AU707002B2

AU707002B2 - Apparatus for clamping sanding sheet for sander

Info

Publication number: AU707002B2
Application number: AU52998/98A
Authority: AU
Inventors: Shinji Ogawa
Original assignee: Ryobi Ltd
Current assignee: Ryobi Ltd
Priority date: 1997-02-07
Filing date: 1998-02-06
Publication date: 1999-07-01
Anticipated expiration: 2018-02-06
Also published as: FR2759312A1; FR2759312B1; JPH10217134A; JP3263333B2; AU5299898A

Description

Such apparatus for clamping the sanding sheet are disclosed for example in Japanese Patent Publication No. S60-3546, Japanese Utility Model Provisional Publication No. S57-13148, Japanese Utility Model Provisional Publication No. S58-80155, Japanese Utility Model Provisional 6 Publication No. H1-170565, Japanese Utility Model Publication No. H4-13080 and Japanese Utility Model Publication No. S53-20796.

However, in the clamping apparatus disclosed in Japanese Patent Publication No. S60-3546 and Japanese Utility Model Provisional Publication No. H1-170565, an operation lever for causing the clamp member to be 0l operated, by which the sanding sheet is clamped projects upward from the housing of the sander. Due to such a construction, the length of the operation lever is compelled to be shorten so that the operation lever is not obstructive to the working operation of the sander, and a larger force is therefore required for operating the operation lever against a resilient force of /6 a spring associated with the clamp member, thus resulting in difficulty in .i operation of the operation lever. When the clamp member is restored to the eclosing condition, the operation lever is returned suddenly by means of the spring associated with the clamp member, thus causing problems in safety.

In the clamping apparatus disclosed in Japanese Utility Model Provisional Publication No. S57-13148, an arm provided on the one end of a coil spring for imparting the clamping force to the clamp member is swingable between a closing position and an opening position on the oscillation plate.

Due to such a construction, the length of the above-mentioned arm is compelled to be shorten, and a larger force is therefore required for swinging Q the arm from the opening position to the closing position, thus resulting in difficulty in operation of the arm.

In the clamping apparatus disclosed in Japanese Utility Model Provisional Publication No. S58-80155 and Japanese Utility Model Publication No. S53-20796, the length of an operation lever is also compelled to be shorten, and a larger force is therefore required for operating the operation lever, thus resulting in difficulty in operation of the operation lever.

In the clamping apparatus disclosed in Japanese Utility Model Publication No.

H4-13080, an operation lever is fixed to the forward end of a clamp member, thus causing a problem that the operation lever is obstructive to the clamping of the sanding sheet. When the clamp member is restored to the closing condition, the operation lever is returned suddenly by means of the spring associated with the clamp member, thus causing problems in safety.

0. It is an object of the present invention to overcome or ameliorate some of the o. disadvantages of the prior art, or at least to provide a useful alternative.

S00 :0 •SUMMARY OF THE INVENTION 15 Accordingly, the invention provides an apparatus for clamping a sanding sheet for a sander, which comprises: 00 0a clamp member for holding the sanding sheet on an oscillation plate of the sander in a closing condition and for releasing said sanding sheet from said oscillation plate in an opening condition; and an operation lever for causing said clamp member to be in any one of said closing condition and said opening condition; wherein: said clamp member is formed of a leaf spring so as to permit a resilient S"reversion of said clamp member from said closing condition to said opening condition, said clamp member having a bent portion, which is kept in an inclined state relative to said oscillation plate when said opening condition of said clamp member is maintained; and wherein said operation lever is pivoted on said oscillation plate so that one directional swing motion of said operation lever on a plane parallel with said oscillation plate causes said bent portion of said clamp member to be kept in the inclined state to maintain the opening condition thereof, and an opposite directional swing motion thereof causes said operation lever to be brought into contact with said bent portion of said clamp member to impart a larger force than a restoring force of said clamp member thereto so as to maintain the closing condition thereof, whereby said clamp member can be opened or closed in interlocking relation with the swing motion of said operation lever.

7 pparatus for clamping a sanding sheet for a sander, which prevents the operation lever [N:\LIBLLI02393:KEH from being obstructive to the working operation of the sander as well as the clamping of the sanding sheet, and permits easy and safe operation of the operation lever with a smaller force.

At least a portion of the above-mentioned operation lever, which is to be brought into contact with the clamp member may be formed of synthetic resin.

A click-stop mechanism may be provided between the operation lever and the clamp member.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings, wherein: FIG. 1 is a longitudinal cross-sectional view illustrating a sander provided with an apparatus of the present invention for clamping a sanding sheet; FIG. 2 is a transverse cross-sectional view of the sander, which illustrates the essence of the apparatus of the present invention; 15 FIG. 3 is a cross-sectional view cut along the line III-Ill in FIG. 2; FIG. 4 is a cross-sectional view cut along the line IV-IV in FIG. 2; So S o [N:\LIBLL]02393:KEH FIG. 5 is a plan view illustrating a clamp member of the apparatus of the present invention; FIG. 6 is a side view from the line VI-VI in FIG. 5, illustrating the clamp member of the apparatus of the present invention; FIG. 7 is a front view from the line VII-VII in FIG. 5, illustrating the clamp member of the apparatus of the present invention; FIG. 8 is a cross-sectional view cut along the line VIII-VIII in FIG. FIG. 9 is a plan view illustrating an operation lever of the apparatus lof the present invention; /o FIG. 10 is a rear view from the line X-X in FIG. 9, illustrating the operation lever of the apparatus of the present invention; 1 FIG. 11 is a front view from the line XI-XI in FIG. 9, illustrating the operation lever of the apparatus of the present invention; FIG. 12 is a left-hand side view from the line XII-XII in FIG. 9, 16 illustrating the operation lever of the apparatus of the present invention; FIG. 13 is a bottom view illustrating the operation lever of the apparatus of the present invention; and FIG. 14 is a cross-sectional view cut along the line XIV-XIV in FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Now, one of embodiments of an apparatus of the present invention for clamping a sanding sheet for a sander will be described in detail below with reference to the accompanying drawings.

6 The sander which is provided with the apparatus of the present invention for clamping the sanding sheet, has a housing in which an electric motor 2 is included, and there is provided an oscillation plate 3 below a skirt portion la of the housing 1, which is driven by the electric motor 2. The oscillation plate 3 has a base plate 3a connected to an output shaft 2a of the iC electric motor 2, and a pad plate 3b secured on the under surface of the base plate 3a by means of a securing means such as an adhesive agent, for supporting the sanding sheet 4 such as a sand paper on the under surface of the pad plate 3b. An eccentric shaft 2b is connected to the output shaft 2a of the electric motor 2, and the eccentric shaft 2b is fitted, through a bearing 6, .into a boss 5a formed on the base plate 3a. The oscillation plate 3 is supported on the skirt portion la of the housing 1 by means of elastic members 7 made of rubber or the like, which are arranged between the four corners of the oscillation plate 3 and the corresponding four portions of the skirt portion la, as shown in FIGS. 1 and 2. A plurality of elastic members 7 Sare provided for each of the four corners of the oscillation plate 3 as shown in FIG. 2, and a pair of opposite elastic members 7 of these members for each of the four corners of the oscillation plate 3 are connected at its upper ends to a connecting plate 8 as shown in FIG. 3. The elastic members 7 are connected to the housing 1 by inserting the connecting plate 3 into a groove 9 formed on the skirt portion la of the housing 1, and the elastic members 7 are connected, on the other hand, to the base plate 3a by securing the lower end portions of the elastic members 7 to the base plate 3a by means of a bolt 10 and a nut 11.

Such a supporting mechanism having the above-described elastic members 7 permits oscillating motion of the oscillation plate 3, the cyclically shaking motion of the oscillation plate 3 on a plane corresponding to the under surface 6 thereof, under the driving condition of the electric motor 2.

The housing 1 is composed of right and left-hand half portions as shown in FIGS. 1 and 4. After the electric motor 2 and the other parts are secured to one of these half portions, for example the right-hand half portion, the other of them, for example the left-hand half portion is put on the right- 0 lo hand half portion so that the respective peripheral edges of these half portions are brought into contact with each other, and then, these half portions are ofixed to each other by means of a fixing means such as screws. The operation Sof an on-off switch c provided on a grip portion lb of the housing 1 causes the electric motor 2 to be driven or stopped.

The clamping apparatus is designed so that the sanding sheet 4 such a sand paper can be held on the under surface of the oscillation plate 3.

The sanding sheet 4 is detachably held on the oscillation plate 3 by means of the clamping apparatus described below.

The clamping apparatus is provided with a clamp member 12 for 02 holding the sanding sheet 4 on the oscillation plate 3 in a closing condition and for releasing the sanding sheet 4 from the oscillation plate 3 in an opening condition; and with an operation lever 13 for causing the clamp member 12 to be in any one of the closing condition and the opening condition.

The clamp member 12 is provided for each of the right and left-hand sides of the oscillation plate 3 as shown in FIG. 3. The clamp member 12 is formed of a leaf spring so as to permit a resilient reversion thereof from the closing condition as shown in a solid line in FIG. 3 to the opening condition as shown in a two-dot chain line therein. Each clamp member 12 has an integral body as shown in FIGS. 5 to 8, which is composed of a jaw portion 12a to be brought into contact with the sanding sheet 4, leg portions 12b, 12c for supporting the clamp member 12 on the oscillation plate 3 and a resilient bent portion 12d for connecting the jaw portion 12a to the pair of leg portions 12b, 12c. The two leg portions 12b, 12c are provided for each clamp member 12.

/o One leg portion 12c has a hole into which a projection 14 formed on the base plate 3a is fitted as shown in FIG. 3, and is pressed against the base plate 3a by a boss 13a of the operation lever 13. The other leg portion 12b is put on the other projection 15 formed on the base plate 3a and is pressed against the projection 15 by the lower end of the above-described elastic member 7. Such "a construction causes the clamp members 12 to be fixed at the right and lefthand prescribed positions on the oscillation plate 3, respectively. The jaw portion 12a of the clamp member 12 located at the left-hand side in FIG. 3 projects in an obliquely left-hand upward direction to form a left-hand opening for inserting the left-hand end of the sanding sheet 4 between the jaw 2o portion 12a and the upper surface of the base plate 3a. The jaw portion 12a of the clamp member 12 located at the right-hand side in FIG. 3 projects in an obliquely right-hand upward direction to form a right-hand opening for inserting the right-hand end of the sanding sheet 4 between the jaw portion 12a and the upper surface of the base plate 3a. These clamp members 12 are kept in the opening condition to form the right and left-hand openings as described above. The operation levers 13 described below causes the jaw portions 12a of the clamp members 12 to be pressed down against the resiliency of the bent portion 12d onto the base plate 3a so as to kept in the closing condition in which the sanding sheet 4 is grasped between the jaw portions 12a and the base plate 3a, thus holding the sanding sheet 4 on the oscillation plate 3.

The single operation lever 13 is provided for each of the clamp members 12 as shown in FIG. 2. The operation lever 13 is pivoted as shown in FIGS. 2 and 3 on the oscillation plate 3 so that one directional swing motion of the operation lever 13 on a plane parallel with the oscillation plate 3 causes the clamp member 12 to be kept in the inclined state to maintain the opening condition thereof, and an opposite directional swing motion thereof causes the 10 operation lever 13 to be brought into contact with the inclined clamp member 12 to maintain the closing condition thereof.

S

Each operation lever 13 has a structure as shown in FIGS. 9 to 14, in which a handle portion 13b to be held by fingers of an operator and an o °operating portion 13c to be brought into contact with the clamp member 12 are S 15- arranged substantially at right angles with each other and connected to the circumferential surface of a boss portion 13a. The handle portion 13b and the operating portion 13c are formed into an arm-shape, respectively. With respect to each of the operation levers 13, a boss portion 13a has a hole into which the projection 14 formed on the base plate 3a so as to project vertically is swingably fitted so that, when the operation lever 13 is swung in one direction, the handle portion 13b is laid on the skirt la of the housing 1 and the operating portion 13c is moved along an arcuate locus as shown in a dashed line in FIG. 2 in the housing so as to be brought into contact with the bent portion 12d of the clamp member 12, and when the operation lever 13 is 2 swung in the opposite direction, on the other hand, the handle portion 13b is away from the skirt la of the housing 1 and the counter motion of the operating portion 13c is made along the arcuate locus mentioned above so as to release the contact of the operating portion 13c with the bent portion 12d of the clamp member 12. The above-mentioned arcuate locus for the end of the operating portion 13c extends substantially in a longitudinal direction of the bent portion 12d of the clamp member 12, and a plane including the arcuate locus intersects the clamp member 12 at a prescribed inclination angle so that a smaller force applied to the handle portion 13b permits the jaw portion 12a of the clamp member 12 to be pressed down against the resiliency of the bent portion 12d, thus maintaining the closing condition of the clamp l member 12.

e At least a portion of the operation lever 13, which is to be brought into contact with the clamp member 12, the operating portion 13c of the operation lever 13 is preferably formed of a relatively soft material such as ~synthetic resin in order to achieve the smooth bending motion of the clamp 0.00 6 member 12. The entire body of the operation lever 13 may be formed of synthetic resin or the like.

A click-stop mechanism is provided between the operation lever 13 and the clamp member 12 as shown in FIGS. 2 to 4. More specifically, the click-stop mechanism comprises a projecting portion 16 formed on the under surface of the forward end of the operating portion 13c and a recess portion 17 formed on the upper surface of the bent portion 12d of the clamp member 12, into which recess portion the above-mentioned projecting portion 16 may be fitted. When the operation lever 13 is swung to complete the closing motion of the clamp member 12, the projecting portion 16 of the operating portion 13c Q is fitted into the recess portion 17 of the bent portion 12d of the clamp member 12, with the result that an operator can perceive the completion of the holding of the sanding sheet by means of the clamp member 12. The projecting portion 16 may be formed on the upper surface of the bent portion 12d of the clamp member 12, and the recess portion 17 may be formed on the under surface of the forward end of the operating portion 13c of the operation lever 13. An additional recess portion 17 may be formed on the bent portion 12d of the clamp member 12 or the operating portion 13c of the operation lever 13 so that the operator can perceive the completion of the opening motion of the clamp member 12, and a further additional recess portion may be formed thereon so that the operator can perceive the clamp member 12 being kept in (0 the intermediate position between the closing condition and the opening condition.

A recess 18 is formed on the skirt la of the housing 1, which permits

S

the handle portion 13b to be received therein so as not to be obstructive to the working operation of the sander, when the operation lever 13 is swung to keep 16- the clamp member 12 in the closing condition, and also permits fingers of an •operator to be inserted therein, thus making it easy for the operator to hold the handle portion 13b of the operation lever 13.

Now, operation of the apparatus for clamping the sanding sheet for a sander of the embodiment of the present invention will be described below.

When the new sanding sheet 4 is held on the oscillation plate 3 of the sander prior to the sanding operation of the sander, the operation lever 13 is swung from the condition as shown in the left-hand and lower portion of FIG.

2 to the other condition as shown in the right-hand and upper portion of FIG.

2 by turning the operation lever 13 while grasping the handle portion 13b 9S thereof by fingers. The above-described operation is carried out for each of 0 the left and right-hand operation levers 13.

The above-described operation causes the handle portion 13b of the operation lever 13 to be swung on a plane parallel with the oscillation plate 3 so as to be pulled out from the recess 18 of the housing 1, with the result that 6- the operating portion 13c of the operation lever 13 is also swung in the housing 1, and the projecting portion 16 of the operating portion 13c is put out of the recess portion 17 of the bent portion 12d of the clamp member 12, thus being apart from the bent portion 12d. The release of the clamp member 12 from the contact with the operating portion 13c of the operation lever 13 IU0 causes the opening motion of the clamp member 12 under the function of resiliency of the bent portion 12d thereof, with the result that the clamp member 12 as arranged at the left-hand portion of FIG. 3 resiliently reverts from the closing condition as shown in a solid line to the opening condition as shown in a two-dot chain line, and the clamp member 12 as arranged at the right-hand portion of FIG. 3 resiliently reverts from the closing condition as shown in a two-dot chain line to the opening condition as shown in a solid line.

o•Each of the clamp members 12 kept in the upwardly inclined state to maintain the opening condition thereof permits the release of the worn-out sanding sheet 4, thus making it possible to remove the worn-out sanding sheet 4 from 0L the oscillation plate 3.

The holding of the new sanding sheet 4 on the oscillation plate 3 is completed by putting the new sanding sheet 4 on the under surface of the pad plate 3b of the oscillation plate 3, turning up the both end portions of the sanding sheet 4 to put them on the upper surface of the base plate 3a of the -2S oscillation plate 3, and turning the operation lever 13, while grasping the handle portion 13b thereof by fingers, into a condition as shown in the lefthand and lower portion of FIG. 2 from a condition as shown in the right-hand and upper portion thereof. The above-described operation is also carried out for each of the left and right-hand operation levers 13.

The above-described operation causes the handle portion 13b of the Soperation lever 13 to be swung on the plane parallel with the oscillation plate 3 so as to be received in the recess 18 of the housing 1, with the result that the operating portion 13c of the operation lever 13 is also swung in the housing 1, and the projecting portion 16 of the operating portion 13c is moved along the arcuate locus as shown in the dashed line in FIG. 2, thus causing the bent 0/ portion 12d of the clamp member 12 to be gradually pressed down.

The arcuate locus for the end of the operating portion 13c extends substantially in a longitudinal direction of the bent portion 12d of the clamp member 12, and a plane including the arcuate locus intersects the clamp 0 amember 12 at an acute angle, with the result that a smaller force applied to I" the handle portion 13b permits the jaw portion 12a of the clamp member 12 to be pressed down to the base plate 3a against the resiliency of the bent portion 12d, thus maintaining the closing condition of the clamp member 12, and a large holding force for the sanding sheet 4 by means of the clamp member 12 can be ensured. When the operation lever 13 is swung to complete the closing motion of the clamp member 12, the projecting portion 16 of the operating portion 13c is fitted into the recess portion 17 of the bent portion 12d of the clamp member 12, with the result that an operator can perceive the completion of the holding of the sanding sheet by means of the clamp member 12.

When the above-mentioned operation is completed, the clamp member 12 as arranged at the left-hand portion of FIG. 3 is deformed from the opening condition as shown in the two-dot chain line to the closing condition as shown in the solid line, and the clamp member 12 as arranged at the right-hand portion of FIG. 3 is deformed from the opening condition as shown in the solid line to the closing condition as shown in the two-dot chain line.

Such a closing condition in which the jaw portion 12a of each of the clamp members 12 is pressed down to the base plate 3a permits the holding of the both ends of the sanding sheet 4 between the jaw portion 12a and the upper surface of the base plate 3a, thus making it possible to hold firmly the sanding lo sheet 4 on the oscillation plate 3.

to to 66 After the completion of the above-described operation, the start of the electric motor 2 causes the oscillation motion of the oscillation plate 3 along the circular locus on the plane of the oscillation plate 3, thus making it possible to apply the sanding treatment to an object to be sanded by means of 15 the sanding sheet 4 held on the oscillation plate 3.

According to the present invention as described in detail, the operation lever which is pivoted on the oscillation plate so as to be swung on a plane parallel with the oscillation plate does not project upward from the housing of the sander, thus making it possible to solve the obstructive problem to the working operation of the sander. The construction in which the operation lever does not project upward from the housing of the sander also causes the length of the operation lever to be increased as long as possible, thus making it possible to carry out the opening and closing operation of the clamp member by a smaller force, and to increase the holding force of the 2 sanding sheet so as to secure firmly the sanding sheet on the oscillation plate.

Since the apparatus of the present invention has a construction in which the clamp member is formed of the leaf spring so as to permit the resilient reversion of the clamp member from the closing condition to the opening condition in an inclined state, and the operation lever is pivoted on the oscillation plate so that one directional swing motion of the operation lever on Sa plane parallel with the oscillation plate causes the clamp member to be kept in the inclined state to maintain the opening condition thereof, and an opposite directional swing motion thereof causes the operation lever to be brought into contact with the inclined clamp member to maintain the closing condition thereof, the sudden movement of the operation lever does not occur /O even when the resilient force by the clamp member is applied to the operation 9.

lever, thus permitting the improvement in safety.

SO

.9 9 When at least a portion of the operation lever, which is to be brought into contact with the clamp member is formed of synthetic resin, there can be 9* achieved the smooth movement of the operation lever on the clamp member which is formed for example of metal. It is therefore possible to make the opening and closing operation of the clamp member smooth when the sanding sheet is replaced.

When a click-stop mechanism is provided between the operation lever and the clamp member, an operator can perceive the completion of the holding 2L of the sanding sheet by means of the clamp member 12, thus making it easy to carry out the replacement operation of the sanding sheet.

16 The claims defining the invention are as follows:- 1. An apparatus for clamping a sanding sheet for a sander, which comprises: a clamp member for holding the sanding sheet on an oscillation plate of the sander in a closing condition and for releasing said sanding sheet from said oscillation plate in an opening condition; and an operation lever for causing said clamp member to be in any one of said closing condition and said opening condition; wherein: said clamp member is formed of a leaf spring so as to permit a resilient reversion of said clamp member from said closing condition to said opening condition, said clamp member having a bent portion, which is kept in an inclined state relative to said oscillation plate when said opening condition of said clamp member is maintained; and wherein •15 said operation lever is pivoted on said oscillation plate so that one directional swing motion of said operation lever on a plane parallel with said oscillation plate causes said bent portion of said clamp member to be kept in the inclined state to maintain the opening condition thereof, and an opposite directional swing motion thereof causes said operation lever to be brought into contact with said bent portion of said clamp member to impart a larger force than a restoring force of said clamp member thereto so as to maintain the closing condition thereof, whereby said clamp member can be opened or closed in interlocking relation with the swing motion of said So operation lever.

2. An apparatus as claimed in claim 1, wherein: at least a portion of said operation lever, which is to be brought into contact with said clamp member is formed of synthetic resin.

3. An apparatus as claimed in claim 1 or 2, wherein: a click-stop mechanism is provided between said operation lever and said clamp member.

[N:\LIBLL]02393:KEH

Claims

4. An apparatus for clamping a sanding sheet, the apparatus being substantially as hereinbefore described with reference to the accompanying drawings. Dated 27 January, 1998 Ryobi Ltd. Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON 6 0 0 [N:\LIBLL]01303:vsg APPARATUS FOR CLAMPING SANDING SHEET FOR SANDER Abstract of the Disclosure An apparatus for clamping a sanding sheet for a sander comprising a clamp member (12) for holding the sanding sheet on an oscillation plate of the sander in closing condition and for releasing the sanding sheet from oscillation plate in an opening condition; and an operation lever (13) for causing the clamp member to be in any one of the closing condition and the opening condition. The clamp member (12) is formed of a leaf spring so as to permit a resilient reversion of the clamp member from the closing condition to the opening condition in an inclined state. The operation lever (13) is pivoted on the oscillation plate so that one directional swing motion of the operative lever on a plane parallel with the oscillation plate causes the clamp member to be kept in o*.00@ *the inclined state to maintain the operating condition thereof, and an opposite directional swing motion thereof causes the operation lever to be brought into contact with the inclined clamp member to maintain the closing condition thereof. *0 0 0 0o oo0 [N:\LIBLL]01303:vsg