JPH0618772Y2 - Hand grinder - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a hand grinder most suitable for grinding a recess or a narrow place.

[Prior art]

In a conventional hand grinder, a rotary grinding tool such as a disk grinding tool is attached to a rotary shaft protruding from a grip portion, and the grinding tool is rotated in one direction to perform a grinding operation.

By the way, when the grinding tool is rotated in one direction to perform grinding work, the grinding tool is rotated at a relatively high speed, and due to excessive usage, an excessive force may be applied to the grinding tool depending on the shape of the surface to be ground. The grinding tool could be damaged. In such a case, the fragments may be scattered and even cause an injury accident to the grinding operator, which is a problem. Furthermore, when the reaction force is applied to the grip by the frictional resistance between the grinding tool and the surface to be ground, the rotating force of the grinding tool causes the operator to constantly apply force to the grip to prevent the grip from swinging around. It is necessary to insert and support, but when grinding a dent or a narrow place, or when grinding a deep place, the support of the gripping part may be insufficient, so in this way,
If the support is not sufficient, not only the work is dangerous as described above, but also the finished state of the surface to be ground deteriorates in the grinding work of many curved surfaces and irregularities and the finishing work such as casting or press dies. There was a risk that

[Problems to be solved by the invention]

As described above, in the conventional hand grinder of the type that rotates the grinding tool in one direction, there is a problem that the finished state of the surface to be ground may be lowered due to danger or unstable support of the gripping part. Therefore, the present invention is intended to solve the above-mentioned problems, and there is no risk of damaging the grinding tool during the grinding work, and the work can be performed even in a place where it is difficult to work. An object of the present invention is to provide a hand grinder capable of performing a stable work even on a ground surface having a complicated shape without giving unnecessary trouble to a person and capable of performing a grinding work in a good finished state.

[Means for solving problems]

The present invention, as a means for solving the above problems, causes a spindle that reciprocally rotates within a range of about one rotation to project from a grasping portion, and the projected spindle has a holder bent in an L shape. One end is fixed so that it can be inserted and removed, and the other end of the holder is removably attached to the rod of a grinding tool having a grinding grain surface at the tip of the rod in a direction perpendicular to the axis of the spindle. This is a structure in which a chuck portion that operates is provided.

[Action]

In the hand grinder of the present invention, since the spindle reciprocates within a range of about one rotation, when the grinding tool whose rotation direction is reversed by the spindle is pressed against the surface to be ground, the left and right vibrations of the gripping part are averaged. Is transmitted, and the surface to be ground is ground without applying an excessive rotational force.

In addition, the grinding tool attached to the chuck part grinds the surface to be ground while repeatedly performing circular arc motion with the radius from the shaft center to the grinding grain surface centering on the spindle, so that the efficiency of dents and concave curved surfaces is improved. It enables specific grinding.

〔Example〕

The hand grinder of the present embodiment uses a motor 1 as a driving source, and a spindle rotatably supported by a holding portion 2 incorporating the motor in a direction perpendicular to a motor shaft 3 via ball bearings 4 and 5. 6 has the same spindle 6,
As will be described in detail below, the rotation of the motor shaft 3 is converted into a swing motion and transmitted, so that the motor shaft 3 reciprocally rotates at a relatively small angle.

That is, one end of an arm 7 is spline-fitted and fixed to the intermediate portion of the spindle 6, and the other end of the arm 7 is provided with a cylindrical surface 8 whose axis is parallel to the spindle 6. Is formed by cutting out a part of the outer peripheral surface of the arm 7 located at the longitudinal end of the arm 7. A slider 10 is fitted into the support ring 9 while being in sliding contact with the cylindrical surface 8 and concentric with the surface 8 and relatively rotatable. The axial displacement of the slider 10 with respect to the support ring 9 is restricted by a stopper such as a snap ring (not shown). On the other hand, the motor shaft 3 has
Fix the eccentric shaft 11 whose tip is eccentric with respect to the coaxial 3,
A ball bearing 12 having a relatively small outer shape, which functions as a guide roller, is rotatably positioned and supported by a pair of stop rings 13 at the tip eccentric portion of the eccentric shaft 11. The slider 10 is slidably contactable with the outer peripheral surface of the ball bearing 12, and as shown in FIG. 3, the spindle 6 has a shaft length of at least twice the eccentric amount E of the eccentric shaft 11. By forming a long hole 14 having in the axial direction (up and down direction),
The outer peripheral portion of the ball bearing 12 is loosely fitted in the elongated hole 14. When the eccentric shaft 11 is rotationally driven, the ball bearing 12 which rotates eccentrically in response to the eccentric shaft 11 moves up and down relatively inside the elongated hole 14, so that the displacement component of the ball bearing 12 in the horizontal direction substantially slides. Transmitted to child 10,
The arm 7 swings integrally with the spindle 6 about the axis of the spindle 6.

The spindle 6 projects outward from the lower end of the grip portion 2, and an L-shaped block 30 is attached to the projecting end of the push screw 3 so that the L-shaped block 30 can take an arbitrary rotational position with respect to the spindle 6.
A chuck portion 33 having a central hole 32 oriented in a direction perpendicular to the axis of the spindle 6 is formed at the bent end of the L-shaped block 30. Similar to a so-called drill chuck, this chuck portion 33 is provided with a plurality of vertical splits radially with respect to the central hole 32 to form a plurality of support pieces 16 which can be cantilevered in the centrifugal centrifuging direction, and at the same time, the support pieces. A tightening operation ring 19 having an upward tapered surface 18 that engages with a downward tapered surface 17 formed on the outer periphery of the distal end portion of 16 on the inner peripheral surface of the distal end portion is screwed to the outer peripheral portion of the support piece 16. The chuck 33 is for removably mounting the grinding tool 21, and the grinding tool 21 has, for example, a polishing paper 23 made of paper, cloth, or resin having an abrasive grain fixing surface 22 on the bottom surface.
Is a disc-shaped grinding tool for rotary grinding, which is replaceably attached to the bottom surface of the disc-shaped pad 24 via an adhesive or an adhesive, and a rod 25 is projected above the center of the pad 24. In this grinding tool 21, the rod 25 is inserted into the center hole 15 of the chuck portion 20, and the tightening operation ring 19 is inserted.
Rotate in the tightening direction to secure the rod 2 with a plurality of support pieces 16.
By fixing 5 by clamping, it can be mounted and fixed on the spindle 6.

Next, the operation of this embodiment will be described.

When the motor 1 is started in a state where the grinding tool 21 is attached and fixed to the chuck portion 33, the eccentric shaft 1 is integrated with the motor shaft 3.
1 is rotationally driven, and the ball bearing 12, which is eccentrically rotated in response to the rotational movement, moves up and down relatively inside the elongated hole 14, so that the slider 10 substantially has the ball bearing 1
Displacement of two horizontal components is transmitted. That is, assuming that the eccentric amount of the eccentric shaft 11 with respect to the motor shaft 3 is E, the displacement amount of the ball bearing 12 with respect to the shaft center of the motor shaft 3 takes the maximum distance E in the vertical and horizontal directions, respectively. Is designed to move up and down relatively inside the slot 14 having a length more than twice the eccentricity E in the vertical direction.
Substantially no displacement of the vertical component of 2 is received, and the horizontal displacement of the bearing 12 is followed in accordance with the displacement of the horizontal component. Therefore, when the slider 10 is repeatedly displaced in the left-right direction, the support ring 9 into which the slider 10 is fitted rotates slightly around the slider 10 in response thereto, and the arm 7 Is oscillated around the spindle 6, and the spindle 6 is reciprocated at a slight rotation angle of 5 to 10 degrees.

In this state, when the abrasive grain fixing surface 22 of the polishing paper 23 is pressed against the surface to be ground, the grinding tool 21 mounted on the chuck portion 33 reaches the abrasive grain fixing surface 22 from the axial center of the spindle 6. The surface to be ground is ground while repeatedly performing an arc motion with a radius. Therefore, when grinding a dent or a concave curved surface, the insertion depth of the rod 25 into the central hole 32 is adjusted according to the size and depth of the dent and the curvature of the curved surface, and the axial center of the spindle 6 is adjusted. If the radius reaching the abrasive grain fixing surface 22 is set to a desired value, it is possible to efficiently grind a dent or a concave curved surface by means of the planar abrasive grain fixing surface 22, and the finished state is good. Become. Especially, when the grinding work is performed in a narrow place or the inner part is ground, the fixing position of the L-shaped block 30 with respect to the spindle 6 is adjusted according to the convenience of the operator. At this time, since the polishing marks on the surface to be ground are arc-shaped with the axis of the spindle 6 as the center, the polishing marks can be reliably crossed by simply shifting the hand grinder, for example, in the downward direction on the surface to be ground. However, no polishing marks remain. If the grain size of the abrasive grains is small, it is of course possible to carry out mirror finish.

Further, during the grinding operation, the reaction force due to the frictional resistance between the abrasive grain fixing surface 22 and the surface to be ground does not act on the gripping portion 2 as an excessive rotational force, so that the gripping portion 2 is held during the grinding operation. There is no risk of being swung around, and the operator can support the grip portion 2 in a stable holding state. According to this embodiment, for example, it can be used for paint removal of a vehicle body that is relatively complicatedly formed by many irregularities and curved surfaces, and finishing work of a die for casting or pressing. When the hand grinder is used, the orientation of the gripping portion 2 changes vertically and horizontally according to the orientation and shape of the surface to be ground, and therefore when working in a recess or in a narrow space, the abrasive grain fixing surface 22 Even if the entire surface of the polishing pad is not brought into surface contact with the surface to be ground, the contact portion with the surface to be ground is changed at various angles, and at that time, the peripheral edge of the polishing paper 23 or the pad 24 is brought into contact with the surface to be ground. Even if it does, since a large rotational torque is not transmitted to the spindle 6, the grip portion 2 is not swung. Therefore, the supporting state of the grip portion 2 is not unstable, and the polishing paper 23 is not repelled,
Safe and stable grinding work is possible, for example,
The surface to be ground is not excessively scraped off due to local contact between the peripheral edge of the polishing paper 23 or the pad 24 and the surface to be ground, and the base is damaged in the paint removing work and the finished surface in the mold finishing work is not removed. Roughness can be prevented and a good ground surface can be obtained.

Further, in the course of the grinding operation, an unreasonable force may be applied to the bonding surface between the polishing paper 23 and the pad 24, or the polishing paper 23 may fall off the pad 24 due to the deterioration of the bonding force over time. Even when it occurs, the polishing paper 23 that reciprocates at a slight rotation angle does not generate an excessive centrifugal force.
The dropped polishing paper 23 does not scatter.

Although the hand grinder of the present invention has been described in detail based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention.

For example, as a mechanism for reciprocating the spindle within a range of about one rotation, it is possible to use a four-bar linkage mechanism or its deformation mechanism or a reversible motor. Further, the grinding tool may be a grindstone having a disk shape, a cylindrical shape, a conical shape, or the like.

[Effect of device]

Since the hand grinder of the present invention has a spindle that reciprocates within a range of about one rotation and a grinding tool for rotary grinding is attached to the spindle, the friction between the grinding tool and the surface to be ground is increased. Excessive rotation torque does not act on the gripping part due to resistance, and even in dents, narrow places, or even deep parts, the gripping part can be changed vertically or horizontally depending on the direction and shape of the surface to be ground, It is possible to perform grinding work by changing the angle in various ways and by bringing the peripheral edge of the grinding tool into contact with the surface to be ground, so that the gripping part is the same as when using a conventional hand grinder. You can safely perform grinding work without being shaken around and the support of the gripping part becomes unstable, and the grinding tool will not be easily damaged, and it is possible to prevent roughening and damage of the ground finish surface. Good grinding It is possible to obtain a safe operation.

Even if the grinding tool is damaged during the grinding work, the grinding tool that swings and reciprocates at a small rotation angle does not generate an excessive centrifugal force, and the grinding tool is damaged. It is possible to prevent personal accidents caused by accidents.

Further, the grinding tool mounted on the chuck part of the L-shaped bent holder moves the surface to be ground while repeatedly performing circular arc motion with the radius from the shaft center to the grinding abrasive grain surface around the spindle. When grinding a dent or a concave curved surface, the rod insertion depth to the chuck is adjusted according to the size and depth of the dent and the curvature of the curved surface, and grinding is performed from the spindle axis. By setting the radius to reach the abrasive grain surface to a desired value, it is possible to efficiently grind a dent or a concave curved surface by means of a planar abrasive grain surface, and the finished state becomes good. Further, when the grinding work is performed in a narrow place or the inner part is ground, the fixing position of the L-shaped holder with respect to the spindle can be adjusted according to the convenience of the operator.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of a hand grinder according to the present invention. FIG. 1 is a vertical sectional side view showing a main part of the hand grinder, and FIG. 2 is a line AA in FIG. Sectional view, 3rd
The drawing is a sectional view taken along the line BB in FIG. 3 ... motor shaft, 6 ... spindle, 7 ... arm, 8
…… Cylinder surface, 9 …… Support ring, 10 …… Slider, 11
...... Eccentric shaft, 12 ...... Ball bearing, 14 ...... Long hole, 21 ...... Grinding tool, 22 ...... Abrasive grain fixed surface, 23 ...... Abrasive paper, 24 ...... Disc-shaped pad, 30 ...... L-shaped block , 33 …… Chuck part.

Claims (1)

[Scope of utility model registration request] 1. A spindle reciprocating within a range of about one rotation is projected from a grasping portion, and one end of a holder bent in an L shape is fixed to the protruding spindle so that the holder can be inserted and removed. A hand grinder comprising, at the other end of the holder, a chuck part for detachably mounting the rod of a grinding tool having a grinding grain surface at the tip of the rod in a direction perpendicular to the axis of the spindle.