pair of side faces 31a, 31a and circumference 31b.

Further, the motor 53 is housed in the motor housing 52 such that an imaginary plane containing the side face 31a of the circular saw blade 31 intersects a part of the motor 53.

A handle 54 is provided integrally with the motor housing 52 (See Fig. 1) . The handle 55 is located on an imaginary plane containing the side face 31a of the circular saw blade 31. With this arrangement, a reaction force imparted on the saw blade unit 50 through the circular saw blade 31 during cutting can be properly received by the

handle 54. A switch 56 is provided to the handle 55 for turning on and off a motor 53, as shown in Fig. 1.

A sub-handle 57 as a transfer handle is provided integrally with the motor housing 52 (See Fig. 1) . The sub- handle 57 extends in a direction parallel with the guide bars 23a, 23b when the saw blade unit 50 is pivotaly moved to its most downward position as shown in Fig. 7. The position of the sub-handle 57 is set, considering total weight of the base 11, the turntable 12, and the saw blade unit 50.

The blade housing 51 has a blade cover 70 for covering an upper half of the circular saw blade 31, a safety cover 71 for protectively covering the circular saw blade 31 projecting out of the blade cover 70, and a link mechanism 72 for pivotally retracting the safety cover 71 into the blade cover 70.

The blade cover 70 is formed integral with the blade housing 51. The safety cover 71 is movably attached to the blade cover 70 and pivotable about the saw blade shaft 65. The safety cover 71 covers the side faces 31a, 31a and circumference 31b of the circular saw blade 31 which have not been covered by the blade cover 70, when the saw blade unit 50 is at the upper pivot position shown in Fig. 1.

The link mechanism 72 is mechanically connected to the safety cover 71 to control a movement of the safety cover 70 relative to the blade cover 70. The link mechanism 72 pivotally retracts a part of the safety cover 71 into the blade cover 70 to expose a lower part of the circular saw blade 31 to the atmosphere when the saw blade unit 50 is moved from the upper pivot position to the lower pivot position shown in Fig. 7.

Referring to Fig. 8 , the safety cover 71 has a

substantially sector shape having a pair of side portions 71A, 7IA and a circumferential portion 71B. The circumferential portion 71B is positioned between the side portions 7IA, 7IA, and positioned in proximity to the circumference 31b of the circular saw blade 31, when the safety cover 71 is assembled to the saw blade unit 50.

The circumferential portion 71B includes a curved portion 71Ba and a movable member 73. The curved portion 71Ba is positioned along most of a round edge of the side portion 71A. The movable member 71 is made from an elastic material, and may be deformed due to an external force acting thereon. In other words, the movable member 71 may change its shape due to the external force. The movable member 71 is pivotably jointed to one end 71Bb of the curved portion 71Ba. The movable member 71 has a width W and a length L. More detailed structure of the movable member 73 is shown in Fig. 9.

Referring to Fig. 9, the movable member 73 is attached to curved portion 71Ba by means of a shaft 74 and pivotable about the shaft 74. The shaft 74 is provided at the one end 71Bb of the curved portion 71Ba. It is noted that the one end 71Bb of the curved portion 71Ba is not retracted into the blade cover 70, and maintained exposed outside, when the saw blade unit 50 is positioned at the lower pivot position, as shown in Fig. 7.

A torsion spring 75 is provided between the movable member 73 and the curved portion 71Ba to urge the movable member 73 to the side portion 71A of the safety cover 71. The torsion spring 75 restricts the pivotal movement of the movable member 73 away from a peripheral edge 71Aa of the side portion 7IA. The peripheral edge 71Aa is kept contact with the movable member 73 due to an elastic force of the

torsion spring 75.

The next description will be made for explaining the operation of the miter saw 1.

For laterally tilting the saw blade unit 50, the holder 22 is first undamped with respect to the base 11 by releasing the lever 43. Then the holder 22 is tilted with respect to the base 11 in the lateral direction as shown in Fig. 3 or 4. A gravity center of the motor 53, the side face 31a, 31a of the saw blade 31, and the holder shaft 4 are aligned on an imaginary plane, so that the holder 22 can be tilted in either one of right and left directions with a constant force. The lever 43 is clamped again so that the holder 22 is fixed to the base 11 at a desired angle from the vertical direction (bevel angle) . For example, the holder 22 is inclined at angle of 45 degrees when the stop portion 22a or 22b is brought into abutment with the head of the stop bolt 14 or 15. Accordingly, the circular saw blade 31 is inclined from the vertical direction by the same angle as that of the holder 22. Thus, the miter saw 1 is ready for cutting the workpiece W from the bevel angle set by the guide bar support section 20.

In order to cut the workpiece W in a slanting direction with respect to its longitudinal direction, the knob 16 is first operated to release the engagement of the turntable 12 with the base 11. The turntable 12 is rotated respect to the base 11 by a predetermined angle (rotation angle) by means of the knob 16, while maintaining the holder 22 at its vertical position. The saw blade unit 50 is rotated integrally with the turntable 12, so that an angle of the side face 31a of the circular saw blade 31 to the fence 13 is changed. Thus, the miter saw 1 is ready for cutting the workpiece W in the slanting direction when

viewed from above.

Next, depending on the cutting length of the workpiece W, the saw blade unit 50 may be moved frontward along the guide bars 23a, 23b, as shown in Fig. 7. The motor 53 is then energized upon pressing the switch 56 for rotating the motor shaft 54, and the circular saw blade 31 is then rotated through the first pulley 61, the endless belt 62, the second pulley 63 and the saw blade shaft 65. When an operator grips the handle 55 and pushes the saw blade unit 50 downwardly against the elastic force of the spring 38, the link mechanism 72 pulls up the safety cover 71 to be pivoted about the saw blade shaft 65 and retracted into the blade cover 70, thereby exposing the lower part of the circular saw blade 31. When the saw blade unit 50 is further lowered, the circular saw blade 31 starts cutting the workpiece W to enter into the groove (not shown) on the turntable 12. Depending on the cutting length of the workpiece W, the saw blade unit 50 may be moved rearward along the guide bars 23a, 23b. When cutting the workpiece W is completed, the operator pulls up the handle 55, so that the saw blade unit 50 restores its original uppermost position by the biasing force of the spring 38.

If the slide of the saw blade unit 50 is not necessary, the blade holder 32 can be fixed to any position of the guide bars 32a, 32b by pressing the tip end of the knob 36 to the guide bars 32a, 32b.

When the saw blade unit 50 cuts the workpiece W at a bevel angle, a part of the workpiece W may enter inside the safety cover 71, depending on the cutting width or the side shape of the workpiece W, as shown in Figs. 10 and 11. In this case, when the safety cover 71 comes into contact with

the edge El of the workpiece W, the movable member 73 pivots about the shaft 74 against the elastic force of the torsion spring 75 to lift up the edge 71Ba of the circumferential portion 71B of the safety cover 71, as shown in Fig. 12, which assists smooth movement of the circular saw blade 31 during a cutting operation. In other words, the safety cover 71 is not caught by the edge El of the workpiece W and does not interfere the cutting operation of the saw blade unit 50. Further, the movable member 73 is soft and deformable, so that the movable member 73 does not damage the workpiece W, even if the movable member 73 unexpectedly hits the workpiece W.

The cutting portion of the workpiece W is substantially surrounded by the side portions 71A, 71A, and the curved portion 71Ba of the safety cover 71, and a gap between the safety cover 71 and the surface of the workpiece W can be maintained small, because there is no need to lift up the safety cover 71. Therefore, dust generated at the cutting portion of the workpiece W can be prevented from scattering out of the safety cover 71.

The structure for sliding the saw blade unit 50 with respect to the base portion 10 is not limited to the above embodiment. Any structure for relatively sliding the saw blade unit 50 with respect to the base portion 10 can be adopted.

In the above embodiment, the holder 22 is tilted relative to the base 11 by means of the turntable 12 and the holder shaft 21. However, the structure for tilting the holder 22 relative to the base 11 is not limited to the above embodiment. Any structure for relatively tilting the holder 22 relative to the base 11 can be adopted.

In the above embodiment, the endless belt 62 is used for transferring the power to circular saw blade 31 in the transmission mechanism. However, the power can be transmitted by means of mesh of gearwheels without a belt. In the above embodiment, the turntable 12 is rotatable with respect to the base 11. However, any structure of the turntable 12 is adopted, if the cutting process at a bevel angle is possible.

In the above embodiment, the link mechanism 72 is used for retracting the safety cover 71 into the blade cover 70 when the saw blade unit 50 is lowered to the base 11. However, any structure for retracting the safety cover 71 into the blade cover 70 when the saw blade unit 50 is lowered to the base 11 can be adopted. It is understood that the foregoing description and accompanying drawings set forth the embodiments of the invention at the present time. Various modifications, additions and alternative designs will, of course, become apparent to those skilled in the art in light of the foregoing teachings without departing from the spirit and scope of the disclosed invention. Thus, it should be appreciated that the invention is not limited to the disclosed embodiments but may be practiced within the full scope of the appended claims. Industrial Applicability

The invention is applicable to any types of a miter saw, which exhibits the same advantages as described above.