JPS632663A - Motor driven disk grinder - Google Patents

Abstract

PURPOSE:To improve a vibration isolating property and carry out the double electric insulation of a casing by forming said casing with a glass fiber reinforced plastic. CONSTITUTION:A motor driven disk grinder has a casing 10 in the inner periphery of which a stator 13 is fixed, a rotor 14 which is rotated in the stator 13, and a grinding wheel 21 which is directly connected to the rotary shaft 14a of the rotor. The casing 10 is formed with a glass fiber reinforced plastic. Thereby, the vibration of the casing can be reduced nearly to half due to a damping effect, while effecting a double electric insulation structure without need for forming the casing 10 into a double structure as in the conventional case. Also, since the casing 10 is machined by means of injection molding, machining after molding is not necessary, greatly lowering a cost.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric disc grinder, and particularly to an electric disc grinder whose casing is made of glass fiber reinforced plastic.

[Prior Art] Portable electric disc grinders are widely used in grinding operations during the manufacturing process of large structures such as ships, bridges, and plant equipment.

FIG. 2 is a perspective view showing the configuration of a first conventional electric disc grinder. In this figure, the symbol I is, for example, Mg.
The casing is made of a light metal such as an alloy, and is composed of an upper cover 2 and a casing 3, and a main handle 4 and a sight handle 5 are fixedly attached to the outer peripheral surface of the casing 3. A stator core of an induction motor (path shown) is fixedly attached to the inner circumferential surface of the casing 3 via reinforcing ribs (path shown), and a disc is attached to the lower end of the rotating shaft of the rotor that is rotationally driven within the stator core. A grindstone 6 of a shape is combined.

Further, the whetstone 6 is covered by a fan-shaped whetstone cover 7,
The inner peripheral part of the grindstone cover 7 is fixedly attached to the casing 3.

In such a configuration, grinding work is performed by rotating the grindstone 6 at high speed using an induction motor.

During this grinding, the pressing load generated by pressing the electric disc grinder against the workpiece and the grinding wheel cover 7
The force due to the tightening is directly applied to the casing 1.

On the other hand, a second electric disc grinder is also known which has a double-structured casing in which the outer periphery of the light metal canong 1 of the electric disc grinder described above is further covered with a plastic casing.

[Problems to be Solved by the Invention] The first conventional electric disc grinder described above has the following problems.

(1) Since the casing 1 is made of light metal, vibrations transmitted to the hands and arms through the handle are large.

(2) Since the stator core is fixed to the casing 1 via reinforcing ribs, it does not have an electrical double insulation structure. Therefore, electricity is likely to leak into the casing l during work in rainy weather or the like.

(3) Since the casing is cast using relatively expensive light metal and then cut to obtain predetermined dimensions, manufacturing costs are high.

Furthermore, the second electric disc grinder having the double-structured casing had the following drawbacks.

(+) Weight increases.

(2) The cost increases because the number of manufacturing steps increases.

In view of the above circumstances, it is an object of the present invention to provide an electric disc grinder that can improve vibration isolation and provide double electrical insulation of the casing.

[Means for solving the problems] The present invention includes a casing having a stator fixed to its inner peripheral surface;
An electric disc grinder comprising a rotor rotationally driven within the stator and a grindstone directly connected to the rotating shaft of the rotor, characterized in that the casing is made of glass fiber reinforced plastic. .

[Function] According to the present invention, since the casing is made of glass fiber reinforced plastic, the damping effect improves the vibration damping properties, and electrical double insulation can be achieved.

[Example 1] An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the configuration of this embodiment.

In this figure, the reference numeral 10 is a casing made of glass fiber reinforced plastic such as glass fiber-filled polycarbonate, and is composed of a cylindrical body 11 and a disk-shaped upper cover 12 fixedly attached to the cylindrical body 11. has been done. A main handle and a side handle (see FIG. 2) are fixedly attached to the outer peripheral surface of the cylindrical body 11. Reinforcing ribs lla, lla, . . . extending in the axial direction are formed at regular intervals on the inner circumferential wall of the cylinder II. Also,
A stator 13 is fixed to the inner peripheral wall of the cylindrical body 11.

The stator 13 is composed of a stator core 13a and a coil +3b.

On the other hand, a rotor 14 is rotatably supported on a rotating shaft 14a with a slight gap between the inner periphery of the stator core 13a. The upper end of the rotating shaft 14a is supported by the holding portion 12a of the upper cover 12 via a bearing 16. Rotating shaft 14a
A grindstone mounting shaft 17 having a common axis with the rotating shaft 14a is fixedly attached to the lower end of the grindstone. The mounting shaft 17 is the bearing 1
It is supported by the holding part 11b of the cylinder body 11 via 8.

Note that the stator 13 and rotor 14 constitute an induction motor 15.

Further, an umbrella-shaped fixed flange 19 that rotates integrally with the mounting shaft 17 is fixed to the mounting shaft 17. A cooling fan 19a is provided on the upper surface of the peripheral edge of the fixed flange 19.

19a... are formed. Also, fixed flange I
A shallow recess 19b having a trapezoidal cross section is formed in the lower surface of the recess 9, and a through hole I9c through which the movable flange 20 having a convex cross section can pass is provided in the center of the recess 19b.

Further, reference numeral 21 denotes a disc-shaped grindstone, the peripheral edge of which protrudes forward in the axial direction, and a through hole 21a through which the upper part of the movable flange 20 can pass is provided in the center. and,
By fixing the movable flange 20 to the mounting shaft 17 with the bolts 22, the grindstone 21 is reliably held between the lower upper surface of the movable flange 20 and the lower surface of the peripheral edge of the fixed flange 19. Reference numeral 23 denotes a fan-shaped grindstone cover, the inner circumference of which is fixed to the lower end of the cylinder 11.

According to this configuration, since the casing 10 is made of glass fiber reinforced plastic, it is possible to improve the vibration damping properties due to the damping effect. That is,
As shown in the table, the top surface of the casing 10 (upper cover 12)
vibration can be suppressed to approximately 1/2. The table shows the experimental data, and compared to the case of light metal casing, 6.4G to 3.8G during no-load operation.
Furthermore, during grinding, the vibration acceleration can be reduced from 60G to 34G. In addition, G=9.8+n/s
! It is.

■Since it can have an electric double insulation structure, the casing 101. : Can prevent electricity from leaking.

[Effects of the Invention] As explained above, according to the present invention, there is provided a casing having a stator fixed to its inner circumferential surface, the stator...the rotor,
14a...Rotating shaft, 21...Whetstone.

An electric disc grinder 1 is equipped with a rotor that is rotationally driven within the rotor, and a grindstone that is directly connected to the rotating shaft of the rotor. As a result, the following effects can be achieved.

(1) Vibrations in the casing can be reduced by approximately half.

(2) Since glass fiber reinforced plastic is used as the casing material, an electrical double insulation structure can be realized without having to make the casing a double structure as in the conventional case.

(3) Since the casing is processed by injection molding, post-processing after molding is unnecessary, and costs can be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of an electric disc grinder according to an embodiment of the present invention, and FIG. 2 is a perspective view showing the conventional structure.

Claims (1)

[Claims] An electric disc grinder comprising a casing having a stator fixed to its inner peripheral surface, a rotor rotationally driven within the stator, and a grindstone directly connected to the rotating shaft of the rotor, wherein the casing is made of glass fiber reinforced plastic. An electric disc grinder characterized by being formed by.