JPS6125505B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention drives a vibration imparting mechanism built into a tool body by the air pressure of compressed air supplied through a grip attached to the tool body, Regarding a pneumatic grinding tool that performs grinding work by integrally applying vibration, it is particularly desirable to have a grip part that prevents vibrations applied to the tool body during grinding work from being transmitted to the hand through the grip part. This relates to anti-vibration structure.

BACKGROUND ART Conventionally, this type of pneumatic grinding tool has been widely used for grinding furniture or for polishing repaired parts of automobile bodies because of its ability to perform precise grinding work.

By the way, in the above-mentioned conventional tool, the tool body to which vibration is applied during grinding work and the grip part assembled to the main body for holding the main body by hand are connected via vibration-isolating rubber. However, the perfect anti-vibration effect has not always been achieved. Therefore, when gripping the grip part during grinding work, the gripping state of the grip part becomes unstable due to the vibration, and the force with which the grinding member is pressed against the surface of the workpiece to be ground becomes uneven. . As a result, the grinding state of the surface of the member to be ground, that is, the finished state, has a drawback.

Therefore, the present invention was proposed in order to eliminate the above-mentioned conventional drawbacks, and an object of the present invention is to prevent the vibrations from being transmitted to the hand through the grip section attached to the tool body during grinding work. shall be.

Another object of the present invention is to stabilize the vibration damping effect.

The gist of the present invention is a tool that includes a grip portion having an air supply passage communicating with a compressed air supply source, and a vibration imparting mechanism using the compressed air supplied through the air supply passage as a driving source. The air supply passage is arranged in an annular gap held between the main body, the grip part, and the tool body, and connects both the grip part and the tool body, and connects the air supply passage within the gap. an annular elastic member defining a communicating annular sealed chamber, one side of the elastic member having an opening side formed on one of the grip part side wall part or the tool body side wall part of the gap part narrow and facing the bottom. The elastic member is tightly fitted into an annular groove whose groove width gradually increases, and the other side of the elastic member is pressed into contact with either the side wall of the grip portion or the tool body side by the air pressure of compressed air supplied into the closed chamber. The closed chamber acts as an air damper to prevent vibrations of the tool body generated during operation from being transmitted to the grip portion.

Hereinafter, preferred embodiments of the present invention will be specifically described based on the drawings.

FIG. 1 is a longitudinal sectional side view showing one embodiment of the present invention.

The tool body 2 of this grinding tool 1 is formed to have a rectangular cross section. A cylindrical recess 3 is formed at the lower end of the main body 2, and by closing the recess 3 with a disc-shaped bottom cover 5 via an O-ring 4, the vibration imparting mechanism 6 is activated. A cylindrical drive chamber 7 is formed to which drive air is supplied. A bearing 10, which serves as the central axis of rotation of the rotor 9 of the unbalanced rotor 8 constituting the vibration imparting mechanism 6, is fixed at the center of the drive chamber 7 on the bottom cover 5 side so as to be integrated with the main body 2. It is fixed with screws 11.

The rotor 9 has an annular shape, and a prismatic vertical weight 12 is integrally fixed to a part of the outer periphery. The wall thickness of the vertical weight 12 is formed to be wider than the wall thickness of the rotor 9, and by increasing or decreasing the portions protruding from the upper and lower surfaces of the rotor 9, or by increasing or decreasing the wall thickness of the vertical weight 12. By increasing or decreasing the length of the rotor 9 in the circumferential direction, the weight of the vertical weight 12 can be adjusted. Note that this weight adjustment must be performed within a range where the upper and lower surfaces of the vertical weight 12 do not come into contact with the upper and lower surfaces of the drive chamber 7. Further, the outer end surface of the vertical weight 12 is curved in an arc shape so that it does not come into sliding contact with the peripheral wall surface 7A in the drive chamber 7 during rotation.

A first air supply passage 13 formed in the tool body 2 is formed in a part of the peripheral wall surface 7A of the drive chamber 7.
A drive air supply port 14 is provided which communicates with the drive air supply port 14 . On the other hand, a plurality of air discharge ports 70 are provided near the center of the bottom cover 5, and the discharged air discharged from the air discharge ports 70 is bonded to the bottom cover 5 and the lower end of the tool body 2. It is discharged into the atmosphere through a cylindrical muffling chamber 16 formed between the grinding member 54 and the mounting plate 15 and a small-diameter exhaust hole (not shown) bored in the tool body 2.

On the other hand, a cylindrical shape 17 serving as a grip support portion is bored in the center portion of the upper end of the tool body 2.
A cylindrical grip portion 18 for holding the main body 2 by hand is attached to this cylindrical body 17. The grip portion 18 includes a head portion 19 having a circular cross section, and a head portion 19 that protrudes around the lower end of the head portion 19 and extends toward the outer peripheral wall portion 21 of the cylindrical body 17 with a first annular gap portion 20 therebetween. A cylindrical holder part 22 to be assembled, and a second annular cavity 23 located inside the holder part 22 and protruding from the center of the lower end of the head part 19, with a second annular cavity 23 therebetween, and the cylindrical body 17. A cylindrical shaft portion 25 is assembled to the inner circumferential wall portion 24 side of the shaft portion.

First and second annular grooves 26 and 27 are formed in the outer peripheral wall 21 of the cylindrical body 17 within the first annular cavity 20 at a predetermined distance apart. Each of these grooves 26 and 27 has an opening 2 as shown in FIG.
The grooves are formed in a dovetail groove shape, which is narrow on the sides 6a and 27a and gradually increases in groove width toward the bottoms 26b and 27b.
Both end edges 28a and 28b of a thin first rubber material 28 serving as a first annular vibration-proofing elastic member are tightly fitted and held in each of these grooves 26 and 27. The rubber material 28 is bent to have a U-shape in longitudinal section so that an annular sealed chamber (first damper air chamber) 29 is formed inside, and the outer circumferential portion 28A is used to store the first damper air. The compressed air pressure supplied into the holder part 29 presses and engages the annular concave groove part 31 formed in the inner peripheral wall part 30 of the holder part 22.

On the other hand, each of the annular grooves 2 is also formed in the inner circumferential wall portion 24 of the cylindrical portion 17 within the second annular cavity 23.
A third annular groove 32 having the same shape as 6 and 27 is formed. In this annular groove 32, an outer peripheral edge 33a of a thin second annular rubber member 33 is tightly fitted and held. A positioning protrusion 34 having a through hole 35 is formed in the center of the rubber material 33, and this protrusion 34 is connected to a positioning recess 25b formed at the tip 25a of the shaft 25.
It is mated and retained. The second annular rubber member 33 is bent in an inverted U-shape in longitudinal section toward the outer peripheral edge 33a, and the second annular gap 2
3 is partitioned into two annular sealed chambers 36 and 37. One of the sealed chambers (second damper air chamber) 36 is in communication with the air conduction path 38 in the shaft portion 25, and the air chamber 36 is connected to the cylindrical body 17.
The damper air chamber 29 is in communication with the first damper air chamber 29 via a small diameter air passage 39.

During the grinding operation, the second damper air chamber 36 and the first damper air chamber 29 are filled with compressed air sent into the drive chamber 7 via the air conduction path 38.

In this way, the grip portion 18 and the tool body 2 are connected to each other during the grinding operation.
The first and second damper air chambers 29 and 36 are connected to each other via compressed air layers. Therefore, the vibrations caused by the operation of the vibration imparting mechanism 6 can be absorbed by the rubber materials 28, 33 and the compressed air layers, allowing stable grinding work to be performed. Further, even if the direction of vibration generated in the tool body 2 is not only horizontal but also vertical to the grip portion 18, this vibration can be sufficiently absorbed.

Moreover, the edge 28a of each of the above-mentioned rubber members 28, 33,
28b, 33a are dovetail groove-shaped annular grooves 26, 2.
7 and 32, the assembly is reliable and there is no air leakage.
8 and 33 and supplying the compression core to the first and second damper air chambers 29 and 36, the vibration damping effect becomes stable.

On the other hand, a second air supply passage 40 is formed in the head part 19 of the grip part 18, and serves as a compression core supply passage to the damper air chambers 29, 36 and the drive chamber 7 of the vibration applying mechanism 6. There is. This air supply passage 40 is connected to the air conduction passage 38 in the shaft portion 25 via an on-off switching valve 41. That is, the second air supply passage 4
0 is the above-mentioned on-off switching valve 41 and the above-mentioned air conduction path 3
8 and the second damper air chamber 36 to the first air supply passage 13 formed in the main body 2.

The opening/closing switching valve 41 is a valve piston 41.
A and a valve cylinder 41B into which the piston 41A is slidably and tightly fitted, and the valve piston 41A has an opening/closing piston part 43 fitted with an O-ring 42 on one end side, and a valve cylinder 41B on the other end side. It has an operating piston part 44 at the top thereof, and these piston parts 43 and 44 are connected by a joint stem part 45.

The entire valve piston 41A is operated by pressing the operating lever 47, which has a fan-shaped cross section and engages with the hemispherical protrusion 46 provided at the end of the operating piston portion 44. A sliding operation is performed in the A direction. Then, the opening/closing piston section 43 opens between the second air supply passage 40 and the air conduction passage 38, and inserts the air plug 48 screwed into the opening 40a of the second air supply passage 40. The compressed air supplied into the air supply passage 40 through the air supply passage 38 , the second damper air chamber 36 , and the first air supply passage 13
It is supplied into the drive chamber 7 via.

When the pressing operation of the operating lever 47 is released, the entire valve piston 41A is activated by the compressed air pressure acting on the end face of the opening/closing piston section 43 and by the compressed coil spring disposed in the second air supply passage 40. 1st due to the resilience of 49
By sliding in the direction of arrow B in the figure, the opening/closing piston portion 43 closes the space between the second air supply passage 40 and the air conduction passage 38, and the supply of compressed air into the drive chamber 7 is cut off. It can be done.

On the other hand, the operating lever 47 is connected to the head portion 19.
It is held by a support pin 51 that is inserted and supported so as to vertically pass through an opening 50 opened at .

Further, the operating lever 47 is provided with a locking mechanism 52 for holding the lever 47 in a pressed state.

Also, the mounting plate 1 is attached to the lower end of the tool body 2.
A protective member 53 that serves as a cushion material is fixed to 5.
A grinding member 54 such as sandpaper is attached via a clamp device 55.

The grip portion 18 also includes a head portion 19;
A vibration absorbing member 56 made of a soft material such as rubber, sponge, or foam material is attached to cover the outer surface of the holder portion 22 and the entire air plug.

FIG. 3 is a longitudinal sectional side view of main parts showing another embodiment of the present invention. In this embodiment, the same reference numerals are given to the parts having the same configuration as those in the above embodiment, and detailed explanation thereof will be omitted. In this example,
The center portion is the tip 25 of the shaft portion 25 of the grip portion 18.
In a, a thin annular anti-vibration rubber material 57 which is positioned and held in a similar manner to the previous embodiment extends along the outer circumferential wall 25A of the shaft portion 25 and the inner circumferential wall 30 of the holder portion 22. The outer peripheral edge 57a side is bent inward, and the edge 57a side is bent inwardly.
7a is tightly fitted and held in an annular groove 58 formed in the outer peripheral wall portion 21 of the cylindrical body 17 of the tool body 2. The annular groove 58 is formed in a dovetail groove shape, which is narrow on the opening 58a side and gradually increases in groove width toward the bottom 58b, as in the previous embodiment. The bent portion 59 formed on the outer peripheral edge 57a side of the rubber material 57 is an annular step portion 6 formed on the inner peripheral wall portion 30 of the holder portion 22.
0 is press-fitted.

In the embodiment having the above configuration, the first air supply passage 13 is
The compressed air sent into the first and second annular gaps 20 and 2 sealed by the rubber material 57
3, and each of these voids 20 and 23 becomes a damper air chamber 61 filled with compressed air.
Therefore, vibrations in all directions generated within the tool body 2 during grinding work can be absorbed by the compressed air layer in the rubber material 57 and the damper air chamber 61, and the grip portion 18 is held. Grinding work can be performed stably without any vibration being applied to the hands.

As is clear from the above description, according to the present invention, it is possible to prevent vibrations applied to the tool body during grinding work from being transmitted to the grip part, and the grip part is always held with a constant force during grinding work. can be done. Therefore, the force with which the grinding surface of the grinding member is pressed against the surface to be ground can also be kept constant, so that the surface to be ground can be ground uniformly.

Further, according to the present invention, the sealing state of the damper air chamber that performs the vibration-proofing effect can be ensured, and the vibration-proofing effect can be stabilized.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional side view showing an embodiment of the present invention;
FIG. 2 is an enlarged vertical cross-sectional side view showing a connecting portion between the grip portion and the tool body, and FIG. 3 is a vertical cross-sectional side view of main parts showing another embodiment of the present invention. 1...Pneumatic grinding tool, 2...Tool body, 6
... Vibration imparting mechanism, 13, 40... Air supply passage, 18... Grip portion, 20... First annular cavity, 23... Second annular cavity, 26, 2
7, 32... Annular groove, 28, 33, 57... Annular vibration-proofing rubber material, 29, 36, 61... Air chamber for damper, 38... Air conduction path.

Claims (1)

[Claims] 1. A grip section having an air supply passage communicating with a compressed air supply source, a tool body equipped with a vibration imparting mechanism whose drive source is compressed air supplied via the air supply passage, the grip section and the upper tool. An annular airtight chamber is disposed within an annular cavity held between the tool body and connects the grip part and the tool body, and the cavity is divided into an annular sealed chamber that communicates with the air supply passage. one side of the resilient member is an annular groove formed on one of the side wall of the grip portion or the side wall of the tool body of the cavity, the opening side of which is narrow and the groove width gradually increasing toward the bottom; At the same time, the other side of the elastic member is press-fitted to either the side wall of the grip portion or the tool body by the air pressure of compressed air supplied into the sealed chamber, thereby closing the sealed chamber. 1. A pneumatic grinding tool, characterized in that the elastic member acts as an air damper to provide support in at least the radial direction, and further, the elastic member supports the grip portion and the tool body so as to be movable in the vertical direction.