Abstract:
A sander has two abrasive-supporting base parts mounted to an oscillating drive mechanism. The base parts may support a sandpaper sheet, or the like, and are connected to one another in a manner allowing ready reconfiguration for different applications. One of the base parts is connected by a pivoting coupling to the other for movement between extended and retracted positions. Latching means releasably lock the coupling so as to hold the parts in the extended position.

Description:
TECHNICAL FIELD 
     The present invention relates to sanders, particularly sanders with an abrasive-supporting base comprising at least two parts. 
     BACKGROUND OF THE INVENTION 
     Orbital or in-line sanders have a base for supporting an abrasive sheet, or consisting of an abrasive block or pad. This abrasive-supporting base is mounted to a motor-driven oscillating mechanism. The sander may be configured to accept bases of different shapes (e.g. rectangular, triangular or elongate fingers) for differing applications, and typically these bases are mounted by screw fasteners. Providing detachable bases of this kind makes the sander more versatile, however this arrangement is not without some drawbacks. For instance, the replacement operation can be time-consuming and there is a need to carry or store replacement bases, some of which may be small parts that are readily misplaced. 
     In addition to the entire base being detachable, it is known to provide abrasive-supporting bases made in one or more detachable parts. EP 1 166 963 describes a sander in which different shaped tips may be connected to provide different shaped base assemblies. The detachable tips are releasably connected by hooks that cooperate with a spring-loaded latch, thereby avoiding the need for tools to re-configure the base. However, this design does not otherwise address the drawbacks of this arrangement, such as those mentioned above. It is an object of the present invention to overcome or substantially ameliorate the above disadvantages or more generally to provide an improved sander. 
     DISCLOSURE OF THE INVENTION 
     According to one aspect of the present invention there is provided a sander comprising: 
     an abrasive-supporting base having first and second parts, the first part being mounted to an oscillating drive mechanism, 
     a coupling, and wherein 
     the second part is pivotally connected to the first part by the coupling for movement between an extended position in which the second part is substantially aligned with the first part and at least one retracted position, and wherein 
     latching means releasably lock the coupling so as to hold the second part in the extended position. 
     With the second part in its retracted position either the first part or the second part may be used, while in the extended position both the first and second parts are used together. The invention thus provides a sander that is readily reconfigurable for different applications, without the need to attach and detach base parts. Preferably the first and second parts have respective planar surfaces which are aligned in a substantially coplanar manner in the extended position. 
     Preferably in the extended position in which the second part is substantially aligned with the first part, respective planar faces on the first and second parts are aligned parallel with one another. The retracted position may comprise one or more retracted positions angularly spaced from the extended position. 
     Preferably the second part has a planar surface generally symmetrical about a longitudinal centre line and having an outer peripheral edge forming a forward most tip region having two edges joined at an acute angle and a pair of straight lateral edges extending rearwardly from the tip region, the straight lateral edges being substantially parallel. 
     Preferably the second part has a rearward edge complementary to a forward edge of the first part. Preferably the forward edge of the first part is a pointed tip and the second part has a concave rearward edge in which the pointed tip may be received. Advantageously this arrangement makes it possible to have a point with an acute internal angle on both of the base parts, making both base parts suitable for sanding internal corners. 
     Preferably the forward most tip region has a thickness conspicuously smaller than the spacing between the two lateral edges. Being relatively thin, the second part may be used to access narrow spaces, as between louvres. 
     Preferably the first part has a planar surface generally symmetrical about the longitudinal centre line and a forward most tip section having two edges joined at an acute angle. 
     Preferably the coupling comprises an elongate coupling member defining a pivot axis, the coupling member being received in an aperture in the first part and second part. Preferably the pivot axis is transverse to the longitudinal centre line. 
     Optionally the latching means may releasably lock the second part in the/each retracted position. 
     The latching means may comprise a locking member slidably received in the second part, the locking member including two fingers, each finger being received in a respective recess in the first part to lock the coupling against rotation. Preferably the locking member is elongate and received to slide in an aperture in the first part, which aperture extends parallel to the longitudinal centre line, and wherein the fingers are formed on one end of the locking member. 
     The sander may further comprise a detent to hold the second part in the retracted position. Preferably the detent comprises an interference lobe on the second part, which interference lobe cooperates with a surface on the first part. 
     In one embodiment the latching means comprises a finger rigidly fixed to the second part, the finger has an longitudinal axis, the coupling member is received in an opening elongated in the longitudinal direction, a resiliently-biased detent member cooperates with a concavity to prevent relative movement of the first and second parts parallel to the axis, and wherein the opening elongated in the longitudinal direction cooperates with the coupling member to allow both rotation about an axis of the coupling member and longitudinal sliding of the second part relative to the first part. 
     Preferably the coupling member includes an elongate cylindrical face and a flat face, the elongated opening includes a cylindrical portion corresponding to the diameter of the elongate cylindrical face and a relatively narrower mouth portion. 
     In another embodiment the first and second parts have respective apertures, each aperture having a respective keyway portion therein; the coupling member is received in the apertures for pivotally connecting the first and second parts, the coupling member having axially spaced key portions of complementary shape to the keyway portions, the coupling member being moveable substantially parallel to a pivot axis of the coupling member between a first position and a second position, wherein in the first position the key portions engage the keyway portions to prevent rotation of the coupling and in the second position the key portions are released from one of the keyway portions to allow rotation of the coupling. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred forms of the present invention will now be described by way of example with reference to the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of a sander according to a first embodiment of the invention; 
         FIGS. 2 and 3  are perspective views of the base member of the sander of  FIG. 1  in first and second configurations respectively; 
         FIG. 4  is an exploded view of the base member of  FIGS. 2 and 3 ; 
         FIG. 5  is a fragmentary section in a longitudinal upright plane through the base member of  FIGS. 2 and 3 ; 
         FIG. 6  is an exploded perspective view from above of a base member of a sander according to a second embodiment of the invention; 
         FIG. 7  is a perspective view from below of the second part of the base member of  FIG. 6 ; 
         FIGS. 8   a ,  8   b  and  8   c  are fragmentary side views showing the second part of the base member of  FIG. 6  in retracted, intermediate and extended positions respectively; 
         FIG. 9  is a fragmentary sectional view in an upright longitudinal plane of the second part of the base member of  FIG. 6 ; 
         FIG. 10  is an exploded perspective view from above of a base member of a sander according to a third embodiment of the invention; 
         FIGS. 11 and 12  are transverse sectional views in an upright plane showing the coupling between the parts comprising the base member of  FIG. 10  in locked and released positions respectively, and 
         FIG. 13  is a perspective view of a shaft connecting the parts of the base member of  FIG. 10 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The first embodiment of the detail sander  10  of the invention shown in  FIGS. 1-5  is utilized for sanding inside corners and other difficult to reach locations. The sander  10  has a body  12 , including a grip portion  13  by which it may be held by a user. A recess  14  in is provided in the front of the body  12 . The body  12  encloses a motor (not shown) and an oscillatory drive mechanism (not shown). A base member  15  disposed below the body  12  is mounted to the oscillatory drive mechanism for supporting a work member (not shown). The work member may be sandpaper sheet (not shown) or similar abrasive material removably attached to a planar lower face of the first base member  15 , as by hook and loop fasteners, or adhesive. 
     The base member  15  comprises a first part  15   a  directly connected to the oscillatory drive mechanism, and a second part  15   b  connected to the part  15   a  by a coupling  16 , such that the first base member  15   a  may pivot relative to the second base member  15   b  about the transverse axis  17 . The second part  15   b  pivots between an extended position (shown in  FIGS. 1 and 3 ) and at least one retracted position (shown in  FIG. 2 ). In the extended position a planar lower face  18  of the part  15   b  may be aligned generally coplanar with a planar lower face  19  of the first part  15   a , to effectively extend the working area of the of the first part  15   a . In the retracted position, the second part  15   b  is rotated (approximately 110 degrees) and, in plan view lies generally within the periphery  20  of the first part  15   a . With the second part  15   b  in its retracted position, at least part of the second part  15   b  may be received in the recess  14 . By providing first and second parts in this manner, a versatile tool is obtained that is readily re-configurable. 
     The second part  15   b  is generally symmetrical about a longitudinal centre line  21 , with an outer peripheral edge  26  forming a forward most tip region  31  having two straight edges  27 ,  28  joined at an acute angle. A pair of lateral edges  29 ,  30  extend rearwardly from the tip region  31  substantially parallel to one another. The second part  15   b  has a concave rearward edge  48  complementary to a pointed forward edge  22  of the first part  15   a , received their in the extended position. The forward most tip region  31  has a thickness conspicuously smaller than the spacing S between the two lateral edges  29 ,  30  making it sufficiently thin to access narrow spaces, as between louvres. 
     The periphery  20  of the first part  15   a  is also generally symmetrical about longitudinal centre line  21 . Arcuate lateral edges  23 ,  24  of the first part  15   a  intersect at an acute angle to form the pointed tip or forward edge  22 . 
     The coupling  16  comprises a pivot  32  having a cylindrical outer surface defining the pivot axis  17 . The first part  15   a  includes a centrally positioned projection  33  with a transverse opening  34  therein. The second part  15   b  has a pair of projections  35 , each with an opening  36 . The pivot  32  extends through the openings  34 ,  36  and is thus connected in double shear. 
     Latching means for releasably locking the coupling  16  to hold the second part  15   b  in the extended position, includes a locking member  37  slidably received in an aperture  41  in the second part  15   b . In the preferred embodiment, the first part  15   a  and second part  15   b  may be moulded polymeric components and the locking member  37  may be made from metal. The locking member  37  is elongate having a bar portion  40  at an outer end which bifurcates to form two fingers  38  at the opposing inner end. The bar portion  40  is received in the opening  41 , such that the fit prevents rotation of the locking member  37  but permits sliding. A spring  42  engages the locking member  37  urging the fingers  38  rearwardly. A button  46  is received in an aperture  47  in the second part  15   b  to slide longitudinal. The button  46  is fixed to the outer end of the locking member  37 . Parallel apertures  39  are disposed in the first part  15   a  in registration with the fingers  38 , and with the fingers  38  received in the apertures  39  the second part  15   b  is latched against rotation. To release the second part  15   b  the button is slid forward, withdrawing the fingers from the apertures  39 . 
     The sander may further comprise a detent to hold the second part  15   b  in the retracted position. The detent may comprise an interference lobe  50  formed on each of the projections  35 . The projections  35  further include flats  52  which abut the faces  51  of the first part  15   a  preventing rearward rotation of the second part  15   b . The interference lobes  50  also abut the face  51  but prevent forward rotation of the second part  15   b , and thus serve to hold the second part  15   b  in the retracted position. To move the second part  15   b  to the extended position the interference lobes  50  must both go over-centre, and this is permitted by virtue of the inherent resilience of the materials from which the parts are made and of the construction, allowing the requisite elastic deformation each time this occurs. 
       FIGS. 6-9  illustrate a second embodiment of the invention, and like numbers are used to refer to like components. The first part  215   a  and the second part  215   b  of the base member  215  are mutually connected for rotation by a coupling  216  including a bar  232  of an elongate cylindrical form, with coaxial semi-cylindrical faces  55  separated by opposing, flat faces  56 . The bar  232  defines the transverse pivot axis  17  and its opposing ends are received in complementary holes  57  in the projections  35 , thereby preventing rotation of the bar relative to the second part  215   b . In the extended position a planar lower face  18  of the part  215   b  may be aligned generally parallel with a planar lower face  19  of the first part  215   a . The coupling  216  includes a transverse opening  234  in the projection  33 . The opening  234  is elongated in the longitudinal direction, having at its outer end a cylindrical portion  59  corresponding to the diameter of the cylindrical faces  55 , and at its inner end a narrow mouth  60  of dimension corresponding to the spacing between the flat faces  56 . The fingers  238  are elongated in the direction of the longitudinal axis  21  and are integral with the second part  215   b . A spring  62  and ball  63  are disposed in a recess  64  in the first part  215   a , such that the spring urges the ball  63  outwardly. 
       FIGS. 8   a - 8   c  illustrate the turn-and-push operation of the coupling  216 . With the second part  215   b  in its retracted position ( FIG. 8   a ) the bar  232  is received in the cylindrical portion  59  and is thus able to turn forward in direction  65  until the second part  215   b  abuts the first part  215   a  ( FIG. 8   b ). Next, the second part  215   b  may be pushed rearwardly in direction  66 , this rearward movement enters the bar  232  into the narrow mouth  60 , while the fingers  238  are simultaneously entered in the recesses  39  ( FIG. 8   c ). The coupling  216  and the fingers  238 /recesses  39  thereby cooperate to prevent rotation of the second part  215   b  in the extended position. 
     As shown in  FIG. 9 , the second part  215   b  includes a first recess  67  and a second recess  68 . The ball  67  is partially received in the first recess  67  to hold the second part  215   b  in the extended position, and is likewise partially received in the first recess  68  to hold the second part  215   b  in the retracted position. 
     A third embodiment of the invention is shown in  FIGS. 10-14 . The first part  315   a  and the second part  315   b  are mutually connected for rotation by a coupling  316  including a coupling member in the form of a shaft  332 . The shaft  332  has an elongate, cylindrical section  70  from which three equally circumferentially spaced key portions  71  project. The key portions  71  are integral with the shaft  332  and extend axially from a head  73  formed on one end of the shaft  332  to finish at a first intermediate position between the head  73  and opposing end  72 . Each key portion  71  has a partially cylindrical face  76  coaxial with the surface  70 . A discontinuity  74  positioned at a second intermediate position between the head  73  and opposing end  72  divides the key portions  71  into inner portions  71   a  and outer portions  71   b.    
     The coupling  316  includes a transverse opening  334  in the projection  33  which includes three equally circumferentially spaced keyway portions  75 , for receiving the portions  71 , thereby preventing rotation of the shaft  332  relative to the first part  315   a.    
     The head  73  of the shaft  332  is disposed on the left side of the sander. Opposing ends of the spring  84  bear against the button  83  and the second part  315   b  thereby urging the shaft  332  toward the right. The apertures  336  in the projections  35  are of like form, comprising axially spaced portions  80   a ,  80   b  and  81   a ,  81   b  on their left and right sides respectively. The portions  80   a ,  80   b  have like form to the opening  334  with keyway portions  75  for receiving the key portions  71 . The portions  81   a ,  81   b  comprise cylindrical recesses. A button  83  is fixed to the end  72  of the shaft, and disposed on the right side of the sander at least partially within the cylindrical portion  81   b  of the opening  336 . 
     With the second part  315   b  in its extended position and the shaft  332  in its locked position ( FIG. 11 ), the inner key portions  71   a  are received in the portion  81   b , and the outer key portions  71   b  are received in the portion  80   a , the key portions and keyway portions thereby cooperating to lock the second part  315   b  against rotation about the shaft  332 . 
     The shaft  332  defines the transverse pivot axis  17  and is moved to its unlocked position ( FIG. 12 ) by pressing the button  83 . In this unlocked position the inner key portions  71   a  are withdrawn from the portion  81   b , and the outer key portions  71   b  are withdrawn from the portion  80   a . At the same time the inner key portions  71   a  are entered into the cylindrical portion  81   a . With the key portions and keyway portions connecting the shaft  332  and second part  315   b  thereby released, and the outer faces  76  and the button  83  engaged in the cylindrical faces  81   a ,  81   b  the second part  315   b  is then free to rotate to its retracted position. 
     Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof.