EP0333933A1

EP0333933A1 - Sanding apparatus

Info

Publication number: EP0333933A1
Application number: EP88200524A
Authority: EP
Inventors: Yasuzi Hirahara
Original assignee: Maeda Kiko Co Ltd
Current assignee: Maeda Kiko Co Ltd
Priority date: 1988-03-22
Filing date: 1988-03-22
Publication date: 1989-09-27
Anticipated expiration: 2008-03-22
Also published as: EP0333933B1; DE3884187T2; DE3884187D1

Abstract

A sanding apparatus (10, 10a) is characterised by a plate member (13) provided with a sanding member (26) on one surface thereof which fronts a surface to be sanded and with a locking projection (17) on the other surface thereof, a body (11) having a locking hole (16) for loosely receiving the locking projection (17), a drive shaft (12) housed in the body (11) and rotatable on an axis perpendicular to an abrasive surface of the sanding member (26), a driving power source (40) for energizing the drive shaft (12) which is housed in the body (11), a peripheral cam (19) fixed to the drive shaft (12), and a follower (20) fixed to the plate member (13) and rotatable in abutment with a cam face of the peripheral cam, the follower (20) having a center of rotation eccentric relative to the center of rotation of the drive shaft (12).

Description

This invention relates to a sanding apparatus suitable for use in sanding a painted surface of, for example, an auto body.
Fig. 1 is a perspective view showing a typical prior art. The prior art sanding apparatus 1 includes a body 2 having a drive power source 3, a drive shaft 6 housed in the body 2, and a mounting plate 4 for mounting thereon an abrasive member 5, such as a sandpaper. The drive shaft 6 in the body 2 is connected at one end to the drive power source 3, and at the other end 6a of the drive shaft 6 the mounting plate 4 is threadedly secured by a mounting screw not shown. A bearing not shown is mounted to the end 6a of the drive shaft 6 at the mounting plate 4 side and on the center of rotation of the drive shaft 6 in eccentric relation therewith, said bearing being in thread engagement with said mounting screw.
The mounting plate 4 is comprised of a rectangular plate material and has a mounting surface perpendicular to the axis of the drive shaft 6 on the opposite side from the body 2 (i.e., on the front side toward a surface to be sanded), the abrasive member 5, e.g., sand paper, being removably mounted with an adhesive on said mounting surface. On the other side of the mounting plate 4 which faces the body 2 and at four corners thereof there are disposed column shaped projections 7 formed of a resilient material, such as rubber, the free ends of the projections 7 being secured to the body 2. By this arrangement the mounting plate 4 is prevented from rotating in conjunction with the drive shaft 6 when driven by the drive power source 3, but because of the bearing mounted on the center of rotation of the drive shaft 6 in eccentric relation therewith, the mounting plate 4 is allowed to perform circular movement. Through this circular movement of the mounting plate 4, the abrasive member 5 mounted on the mounting plate 4 makes circular movement.
According to the above described prior art arrangement, the mounting plate 4 makes circular movement to sand a coated surface or the like. Therefore, if any difference in level, such as protuberance, is present on the coated surface, a side of the mounting plate 4 strikes on a side of the protuberance intermittently and thus the surface cannot be fully sanded at positions adjacent the base of the protuberance. If the sanding apparatus 1 is forcefully pressed against the surface to give greater sanding effect, the resistance of the abrasive member 5 is increased, so that greater vibration is felt by the operator holding the sanding apparatus 1, with the result of decreased efficiency.
Accordingly it is an object of the invention to provide an improved sanding apparatus.
It is another object of the invention to provide a sanding apparatus which eliminates aforesaid technical difficulties and which can thus perform sanding easily and at improved efficiency with respect to all surfaces requiring to be sanded.
To achieve the above and other objects, a sanding apparatus according to the invention is characterised by a plate member provided with a sanding member on one surface thereof which fronts a surface to be sanded and with a locking projection on the other surface thereof, a body having a locking hole for loosely receiving the locking projection, a drive shaft housed in the body and rotatable on an axis perpendicular to an abrasive surface of the sanding member, a driving power source for energizing the drive shaft which is housed in the body, a peripheral cam fixed to the drive shaft, and a follower fixed to the plate member and rotatable in abutment with a cam face of the peripheral cam, the follower having a center of rotation eccentric relative to the center of rotation of the drive shaft.
In a preferred embodiment, the locking projection is made of resilient material.
In another preferred embodiment, the section rectangular to the axis of the locking hole forms a circle or at least an enclosed curve which is convex outward in the radial direction all over the periphery of the locking hole.
In a further preferred embodiment, the follower is fixed between the front end portion of the plate member and the locking projection.
In a still further preferred embodiment, the locking projection is provided between the front end portion of the plate member and the position of the follower which is fixed to the plate member.
Further, to achieve the above and other objects, a sanding apparatus according to the invention is characterised by a plate member provided with a sanding member on one surface thereof which fronts a surface to be sanded and with a locking concave portion on the other surface thereof, a connection member formed with a locking portion to be locked on the locking concave portion of the plate member, a body being removably attached to the connection member, a peripheral cam housed in the body and rotated on a rotating axis by a driving power source, a follower fixed to the connection member, rotatable in abutment with a cam face of the peripheral cam, and having a center of rotation eccentric retative to the center of rotation of the peripheral cam, and a rotary motion blocking means fixed to the connection member and having an axis parallel to the axis of the peripheral cam.
In a preferred embodiment, the plate member is removably attached to the connection member.
In another preferred embodiment, the rotary motion blocking means includes an outer cylinder member being shaped in a right circular cylinder and fixed to the body, and a core member having a smaller outer diameter than an inner diameter of the outer cylinder member and housed into the outer cylinder member, the core member being displaceable in such a state that the core member is housed in the outer cylinder member.
In a still another preferred embodiment, the core member is made of resilient material.
In a further preferred embodiment, the driving power source is a pneuamtic motor.
In a still further preferred embodiment, the body is provided with a handle having an axis perpendicular to the axis of the body and in the free end portion of the handle, there is mounted a joint port for supplying compressed air to the driving power source and a discharge port for exhausting air from the driving power source.
According to the invention, the plate member provided with a sanding member has a locking projection which loosely fits in a locking hole provided in the body of the sanding apparatus. A follower is fixed to the plate member, the rotational center of the follower being eccentric relative to the center of rotation of the drive shaft. Therefore, the plate member, pivotally supported on the locking projection, is caused to reciprocate generally as the drive shaft rotates, whereby sanding is performed with respect to the surface to be sanded. Further, according to the arrangement of the invention, the velocity of the movement of the plate member at a point adjacent the sanding member thereon is faster than the velocity of the reciprocating motion of the rotation center of the follower. In addition, since the locking projection loosely fits in the locking hole, no appreciable vibration is likely to be applied to the operator even if the body of the sanding apparatus is firmly pressed against the surface being sanded, which means easy operation of sanding and improved operating efficiency.
These and other objects, features, and advantages of the invention will become more apparent from a reading of the following detailed description taken in connection with the accompanying drawings, in which:

Fig. 1 is a perspective view showing a typical prior art arrangement;
Fig. 2 is an exploded perspective view showing a sanding apparatus 10 representing one embodiment of the present invention;
Fig. 3 is a view illustrative of operation of a mounting plate 13;
Fig. 4 is a view of the mounting plate 13 as seen when an obstacle is present alongside the plate 13;
Fig. 5 is a view showing a trajectory of the front end A of sanding member 26 of the mounting plate 13 as seen in the longitudinal direction of the mounting plate 13 in Figs. 3 and 4;
Fig. 6 is a perspective view of a locking hole 35 of another embodiment of the sanding apparatus according to the invention;
Fig. 7 is a schematic view showing trajectories of the front end A of the sanding member 26 on the mounting plate 26 as seen in the longitudinal direction of the mounting plate 13, when the locking hole 35 is oriented in two different directions;
Fig. 8 is an exploded perspective view of a sanding apparatus 10a representing another embodiment;
Fig. 9 is a perspective view of a sanding apparatus 10b representing a still another embodiment of the invention;
Fig. 10 is an exploded perspective view thereof;
Fig. 11 is a perspective view showing a pipe joint 73 mounted to a handle 52 and adjacent parts;
Fig. 12 is a perspective view showing a mounting plate 71a as seen when it is disengaged from a connecting piece 70;
Fig. 13 is a section taken on line XIII - XIII in Fig. 12;
Fig. 14 is a perspective view showing a mounting plate 71b in another embodiment for being mounted to the sanding apparatus 10b; and
Fig. 15 is a perspective view showing a mounting plate 71c in a still another embodiment for being mounted to the sanding apparatus 10b.

Preferred embodiments of the invention will now be described in detail with reference to the drawings.
Fig. 2 is an exploded perspective view of a sanding apparatus 10 representing one embodiment of the invention. Referring to Fig. 2, the sanding apparatus 10 includes a body 11 to be held by the operator during a sanding operation, a drive shaft 12 housed in the body 11, and a mounting plate 13 mounted to the drive shaft 12.
The body 11 is generally L-shaped and has a drive power source 40, such as a motor- or compressed air-powered rotor. The body 11 has at one lengthwise end thereof a mounting hole 14 having an axis perpendicular to the longitudinal direction of the body 11, and the drive shaft 12 which will be further described hereinafter is housed in the mounting hole 14 in coaxial relation therewith. The housed drive shaft 12 is connected to said drive power source 40 by which it is driven to rotate. An electric cord or air pipe for the drive power source 40 is connected to the other end of the body 11.
The body 11 also has a cylindrical locking hole 16 which constitutes a rotary motion blocking means 15 for blocking the rotation of the mounting plate 13 which will be further described hereinafter. The axis of the locking hole 16 is perpendicular to the longitudinal direction of the body 11 and parallel to the axis of the mounting hole 14, said locking hole 16 being open codirectionally with the mounting hole 14 and at a position more adjacent the lengthwise directional center of the body 11 than the location of the mounting hole 14. The locking hole 16 receives thereinto a locking projection 17, another constituent of said rotary motion blocking means 15, which will be described hereinafter.
As above mentioned, the drive shaft 12 is connected to the drive power source 40 at its one end at which it is inserted in the body 11. At the other end of the drive shaft 12 there is integrally formed a mounting member 18 in coaxial relation with the drive shaft 12. The mounting member 18 has a mounting hole 19 formed as a peripheral cam for mounting a bearing 20 as a follower, the axis of said mounting hole 19 being parallel to the axis of the drive shaft 12 in eccentric relation therewith. The bearing 20 is internally threaded at it center to form a threaded hole 21 into which the mounting plate 13 to be hereinafter further described is threadly fitted by a bolt 22.
The mounting plate 13 comprises a base plate 23 made of a metal material shaped in a plate, a resilient member 24 made of sponge, rubber or the like which is fixed to one side of the base plate 23, and a surface member 25 comprised of, for example, synthetic leather, which is fixedly placed on the resilient member 24. An abrasive member 26, such as sandpaper, if removably mounted with an adhesive on the surface member 25. The resilient member 24 mounted on the base plate 23 permits the abrasive member 26 to adapt itself for the configuration of the surface being sanded, so that uniform sanding can be effectively performed. Further, the surface member 25 of synthetic leather or the like permits easy removal of the abrasive member 26 from the surface member 25 and accordingly easy replacement of the abrasive member 26. At a lengthwise directional center location on the mounting plate 13 having the resilient member 24 and the surface member 25 placed in layers, there is formed an embedding hole 27 for embedding therein the head of the bolt 22 for securing the mounting plate 13 in the bearing 20, whereby the surface to be sanded is prevented from being damaged by the bolt head in the course of a sanding operation. Further, an insertion hole 29 for the bolt 22 is provided in the base plate 23 at a lengthwise directional center portion thereof.
On the other side surface of the base plate 23 of the mounting plate 13, the locking projection 17 as one constituent of the rotary motion blocking means 15 for blocking the rotation of the mounting plate 13 is fixed in position perpendicularly to the lengthwise direction of the base plate 23. The locking projection 17 is formed of a resilient material, such as hard rubber or the like, and is generally column shaped. On the free end side top of the locking projection 17 there is fixed a metal made thin plate 28 of disc shape, whereby the free end portion of said locking projection 17 as inserted in said locking hole 16 is prevented from being damage during operation of the sanding apparatus 10. As already mentioned, the rotation of the mounting plate 13 is prevented by the locking projection 17 being inserted into the locking hole 16, and in this conjunction it is noted that the inner diameter ℓ1 of the locking hole 16 is set larger than the inner diameter ℓ2 of the locking projection 17, there being still provided some degree of play. By virtue of the above described arrangement, the mounting plate 13 is mounted so that the mounting plate 13 and the body 11 are positioned parallel in their lengthwise direction.
Fig. 3 is a view illustrating the manner of operation of the mounting plate 13, Fig. 4 is a view showing the mounting plate 13 as seen when an obstacle 30 is present alongside the plate 13, and Fig. 5 is a schematic view showing a trajectory of the front end A of the abrasive member 26 mounted portion of the mounting plate 13 as seen in the longitudinal direction of the mounting plate 13. The manner of operation of the sanding apparatus 10 will be explained with reference to Figs. 2 through 5.
The drive shaft 12 is driven to rotate by the drive power source 40. Similarly, the mounting member 18 and the bearing 20, and the mounting plate 13 threadedly supported in the bearing 20 are also driven to so rotate. However, it must be noted that the locking projection 17 is fixed to the mounting plate 13 and that the free end o-F said projection 17 is inserted in the locking hole 16; therefore, the rotation of the mounting plate 13 is prevented. The mounting plate 13 prevented from rotating by the rotary motion blocking means 15 consisting of the locking hole 16 and the locking projection 17 is caused to perform reciprocating movement in a general sense of the word while being pivotally supported on the locking projection 17, because the axis of the bearing 20 is eccentric relative to the axis of the drive shaft 12.
In conjunction with the above described reciprocating motion, it is noted that on a line F passing the centers of the locking projection 17 and the insertion hole 29 in the base plate 23, the distance P3 over which the front end point A of the mounting plate 13 is driven to reciprocate can be made twofold the distance P4 over which the center of the bearing 20 is driven to reciprocate, by equalizing the distance P1 of from the lengthwise directional front end point A of the mounting plate 13 to the center of the insertion hole 29 with the distance P2 of from the center of the insertion hole 29 to the center of the locking projection 17 which serves as a pivotal point, so that the surface area of reach of the mounting plate 13 for sanding operation can be increase. The speed of reciprocation of the front end point A of the mounting plate 13 is also increased to two times as high as that of the center of the bearing 20, and accordingly improved operating efficiency is obtained. In this case, the trajectory of the front end point A of the mounting plate 13 is of a generally ellipsoidal configuration, in which the major axis is perpendicular to the longitudinal direction of the mounting plate 13, as shown by a two dot chain line B in Fig. 5.
In the present embodiment, the mounting plate 13 is driven to reciprocate, but as Fig. 4 shows, if an obstacle 30 projecting from the surface being sanded is present on one side of the mounting plate 13, the reciprocating movement of the mounting plate 13 in a direction perpendicular to the longitudinal direction thereof is limited at a location adjacent the lengthwise directional front end A of the mounting plate 13. Accordingly, the reciprocating movement of the mounting plate 13 at a location adjacent its front end A is of a generally ellipsoidal pattern such that the major axis of the ellipsoid extends along the longitudinal direction of the mounting plate 13, as shown by a two dot chain line B in Fig. 4.
The manner of operation in this case will be explained. As Fig. 4 shows, if one side of the mounting plate 13 abuts an unremovable obstacle 30 in the course of sanding operation with respect to a surface to be sanded, any further reciprocating movement of the mounting plate 13 in a direction perpendicular to the longitudinal direction of thereof is prevented. Although the movement toward the obstacle 30 of the mounting plate 13 at its lengthwise directional end is prevented, the end of the mounting plate 13 is pivotally displaced at contact point G and on the side at which the locking projection 17 is fixed to the mounting plate 13, in a direction away from the obstacle 30. This displacement in a direction away from the obstacle 30 is possible because there is provided a play between the locking projection 17 and the locking hole 16. Further, the fact that the locking projection 17 is made of resilient material permits a greater degree of displacement away from the obstacle 30 than the play permits, through the deformation of the locking projection 17. Accordingly, as shown by a two dot chain line C in Fig. 5, the trajectory of the longitudinal directional front end A of the mounting plate 13 is of such pattern of reciprocating movement as is oriented in the longitudinal directions of the mounting plate 13 while lateral directional movement is prevented, as compared with the primary trajectory of the sanding apparatus 10 in the present embodiment (as shown by the two dot chain line B in Fig. 5). Therefore, the surface to be sanded can be satisfactorily sanded even in the vicinity of the base end portion of the obstacle 30.
Further, even if the sanding apparatus 10 is forcefully pressed against the surface to be sanded in order to obtain a higher degree of sanding, the play provided between the locking projection 17 and the locking hole 16, coupled with the fact that the locking projection 17 is deformable because it is comprised with a resilient material, much of the vibration caused is absorbed by the locking projection 17 so that the vibration which may be otherwise transmitted to the operator is considerably reduced, it being thus possible for the operator to carry out sanding operation easily and more efficiently.
Fig. 6 is a perspective view showing a locking hole 35 in a sanding apparatus representing another embodiment of the invention. In the above described embodiment, the locking hole 16 is cylindrical, but the locking hole 35 in this Fig. 6 embodiment is, as shown, generally oval shaped in its section rectangular to the axis thereof, that is, of such configuration having two parallel flat portions and arcuate portions formed at both ends of the parallel flat portions. The locking hole 35 is rotatable about its axis so that it may be longitudinally oriented in any desired direction.
Fig. 7 is a view showing trajectories of the lengthwise directional front end A of the mounting plate 13 as seen when the longitudinal position of the locking hole 35 is varied in two ways. As Fig. 7 (1) shows, for example, where the locking hole 35 is positioned longitudinally parallel to the body 11 of the sanding apparatus 10, the movement of the locking projection 17 in a direction perpendicular to the longitudinal direction of the locking hole 35 is prevented but it is movable in the longitudinal direction of the locking hole 35. Therefore, the trajectory of the front end A of the mounting plate 13 represents a generally elliptic pattern of movement as shown by a two dot chain line D in Fig. 7 (1) wherein the distance of movement of the mounting plate 13 in its longitudinal direction is equal to the diameter of the trajectory of rotary movement of the center of the bearing 20, whereas the distance of movement of the mounting plate 13 in a direction perpendicular to its longitudinal direction is about two times said diameter. Where the locking hole 35 is longitudinal perpendicular to the longitudinal direction of the body 11, as Fig. 7 (2) shows, the trajectory of said front end A represents such a generally elliptic pattern as shown by a two dot chain line E in Fig. 7 (2), similarly to the above case, so that the movement of the mounting plate 13 can be changed simply by changing the longitudinal position of the locking hole 35. Therefore, it is possible to select such movement of the mounting plate 13 as is most suitable with respect to the surface to be sanded, by changing the longitudinal direction of the locking hole 35, thus enabling the operator to perform sandning operation at ease and assuring improved operating efficiency.
In the above described embodiment, the locking hole 35 has parallel portions and a generally oval shaped section perpendicular to its axis, but the section perpendicular to the axis may be of a generally ellipic configuration.
Fig. 8 is an exploded perspective view of a sanding apparatus 10a representing a still another embodiment of the invention. In this embodiment, parts similar or corresponding to those in the above described embodiments are designated by the like reference numerals or characters. In each of the preceding embodiments, the locking hole 16 is disposed more adjacent to a median position than the mounting hole 14 as viewed in the longitudinal direction of the body 11, but in this embodiment the locking hole 16 is disposed adjacent but outwardly (rightward in Fig. 8) of the mounting hole 14 in the longitudinal direction of the body 11.
The mounting plate 13 has a locking projection 17 formed centrally in the longitudinal direction thereof and on the base plate 23 side, said mounting plate 13 being fitted into said locking hole 16. At a location adjacent one lengthwise directional side of the mounting plate 13 there is formed a threaded hole 29 which is threadedly fixed to the bearing 20 by the bolt 22.
According to such arrangement, as is the case with the first embodiment, the mounting plate 13 can perform reciprocating movement in the longitudinal direction thereof if any unremovable obstacle 30 is present on the surface to be sanded.
Fig. 9 is a perspective view showing a sanding apparatus 10b representing still another embodiment of the invention and Fig. 10 is an exploded perspective view thereof. The sanding apparatus 10b of this embodiment comprises a body 51, and a longitudinal rod like handle 52 connected to the body 51. The body 51 has a generally right circular cylinder shaped first body portion 53 and a second body portion 54 formed integrally with the first body portion 53. The first body portion 53 has a housing hole 55 defined therein which extends through said body portion 53 in the axial direction thereof, a pneumatic motor being housed in said hole 55. One end side opening of the housing hole 55 is closed by a cover member 56 fixed to the first body portion 53. A mounting member 57 is connected to a drive shaft extending from the pneumatic motor, said mounting member 57 being rotatable about the rotation axis thereof. The mounting member 57 has a mounting hole 58 having an axis eccentric to its rotation axis, a bearing 59 being housed in the mounting hole 58. The bearing 59 has an internally threaded hole 60.
The second body portion 54 has a housing hole 61 continuted to the housing hole 55 of the first body portion 53, there being housed rotary movement blocking means 62 in said housing hole 61. The rotary movement blocking means 62 include a right circular cylinder shaped outer cylinder member 63 comprised of a resilient material, such as rubber, and a column shaped core member 64 having a slightly smaller outer diameter than the inner diameter of the outer cylinder member 63. The core member 64 is comprised of same material as the outer cylinder member 63, its base portion being fixed to the second body portion 54. A screw rod 65 having an externally threaded periphery is fixed to the free end of the core member 64, said rod 65 extending outwardly from the outer cylinder member 63. A connecting piece 70 is removably mounted to said body 61, and on the connecting piece 70 there is fitted a mounting plate 71a.
A cover 72 having a generally right circular cylinder shape is fitted on the handle 52 connected to the body 51. The cover 72 is made of such material as rubber or synthetic resin. The handle 52 is provided, at its free end side, with a pipe joint 73, as Fig. 11 shows, so that an end connection extending from a pressure source not shown is connected to said joint 73 to supply compressed air to a pneumatic motor provided in said first body portion 53, whereby the apparatus can be driven. The compressed air supplied through this pipe joint 73 is fed to the pneumatic motor in the first body portion 53 when a control piece 74 projecting from the outer perphery of the handle 52 is depressed in the direction of arrow M in Fig. 10. Exhaust air from the pneumatic motor is evacuated from a discharge port 66. Unless the control piece 74 is depressed in the direction of arrow M, the compressed air supplied through the pipe joint 73 is blocked and therefore the pneumatic motor in the first body portion 53 is in standing condition.
Referring again to Fig. 10, said connecting piece 70 has a flat plate-form base portion 75 and a mounting portion 76 continued from the base portion 75. The base portion 75 is formed with insertion holes 77, 78 extending in the width direction thereof. In the insertion hole 77 is fitted said screw rod 65 of the rotary movement blocking means 62, with a washer 79 fitted on the screw rod 65, a nut 80 being then threadedly fitted thereon. In this way the connecting piece 70 is mounted on the screw rod 65. When this condition is reached, the insertion hole 78 is in communication with the threaded hole 60 of the bearing 59.
The mounting plate 71a is mounted on the connecting piece 70 thus placed in position. The mounting hole 71a has a base portion 81 and a mounting portion 82 continued to one lengthwise directional end of the base portion 81. The base portion 81 is provided with opposed guide pieces 83, 84, each having an inverted L shape. The mounting portion 82 is formed at its free end with an insertion hole 85. Therefore, as Fig. 12 shows, the connecting piece 70 as mounted to the body 51 is combined into unity with the mounting plate 71a in such a way that a pair of flanges 88, 89 formed in the mounting portion 76 of the connecting piece 70 are fitted in along guide grooves 88, 89 of the guide pieces 83, 84, a bolt 91 with a washer 90 fitted thereon is fitted through an insertion hole 85 and further through the insertion hole 78 into the threaded hole 60 of the bearing 59 for thread engagement. Thus, the mounting plate 71a, together with the connecting rod 70, is fixed to the body 51.
Fig. 13 is a section taken on line XIII - XIII in Fig. 12. On that side of the base portion 81 of the mounting plate 71a which is opposite to the side on which said guide pieces 83, 84 are formed there is fixed a resilient member 92, on the surface of which a surface member 93 is fixed. An abrasive member 94 is removably mounted with an adhesive or the like on the surface of the surface member 93. The resilient member 92 is made of an elastic material, such as sponge or rubber, and the surface member 93 is comprised of, for example, synthetic rubber. For the abrasive member 94, sand paper is used, for example.
In the above described sanding apparatus 10b, the mounting plate 71a is replaceably mounted to the connecting piece 70. Therefore, the mounting plate 71a may be removed from the connecting piece 70 and another mounting plate 71b as shown in Fig. 14 may be mounted to the connecting piece 70. Alternatively, a still another mounting plate 71c as shown in Fig. 15 may be mounted to the connecting piece 70. Further, if desired, any other suitable mounting plate that 71a - 71c may be mounted to the connecting piece 70.
Therefore, where such sanding apparatus 10b as above described, in which mounting plates 71a - 71c and other mounting plates can be replaceably used according to the configuration of the surface to be sanded, improved efficiency of sanding operation and improved quality of sanded surfaces can be obtained.

Claims

1. A sanding apparatus (10,10a) characterised by:
a plate member (13) provided with a sanding member (26) on one surface thereof which fronts a surface to be sanded and with a locking projection (17) on the other surface thereof,
a body (11) having a locking hole (16) for loosely receiving the locking projection (17),
a drive shaft (12) housed in the body (11) and rotatable on an axis perpendicular to an abrasive surface of the sanding member (26),
a driving power source (40) for energizing the drive shaft (12) which is housed in the body (11),
a peripheral cam (19) fixed to the drive shaft (12), and
a follower (20) fixed to the plate member (13) and rotatable in abutment with a cam face of the peripheral cam, the follower (20) having a center of rotation eccentric relative to the center of rotation of the drive shaft (12).

2. A sanding apparatus (10, 10a) as claimed in claim 1, wherein the locking projection (17) is made of resilient material.

3. A sanding apparatus (10, 10a) as claimed in claim 1, wherein the section rectangular to the axis of the locking hole (16) forms a circle or at least an enclosed curve which is convex outward in the radial direction all over the periphery of the locking hole (16).

4. A sanding apparatus (10, 10a) as claimed in claim 1, wherein the follower (20) is fixed between the front end portion (A) of the plate member (13) and the locking projection (17).

5. A sanding apparatus (10, 10a) as claimed in claim 1, wherein the locking projection (17) is provided between the front end portion (A) of the plate member (13) and the position of the follower (20) which is fixed to the plate member (13).

6. A sanding apparatus (10b) characterised by:
a plate member (71a,71b,71c) provided with a sanding member (94) on one surface thereof which fronts a surface to be sanded and with a locking concave portion (88, 89) on the other surface thereof,
a connection member (70) formed with a locking portion (86, 87) to be locked on the locking concave portion (88, 89) of the plate member (71a, 71b, 71c),
a body (51) being removably attached to the connection member (70),
a peripheral cam (57) housed in the body (51) and rotated on a rotating axis by a driving power source,
a follower (59) fixed to the connection member (70), rotatable in abutment with a cam face (58) of the peripheral cam (57), and having a center of rotation eccentric retative to the center of rotation of the peripheral cam (57), and
rotary motion blocking means (62) fixed to the connection member (70) and having an axis parallel to the axis of the peripheral cam (57).

7. A sanding apparatus (10b) as claimed in claim 6, wherein the plate member (71a, 71b, 71c) is removably attached to the connection member (70).

8. A sanding apparatus (10b) as claimed in claim 6, wherein the rotary motion blocking means (62) includes an outer cylinder member (63) being shaped in a right circular cylinder and fixed to the body (51), and a core member (64) having a smaller outer diameter than an inner diameter of the outer cylinder member (63) and housed into the outer cylinder member (63), the core member being displaceable in such a state that the core member (64) is housed in the outer cylinder member (63).

9. A sanding apparatus (10b) as claimed in claim 6, wherein the core member (64) is made of resilient material.

10. A sanding apparatus (10b) as claimed in claim 6, wherein the driving power source is a pneuamtic motor.

11. A sanding apparatus (10b) as claimed in claim 6, wherein the body (51) is provided with a handle (52) having an axis perpendicular to the axis of the body (51) and in the free end portion of the handle (52), there are mounted a joint port (73) for supplying compressed air to the driving power source and a discharge port (66) for exhausting air from the driving power source.