Patent Publication Number: US-6655427-B1

Title: Wood planing machine with an error reducing unit for a workpiece thickness to be removed

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority of Taiwanese Application No. 091211330, filed on Jul. 24, 2002. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a wood planing machine, more particularly to a wood planing machine with an error reducing unit for a workpiece thickness to be removed. 
     2. Description of the Related Art 
     Referring to FIGS. 1 to  3 , a conventional wood planing machine  10  is shown to include a base  11  having left and right sides, left and right pairs of posts  12  extending uprightly from the left and right sides of the base  11 , a cutter carriage  13  having left and right carriage ends  131  mounted slidably and respectively on the left and right pairs of posts  12 , and left and right screw rods  16  mounted rotatably on the left and right sides of the base  11 . Tubular left and right threaded members  15  extend through two through holes in the left and right carriage ends  131 . The left and right screw rods  16  extend through and threadedly engage the threaded members  15 , respectively. Left and right fastening nuts  19  threadedly and respectively engage the threaded members  15  so as to secure the threaded members  15  on the cutter carriage  13 . A transmission unit  18  includes two sprockets  181  fixed to lower ends of the left and right screw rods  16 , and a transmission chain  182  trained on the sprockets  181  so as to permit synchronous rotation of the left and right screw rods  16 , which, in turn, results in vertical movement of the cutter carriage  13  relative to the base  11 . A handle  17  is mounted on a top end of the right screw rod  16  to facilitate turning of the left and right screw rods  16 . 
     Referring to FIG. 4, the cutter carriage  13  is parallel to the base  20 , and the threads  150  of the threaded members  15  rest on the threads  160  of the screw rods  16  due to the weight of the cutter carriage  13 . Thus, clearances  161  are formed between the threads  150  of the threaded member  15  and the threads  160  of the screw rods  16 . As such, the threaded members  15  and the carriage  13  can move relative to the screw rods  16 , thereby resulting in an increase in error for workpiece thickness that is to be removed. 
     SUMMARY OF THE INVENTION 
     Therefore, the object of this invention is to provide a wood planing machine with an error reducing unit that can prevent movement of a cutter carriage relative to a set of upright screw rods. 
     Accordingly, a wood planing machine of the present invention includes: a base having four corners; four hollow posts extending uprightly from the corners of the base, respectively, each of the posts being formed with an axial slot for access to an interior thereof; four screw rods extending rotatably and uprightly from the corners of the base through the posts, respectively, each of the screw rods having an externally threaded portion that is formed with an external thread; a cutter carriage having four corners mounted respectively, vertically and slidably on the posts, and a horizontal bottom surface; a transmission unit connected to the screw rods to permit synchronous rotation of the screw rods; and an error reducing unit including four tubular threaded members that are secured respectively to the four corners of the carriage, that are disposed respectively within the posts in such a manner that the threaded members are exposed from the axial slots in the posts, and that define axially extending threaded bores respectively engaging the screw rods such that rotation of the screw rods results in movement of the carriage along the posts. Each of the threaded members has an internally threaded portion defining a respective one of the axially extending threaded bores and engaging the externally threaded portion of the respective one of the screw rods  50 , and a circumferential slot formed through a wall of the internally threaded portion so as to divide the internally threaded portion into an upper part and a lower part. The upper part is disposed above the circumferential slot, and has a bottom surface that defines a top end of the circumferential slot. The lower part is disposed below the circumferential slot, and is formed with a vertically extending threaded bore therethrough. Each of the upper and lower parts is formed with an internal thread that engages the external thread of the respective one of the screw rods. The error reducing unit further includes four locking bolts that engage respectively the vertically extending threaded bores in the threaded members and that press against the bottom surfaces of the upper parts of the internally threaded portions of the threaded members such that the internal threads of the upper parts of the threaded members press upwardly against the external threads of the screw rods and such that the internal threads of the lower parts of the threaded members press downwardly against the external threads of the screw rods so as to lock the internally threaded portions of the threaded members on the externally threaded portions of the screw rods. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and advantages of this invention will become more apparent in the following detailed description of the preferred embodiment of this invention, with reference to the accompanying drawings, in which: 
     FIG. 1 is a perspective view of a conventional wood planing machine; 
     FIG. 2 is a fragmentary exploded perspective view of the conventional wood planing machine; 
     FIG. 3 is a partly sectional fragmentary schematic view of the conventional wood planing machine, in which a cutter carriage and a base are shown in phantom lines; 
     FIG. 4 illustrates how a thread of a threaded member rests on a thread of a screw rod in the conventional wood planing machine; 
     FIG. 5 is a perspective view of a preferred embodiment of a wood planing machine according to the present invention; 
     FIG. 6 is a fragmentary exploded view of the preferred embodiment, illustrating how a threaded member is mounted on a screw rod; 
     FIG. 7 is an enlarged, fragmentary, partly sectional perspective view of the threaded member shown in FIG. 6; 
     FIGS. 8 and 9 are fragmentary sectional views of the preferred embodiment prior to adjustment of the threaded member; 
     FIG. 10 is a fragmentary sectional view of the preferred embodiment, illustrating how the threaded member is adjusted by a tool in order to dispose a horizontal bottom surface of the cutter carriage at a horizontal position; 
     FIG. 11 illustrates a relationship between the threaded member and the screw rod of the preferred embodiment after adjustment of the threaded member; and 
     FIG. 12 is a cross-sectional view of the preferred embodiment, illustrating how the threaded member is secured to the cutter carriage. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 5 to  7 , the preferred embodiment of a wood planing machine according to the present invention is shown to include a base  20 , two pairs of hollow posts  30 , two pairs of screw rods  50 ,  51 , a transmission unit  130 , a cutter carriage  40 , and an error reducing unit. 
     As illustrated, the base  20  has four corners  201 ,  202 . 
     The hollow posts  30  are mounted on the base  20  via four tubular seats  21 , and extend uprightly and respectively from the corners  201 ,  202  of the base  20 . Each of the posts  30  is formed with an axial slot  31  for access to an interior thereof. 
     The screw rods  50  are mounted on the corners  201 ,  202  of the base  20  via four bearings (not shown) in such a manner that the screw rods  50  extend rotatably and uprightly therefrom through the posts  30 , respectively. Each of the screw rods  50  has an externally threaded portion  501  that is formed with an external thread. 
     The cutter carriage  40  has four corners  42  mounted respectively, vertically and slidably on the posts  30 , and a horizontal bottom surface  41 . 
     The transmission unit  130  interconnects the screw rods  50  in a conventional manner to permit synchronous rotation of the screw rods  50 . 
     The error reducing unit includes four tubular threaded members  60  (only one is shown in FIGS. 6 and 7) that are secured respectively to the four corners  42  of the carriage  40 , that are disposed respectively within the posts  30  in such a manner that the threaded members  60  are exposed from the axial slots  31  in the posts  30 , and that define axially extending threaded bores  611  (see FIG. 7) respectively engaging the screw rods  50  such that rotation of the screw rods  50  results in vertical movement of the carriage  40  along the posts  30 . 
     Each of the threaded members  60  has an internally threaded portion  613  that defines a respective one of the axially extending threaded bores  611  and that engages the externally threaded portion  501  of the respective one of the screw rods  50 , and a circumferential slot  62  that is formed through a wall of the internally threaded portion  613  so as to divide the internally threaded portion  613  into an upper part  602  and a lower part  601 . The upper part  602  is disposed above the circumferential slot  62 , and has a bottom surface  602 B that defines a top end of the circumferential slot  62 . The lower part  601  is disposed below the circumferential slot  62 , and is formed with a vertically extending threaded bore  63  therethrough. Each of the upper and lower parts  602 ,  601  is formed with an internal thread that engages the external thread of the respective one of the screw rods  50 . The error reducing unit further includes four locking bolts  80  ( only one is shown in FIG. 6) that engage respectively the vertically extending threaded bores  63  in the threaded members  60 , and that press against the bottom surfaces  602 B of the upper parts  602  of the internally threaded portions  613  of the threaded members  60  such that the circumferential slots  62  are enlarged along a vertical direction, in which, the internal threads of the upper parts  602  of the threaded members  60  press upwardly against the external threads of the screw rods  50 , and in which, the internal threads of the lower part  601  of the threaded members  60  press downwardly against the external threads of the screw rods  50  so as to lock the internally threaded portions  613  of the threaded members  60  on the externally threaded portions  501  of the screw rods  50 , thereby arresting inclination of the bottom surface  41  of the carriage  40  when the wood planing machine is in use. 
     In this preferred embodiment, each of the corners  42  of the carriage  40  includes a fixed sleeve  43 , which is disposed around a respective one of the threaded members  60  and which is formed with a vertical row of three bolt extension holes  431 . The upper part  602  of each of the threaded members  60  is formed with two horizontal threaded holes  64 . The wood planing machine of the present invention further includes four pairs of fastener bolts  70 . Each pair of the fastener bolts  70  extend respectively through an adjacent pair of the bolt extension holes  431  in a respective one of the sleeves  43 , and engage respectively the horizontal threaded holes  64  in the respective one of the threaded members  60 , thereby securing the threaded members  60  to the carriage  40 . 
     Referring to FIGS. 8 and 9, when the internally threaded portions  613  of the threaded members  60  engage the externally threaded portion  501  of the screw rods  50 , the threads  614  of the threaded members  60  rest on the threads ( 501 T) of the screw rods  50  due to the weight of the carriage  40 . Thus, clearances  100  are thus formed between the thread ( 501 T) of the screw rod  50  and the thread  614  of the threaded member  60 . 
     Referring to FIGS. 10 and 11, when it is desired to prevent movement of the carriage  40  relative to the screw rods  50 , the locking bolts  80  can be threaded into the threaded bores  63  in the threaded members  60  using an operating tool  90  so that the bolts  80  can press against the bottom surfaces  602 B of the upper parts  602  of the internally threaded portions  613  of the threaded members  60 . At this time, the circumferential slots  62  are enlarged along a vertical direction such that the internal threads  614  of the upper parts  602  of the threaded members  60  press upwardly against the external threads  501 T of the external thread portion  501  of the screw rods  50 , and that the internal threads  614  of-the lower parts  601  of the threaded members  60  press downwardly against the external threads ( 501 T) of the externally threaded portions  501  of the screw rods  50 , thereby locking the internally threaded portions  613  of the threaded members  60  on the externally threaded portions  501  of the screw rods  50  so as to arrest inclination of the bottom surface  41  of the carriage  40  when the wood planing machine is in use. 
     Referring to FIG. 12, each of the threaded members  60  has two spaced-apart curved abutment portions  652  that extend through the axial slot  31  in the respective one of the posts  30  and that abut against an inner wall  432  of the respective one of the sleeves  43  when the fastener bolt  70  extends through the corresponding bolt extension hole  431  in the respective one of the sleeves  43  to engage the corresponding horizontal threaded hole  64  in the respective one of the threaded members  60 . 
     With this invention thus explained, it is apparent that numerous modifications and variations can be made without departing from the scope and spirit of this invention. It is therefore intended that the invention be limited only as indicated in the appended claims.