Abstract:
An apparatus for resurfacing a pair of guide plugs includes a turntable rotatably mounted on a frame having cutting tools interacting with resurfaceable guide plugs mounted on a reciprocating slide assembly which includes a guide support block adapted for reciprocating motion with respect to the cutting tools. The block has a pair of saw guides selectively attached thereto so as to be parallel to each other so that parallelism is maintained during the resurfacing process.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
         [0001]    Not applicable.  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not applicable.  
         REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX  
         [0003]    Not applicable.  
         BACKGROUND OF THE INVENTION  
         [0004]    Conventional resurfacing machines of the type that resurfaces guide plugs used in the sawmill industry have a pair of opposed upper and lower turntables. The turntables each have a replaceable cutting tool which includes a diamond stylus or the like. A workpiece is fed into the space between the rotary turntables and is resurfaced by the scraping action of the cutting tools. An example of this type of machine is shown in the Emter U.S. Pat. No. 4,685,845 entitled GUIDE PAD RESURFACING APPARATUS. In this patent, each turntable includes a slot which receives a rectangular cutting tool containing a diamond stylus. The tool is held in the slot by a screw, and cutting depth is regulated by an adjustment screw bearing against the tool from the other side of each turntable. The adjustment screw torsions the tool slightly causing it to bend to achieve proper depth. A tool of this type can be found in U.S. Pat. No. 6,319,104.  
           [0005]    Resurfacing machines of this type use a pair of turntables to resurface the pads on opposite sides of a single saw guide. In conventional sawmill operations however, there are guide pads on either side of a saw blade. This calls for two saw guides. The guide pads must be milled to strict tolerances and it is important that the guide pad surfaces on either side of the saw blade be parallel to one another. It is very difficult, however, in a resurfacing operation in which guide pads are resurfaced one at a time to insure that any two guide pads on different saw guides will have perfectly parallel surfaces. Small differences in set-up and alignment of individual guide pads can change the angle at which the resurfacing operation takes place. While the intent is that the guide pads be perfectly horizontal relative to the turntables and cutting apparatus, in practice this is not always the case, because there are several sources of error that can affect alignment, and hence parallelism, of the guide pads.  
           [0006]    One major source of inaccuracy is the sliding support block to which the guide pads are affixed. This block is attached to a motor that causes it to slide reciprocally along a frame so that it moves the guide pad into and out of engagement with the cutting tools located on the spinning turntables. The guide pad is usually connected to a holder by a bolt or the like, which holds it in the horizontal plane. Small differences in the attachment of individual saw guides can mean that one saw guide may be resurfaced at an angle that is slightly different from the next or previous one.  
           [0007]    The resurfacing process is accomplished by tools having diamond-tipped heads which are affixed to the upper and lower turntables. The turntables rotate causing a series of arcs to be cut into the surfaces of the pads. A conventional support block slides on runners which are long rails arranged on the frame. The block includes cutout portions on its underside which are slots milled to fits the rails. Thus, the weight of the support block bears directly against the two raised rails bolted to the frame.  
           [0008]    Both the rails and the slots must be machined to very close tolerances. The rails have to be precisely aligned and must undergo a regrinding operation after manufacture. Further, they have to be heat-treated for hardening to keep wear to a minimum and to reduce “galling.” Galling is the tendency of metal filings to smear into the surface over time and create small ridges or bumps. Further, when the machines are shipped, any shock or jarring can cause the rails to become misaligned. Any misalignment can cause the guide pads to be resurfaced unevenly.  
         BRIEF SUMMARY OF THE INVENTION  
         [0009]    An apparatus for resurfacing a pair of guide plugs on different saw guides includes a turntable rotatably mounted on a frame having cutting tools interacting with resurfaceable guide plugs mounted on a reciprocating slide assembly which includes a guide support block adapted for reciprocating motion with respect to the cutting tools. The block has a pair of oppositely disposed saw guides selectively attached thereto so as to be parallel to each other so that parallelism is maintained during the resurfacing process. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL DRAWINGS  
       [0010]    [0010]FIG. 1 is a top view of a preferred embodiment of a resurfacing machine for milling two guide pads simultaneously.  
         [0011]    [0011]FIG. 2 is a partial side view of the machine of FIG. 1 taken along line  2 - 2 .  
         [0012]    [0012]FIG. 3 is a rear view taken along line  3 - 3  of FIG. 1.  
         [0013]    [0013]FIG. 4 is an exploded perspective view of a sliding support block and attachable guide pads. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]    Referring to FIG. 1, a resurfacing apparatus  10  includes a frame  12  supporting a turntable  14 . The turntable  14  has top and bottom surfaces  16  and  18 , respectively (refer to FIG. 2). The turntable  14  is mounted on a rotary spindle  20  which is driven by a motorized belt or the like  22 . A pair of resurfacing tools  24   a  and  24   b  are attached to the top and bottom surfaces  16  and  18 , respectively, of the turntable  14 . Each of the tools  24   a ,  24   b  has an abrading tip  26   a ,  26   b.    
         [0015]    A sliding support block  30  carries a pair of saw guides  28   a  and  28   b  into sliding engagement with the turntable  14  and cutting tools  24   a ,  24   b . A top plate  31  is connected to the support block  30  by way of spacers  33   a  and  33   b  which are dimensioned to match the thickness of the saw guides, such as saw guide pad  28   b , so that they are secured firmly to the sliding support block  30 .  
         [0016]    The pair of saw guides  28   a  and  28   b  are attached to the sliding support block  30  by a bolt  32  and a washer  34 . The saw guides  28   a  and  28   b  have pads or plugs  36   a  and  36   b , respectively, which are the wear parts that are resurfaced by the action of the spinning turntable  14  and the tools  24   a  and  24   b . The sliding support block  30  rests on the frame  12  and is moved back and forth in the reciprocal motion indicated by the arrow in FIG. 2. The frame  12  has an elongate slot  38  which accommodates a pin  40  which extends downwardly from the sliding support block  30 . A link or tie-rod  42  is coupled to the pin  40  and the other end of the tie-rod  41  is coupled to a reciprocating motor (not shown). The reciprocating motor moves the sliding support block and the attached guide pads  36   a  and  36   b  back and forth while the turntable  14  is spinning. This enables the abrading process to take place which is a resurfacing of the pads by the tools  24   a  and  24   b  cutting a series of fine circular arcs across the pads.  
         [0017]    The sliding support block  30  and the top plate  31  are machined so that their upper and lower surfaces are exactly parallel. Thus, when the saw guides  28   a  and  28   b  are fastened between the support block  30  and top plate  31 , the pads  36   a  and  36   b  will be aligned perfectly parallel to each other. Since the top and bottom surfaces of the turntable  14  are also parallel, and both the turntable and support block are supported on a common frame  12 , the resurfacing operation will be conducted so that the resurfaced guide pad plugs  36   a  and  36   b  will be parallel to each other within extremely close tolerances.  
         [0018]    In order to insure the parallelism of the support block  30  and thus the guide pads  36   a  and  36   b , the support block is constructed so that it includes three bearing surfaces  40 ,  42 , and  44  on the bottom of the support block  30  which bear directly against the top surface  46  of the frame  12 . A three-point bearing uniquely defines the plane of the support block and is inherently stable.  
         [0019]    In order to preserve the longitudinal alignment of the support block  30 , a pair of guides  50 ,  51  are connected to the bottom edges of the support block  30 . It will be appreciated that, in order to create the three-point contact surface for the support block  30 , it is necessary to make the block  30  wider than the bearing surface portion of the frame  12 . The guides  50  and  51  are coupled by pins or the like (not shown) to the support block  30  and are dimensioned so that they clamp the block  30  squarely to the sides of the frame  12 . The guides may be made of a heavy plastic or composite material that has a low coefficient of friction on steel.  
         [0020]    The use of the sliding support block  30  and its three bearing surfaces bearing directly on the top surface  46  of the frame  12  provides for manufacturing techniques that are simpler than have heretofore been necessary. The top piece  46  of the frame  12  may be cast, heat-treated and ground without milling. The support block  30  is cast and ground on the top and bottom and thus is able to provide the three-point contact surface without milling. Elimination of the milling step for these surfaces makes fabrication much less expensive.  
         [0021]    While the invention has been shown as being particularly useful in the type of guide pad apparatus shown in U.S. Pat. No. 4,685,845, it could be equally useful in other types of resurfacing apparatus as well. In fact, any application in which a pair of wear parts must be resurfaced simultaneously so as to provide parallelism between them may utilize the features of the invention. Furthermore, although the abrading tool shown in the preferred embodiment has been the tool of the type shown in U.S. Pat. No. 6,319,104, any other type of conventional abrading or resurfacing tool could be used, either in a spinning turntable configuration or with a different type of machine.