JP2013107182A - Disk grinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk grinder which has a simple structure to achieve a rotation stop mechanism of a wheel guard for preventing scattering of cutting powder, and whose cost reduction is achieved.SOLUTION: The disk grinder is provided with a stopper portion (a wall 10) for closing at a part of a groove 6 for preventing coming-off of a wheel guard 20 provided on a spindle cover 4 to configure such that when the wheel guard 20 rotates, the wall 10 and a projection 22 for preventing coming-off of the wheel guard 20 make contact, thereby limiting the rotation angle of the wheel guard 20. Even when the wheel guard 20 happens to rotate from an intended position due to some operations during operation of the disk grinder, the projection 22 abuts to the wall 10. Accordingly, an opening 20a of the wheel guard 20 is not directed toward an operator side to thereby prevent cutting powder from being scattered toward the operator side.

Description

  The present invention relates to a disc grinder, and more particularly to a disc grinder with an improved wheel guard detent mechanism that covers a tip tool.

  The disk grinder performs operations such as grinding by rotating a tip tool with a motor as a drive source. A grindstone or a diamond wheel is used as the tip tool. In the disc grinder, for safety measures, a part of the tip tool is covered with a wheel guard, and the mounting position of the wheel guard can be changed according to work. Here, a wheel guard mounting structure of a conventional disc grinder will be described with reference to FIGS. FIG. 4 is a partial perspective view showing a configuration around a gear cover and a spindle cover in a conventional disc grinder, and is a perspective view of the tip portion of the disc grinder 101 as viewed from below. The gear cover 13 is a cover fixed to the front side of a cylindrical motor housing that houses a motor (not shown), and is a housing portion that covers a gear such as a bevel gear (not shown). The spindle 3 is rotatably held by a spindle case 104 and extends downward from the gear cover 13. The spindle case 104 is integrally formed of a metal such as aluminum, and is fixed to the gear cover 13 with four screws 7 through screw holes arranged around the spindle 3. A mounting surface 105 is formed on the outer periphery of the spindle case 104 in the vicinity of the central portion in the axial direction (vertical direction) to hold a mounting ring 121 of a wheel guard 120 described later. The mounting surface 105 has an axial direction (vertical direction). A groove 106 having a certain width and continuous in the circumferential direction is formed.

  FIG. 5 is a top view of the wheel guard 120 in the conventional disc grinder 101. The wheel guard 120 is a member manufactured by pressing a metal plate, for example, and has a substantially semicircular shape when viewed from above so as to cover almost half of the rotary tool. Near the center of the semicircle, there are provided an attachment ring 121 and a fastening means 124 comprising screws and bolts for fastening the attachment ring 121. The attachment ring 121 is a strip-shaped metal plate, and is divided at one place in the circumferential direction, and its end extends radially outward to form a bent portion 121a. The bent portion 121a includes a bolt and a nut. It functions as a seating surface of the tightening means 124. The inner surface of the attachment ring 121 is attached to the attachment surface 105 which is a cylindrical outer periphery of the spindle case 104, and the protrusion 122 of the attachment ring 121 is engaged with the groove 106.

  The wheel guard 120 of the disc grinder 101 as described above loosens the fastening means 124 to loosen the fastening to the mounting surface 105 of the mounting ring 121, so that the wheel guard 120 can be moved to an arbitrary circumferential direction around the rotation axis of the spindle 3. The position can be changed. FIG. 6 shows this state. In FIG. 6, the position of FIG. 6, that is, the edge portion 120 a portion of the wheel guard 120, with respect to the vertical axis with respect to the motor axis of the disc grinder 101 (the axis of rotation of the motor and the longitudinal center line of the disc grinder). Shows a state of being rotated by about 110 degrees counterclockwise as indicated by an arrow from a state where is at a vertical line position (this is called a position of θ = 0 °). In the conventional disc grinder 101, the tightening means 124 of the wheel guard 120 has a structure that does not come into contact with the convex portion (wall portion) of the gear cover 13, so that the wheel guard 120 has an arbitrary 360 ° centering on the spindle 3. It has a structure that can be fixed at the location.

  However, in recent years, even if the wheel guard 120 is disengaged from the position where it was fixed during work due to an impact such as loosening of the fastening means 124 for mounting or hitting the wheel guard 120 due to an international standard regarding electric tools. Therefore, it is required to take some measures so that the opening (edge portion 120a) of the wheel guard 120 does not face the worker side. Therefore, a predetermined position, for example, the edge portion 120a of the semicircular wheel guard 120 is limited so that it cannot be rotated in the direction indicated by the arrow beyond the position rotated 60 degrees from the vertical line (the position where the line and the edge portion coincide). Need arises. In order to solve this problem, as shown in FIG. 4, in the technique of Patent Document 1, a stop piece 111 is attached to the gear cover 113 to limit the rotation of the wheel guard 120 over a predetermined rotation. The stop piece 111 is fixed by using a screw for attaching the gear cover 13 to the motor housing. By providing the stop piece 111, as shown in FIG. 7, the rotation of the wheel guard 120 is restricted so as not to rotate by θ = 60 ° or more.

JP 2011-125983 A

  The stop piece 111 as shown in FIG. 4 can limit the rotation angle of the wheel guard 120 without changing the configuration of the wheel guard 120. However, the stop piece 111 needs to be firmly made of a metal member, has a complicated shape, and the unit cost is high at present.

  The present invention has been made in view of the above background, and an object of the present invention is to provide a grinder that realizes a rotation stop mechanism for a wheel guard that prevents scattering of cutting powder to an operator without changing the conventional component configuration. Is to provide.

  Another object of the present invention is to provide a grinder that realizes a rotation stop mechanism of a wheel guard by adding a simple member and minimizes cost increase.

  Still another object of the present invention is to provide a grinder that realizes a wheel guard rotation stop mechanism without impairing the usability of the wheel guard position adjusting function.

  Still another object of the present invention is to provide a grinder that realizes a structure that can limit the rotation of the wheel guard with a simple structure and at a low cost without using a complicated shaped part such as a stop piece. It is in.

  According to one aspect of the present invention, a housing portion incorporating a motor, a gear cover incorporating a bevel gear for reducing the motor power and converting the direction of the rotation axis to a right angle, and the gear cover orthogonal to the rotation axis of the motor. A spindle cover that covers the spindle with the rotation axis extending in the direction of the wheel, and a wheel guard that covers about half of the circumferential angle of the circular grindstone attached to the spindle cover, so that the wheel guard can be fixed at a predetermined position in the circumferential direction. In the grinder, the spindle cover is fixed to the gear cover by a plurality of screws that are tightened in a direction perpendicular to the rotation axis of the motor. When the convex portion provided on the wheel guard comes into contact with the groove for preventing and rotating the wheel guard provided on the spindle cover, the wheel guard is difficult to be removed from the spindle direction. The spindle cover is formed with an insertion position of a protrusion for preventing the wheel guard from coming off. A part of the circumferential direction of the groove provided for retaining this is left without forming the groove. The wall in a part of the groove provided for preventing the wheel guard from coming off and the convex portion of the wheel guard are in contact with each other.

  According to the present invention, by providing the wall portion in a part of the wheel guard retaining groove provided on the spindle cover, the convex portion for retaining the wheel guard when the wheel guard rotates when the grinder is used. And the above-mentioned wall part come into contact, the wheel guard comes off from the intended position due to troubles such as hitting the wheel guard, and the opening part faces the worker side, and the scattering of cutting powder is caused on the worker side. Can be prevented.

It is a fragmentary perspective view which shows the structure around the gear cover of the Example of this invention, and a spindle cover. It is a top view of the wheel guard of the Example of this invention. It is a bottom view which shows the structure around the gear cover of an Example of this invention, a spindle cover, and a wheel guard. It is a fragmentary perspective view which shows the structure around the gear cover and spindle cover in the conventional disc grinder. It is a top view of the wheel guard in the conventional disc grinder. It is a partial bottom view for demonstrating the angular position movement condition of the wheel guard in the conventional disc grinder (the 1). It is a partial bottom view for demonstrating the angular position movement condition of the wheel guard in the conventional disc grinder (the 2).

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, parts having the same function are denoted by the same reference numerals, and repeated description is omitted. Further, in this specification, description will be made assuming that the front, rear, left, right, and up and down directions are directions shown in the drawing.

FIG. 1 is a perspective view of a disc grinder 1 according to an embodiment of the present invention as seen from the lower side. The gear cover 13 is fixed to the front side of a motor housing (not shown) that accommodates the motor therein by four mounting screws 7 that are tightened in a direction parallel to the rotation shaft of the motor (not shown). The spindle 3 is rotatably held by the spindle cover 4 and extends downward from the gear cover 13. The spindle cover 4 is integrally formed of a metal such as aluminum, and is fixed to the gear cover 13 by four mounting screws 8 through screw holes arranged around the spindle 3. A mounting surface 5 that is a cylindrical surface is formed on the outer periphery of the spindle cover 4 in the axial direction (vertical direction). A groove 6 having a certain width is formed in the (vertical direction). The groove 6 is basically an annular groove formed continuously in the circumferential direction, and is formed in a groove shape or a concave shape so as to be recessed inward from the mounting surface 5. As a characteristic configuration of the present embodiment, in order to limit the rotation angle of the wheel guard 20, the cylindrical groove 6 has a wall portion 10 (stopper portion) that closes the groove-shaped portion in a part of the circumferential direction. It is formed.
The projections (projections) 22 provided on the wheel guard 20 are applied to the grooves 6 provided on the spindle cover 4 so that two effects of retaining and preventing rotation can be obtained.

  A bevel gear (not shown) attached to the rotating shaft of the motor and a bevel gear (not shown) attached to the upper end of the spindle 3 are arranged in the gear cover 13, and the rotation of the motor is performed by these two bevel gears. The number is decelerated and the spindle 3 as the output shaft rotates. A tip tool (not shown) is attached to the tip (lower end) of the spindle 3, for example, a circular grindstone is attached. On both the left and right sides of the gear cover 13, screw holes 9 are provided for fixing side handles that are detachably fixed.

  FIG. 2 is a top view of the wheel guard 20 of the present embodiment. The wheel guard 20 widens the inner diameter of the mounting ring 21 by loosening the screws forming the tightening means 24 (relaxes the tightening), and the wheel guard 20 is positioned at any position in the circumferential direction around the rotation axis of the spindle 3. It can be changed. The attachment ring 21 has a C-shape and is fixed to the wheel guard 20 by welding. Bending portions 21a and 21b are formed at both ends of the mounting ring 21, and screw holes (not shown) are formed in the bending portions 21a and 21b. In this embodiment, bolts and nuts are used as the fastening means 24 for connecting these screw holes, and the fastening ring 24 is fastened to fix the mounting ring 21 to the cylindrical mounting surface 5 of the spindle cover 4. At this time, the protrusion 22 protruding inwardly on the inner peripheral surface of the attachment ring 21 is attached so as to be accommodated in a groove 6 (attachment surface) for retaining the recess formed on the outer peripheral surface of the spindle cover 4. The protrusion 22 can move in the circumferential direction by loosening the tightening means 24 as long as it is located inside the retaining groove 6, but the wall 10 (see FIG. 1) at one end in the circumferential direction. Therefore, the rotation of the wheel guard 20 (counterclockwise rotation when viewed from above) is restricted at a predetermined position by the convex portion 22 moving in the circumferential direction. Although not visible in FIG. 1, a similar wall is formed at the other circumferential end of the groove 6, so that the wheel guard 20 rotates in the opposite direction (counterclockwise rotation as viewed from above). Is also limited at a predetermined position.

  FIG. 3 is a bottom view showing a configuration around the gear cover 13, the spindle cover 4, and the wheel guard 20 of the present embodiment. In FIG. 3, when the rotation angle is θ = 60 (the same positional relationship as in FIG. 7), the convex portion 22 is at the position indicated by the dotted line. Although not visible in the drawing, the convex portion 22 is in contact with the wall portion 10. Therefore, the wheel guard 20 cannot rotate relative to the spindle cover 4 at θ> 60, and the wheel guard 20 rotates greatly from the intended position due to troubles such as hitting the wheel guard 20. Thus, it is possible to prevent the opening from facing the worker side.

  As mentioned above, although this invention was demonstrated based on the Example, this invention is not limited to the above-mentioned Example, A various change is possible within the range which does not deviate from the meaning. For example, in the above-described embodiment, the convex portion 22 formed on the wheel guard 20 as the anti-rotation means functions by contacting the wall portion 10 of the spindle cover 4, but is not limited to this configuration. Instead of the convex portion 22 of the wheel guard 20, a hole is formed in the radial direction of the mounting ring 21, a female screw is formed in the hole, and a bolt penetrating from the outside in the radial direction is arranged to connect the bolt and the mounting ring 21. You may make it form the convex part 22 as a structure which welds.

DESCRIPTION OF SYMBOLS 1 Disc grinder 3 Spindle 4 Spindle cover 5 Mounting surface 6 Groove 7, 8 Screw 9 Screw hole 10 Wall part 12 Wheel guard removal prevention convex part insertion position 13 Gear cover 20 Wheel guard 21 Mounting ring 21a, 21b Folding of mounting ring Curved portion 22 Convex portion 24 Tightening means 101 Disc grinder 104 Spindle case 105 Mounting surface 106 Groove 111 Stop piece 113 Gear cover 120 Wheel guard 120a Edge portion 121 Mounting ring 121a Bending portion 122 Projection 124 Tightening means

Claims (3)

A gear cover provided in front of a motor housing containing the motor;
A spindle extending from the gear cover in a direction substantially perpendicular to the rotation axis of the motor;
A spindle cover that covers the spindle and has a substantially cylindrical mounting surface on the outer periphery;
A grinder having a wheel guard that covers about half of a circumferential angle of a rotary tool attached to the spindle cover, and capable of fixing the wheel guard at a predetermined position in a circumferential direction of the attachment surface;
The wheel guard is provided with a mounting ring for fixing to the mounting surface of the spindle cover and a protrusion protruding inward from the mounting ring,
The mounting surface of the spindle cover is provided with an annular groove extending in the radial direction for fitting the protrusion and preventing the spindle cover from coming off in the axial direction,
A disc grinder characterized in that a stopper portion that closes the groove portion is provided in the annular groove portion so as to restrict the wheel guard from rotating more than a certain angle. The mounting ring is substantially C-shaped and welded to the wheel guard;
Bends are formed at both ends of the mounting ring;
2. The disc grinder according to claim 1, wherein the mounting ring is fixed to the mounting surface of the spindle cover by tightening a tightening means for connecting a screw hole formed in the bent portion.   3. The disc grinder according to claim 1, wherein the stopper portion is provided at two locations of the groove portion and restricts the movement of the wheel guard in the double rotation direction.

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