Wood planing machine

A wood planing machine includes a machine housing with two upright side walls, and a cutter unit mounted between the side walls to extend in a transverse direction. A workpiece support bed is movably disposed in the machine housing between the side walls and below the cutter unit. The bed is movable uprightly relative to the cutter unit so as to define a workpiece passage therebetween. A holding seat is suspended in the machine housing below the bed and between the side walls. The holding seat includes a tubular body formed with an upright passage therethrough, and a radial pinion-mounting hole in communication with the passage. A height adjustment mechanism includes an upright coupling member secured to a bottom side of the bed, and a vertical rack that extends between upper and lower ends of the coupling member. The coupling member extends slidably through the passage of the holding seat. A drive shaft has a first coupling end mounted rotatably on the tubular body and extending across the pinion-mounting hole. A turning wheel unit is mounted on the machine housing and is coupled to a second coupling end of the drive shaft. A pinion is disposed in the pinion-mounting hole and is fixed on the first coupling end of the drive shaft for meshing with the vertical rack.

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 a height adjustment mechanism that is 
adapted to be operated externally of a machine body with ease. 
2. Description of the Related Art 
Referring to FIGS. 1 and 2, a conventional wood planing machine 10 is shown 
to include a machine base 11, an upper housing 13, and cutting and feed 
rollers 14. 
As illustrated, the machine base 11 has a bed with opposite end portions, a 
pair of upright threaded rods 23 mounted rotatably on the opposite end 
portions of the bed, and a pair of vertical side walls 12 mounted on the 
opposite end portions of the bed. The side walls 12 are formed with front 
and rear pairs of aligned vertically extending slots 121. 
The upper housing 13 is disposed between the side walls 12 above the bed. 
The upper housing 13 has front and rear portions provided respectively 
with an opposite pair of insert pieces 21 which engage a corresponding one 
of the front and rear pairs of vertically extending slots 121 to mount 
slidably the upper housing 13 on the side walls 12. The upper housing 13 
further has opposite end portions formed with a pair of vertically 
extending screw holes. The threaded rods 23 extend threadedly and 
respectively through the screw holes, and are rotatable on the bed so as 
to raise or lower the upper housing 13 to a desired position relative to 
the bed. 
The cutter and feed rollers 14 are mounted rotatably on the upper housing 
13, and are rotatable about parallel horizontal axes. 
The front and rear sides of the housing 13 are formed with vertical bores 
for extension of front and rear pairs of upright pillars (not visible) 
mounted on the machine bed. 
The front and rear insert pieces 21 are formed with a respective horizontal 
bore therethrough which receives a respective horizontal mounting shaft 
that is aligned with a corresponding one of the front and rear pairs of 
vertically extending slots 121. The mounting shaft has opposite first and 
second end portions which extend respectively into the corresponding one 
of the slots 121 and which has a respective clamp piece 22 provided 
thereon. 
The clamp pieces 22 are provided with externally operable locking knobs 221 
respectively for forcing the clamp pieces 22 against the side walls 12 to 
lock the upper housing 13 at the desired position on the side walls 12. 
The drawbacks of the aforementioned wood planing machine 10 are as follows: 
1. The upper housing 13 can be positioned at a desired height on the 
machine base 11 due to the threaded engagement thereof with the threaded 
rods 23. When the wood planing machine 10 is in operation, the upper 
housing 13 is subjected to vertical forces which are applied to the 
threaded engagement between the threaded rods 23 and the upper housing 13, 
thereby resulting in the possibility of damage to the screw threads on the 
threaded rods 23 or in the screw holes. 
2. The vertical bores in the upper housing 13 must match the pillars on the 
bed so as to ensure smooth sliding movement of the upper housing 13 on the 
pillars. However, when the wood planing machine 10 is in operation, the 
upper housing 13 may be subjected to uneven lateral forces which are 
transmitted to the pillars. As such, bending of the pillars may result to 
prevent future adjustment of the height of the upper housing 13. 
3. Referring to FIG. 3, the conventional wood planing machine 10 further 
includes a rotating shaft 24 disposed between the side walls 12 and 
operably connected to the threaded rods 23, and a transmission shaft 26 
with a transmission gear 261 mounted co-axially on the rotating shaft 24. 
A turning wheel unit is provided on one of the side walls 12, and includes 
a turning wheel 25, and a wheel axle 27 having a proximate end secured to 
the turning wheel 25 and a distal teethed end 271. When adjusting the 
height of the upper housing 13 relative to the bed, the turning wheel 25 
is pressed against biasing action of a spring 28 so as to mesh the teethed 
end 271 of the wheel axle 27 with the transmission gear 261. This action 
inconveniences the user of the conventional wood planing machine. 
SUMMARY OF THE INVENTION 
Therefore, the object of this invention is to provide a wood planing 
machine which is clear of the aforementioned drawbacks that are associated 
with the use of the conventional wood planing machine. 
Accordingly, a wood planing machine of the present invention includes a 
machine housing, a cutter unit, a workpiece support bed, a holding seat, 
and a height adjustment mechanism. The machine housing has upright left 
and right side walls that are spaced apart from each other in a transverse 
direction. The cutter unit is mounted to the machine housing, and extends 
in the transverse direction between the left and right side walls. The 
workpiece support bed is movably disposed in the machine housing between 
the left and right side walls and below the cutter unit. The workpiece 
support bed has top and bottom sides and is movable uprightly relative to 
the cutter unit so as to define a workpiece passage between the top side 
of the bed and the cutter unit. The holding seat is suspended in the 
machine housing below the workpiece support bed and between the left and 
right side walls. The holding seat includes a tubular body formed with an 
upright passage therethrough. The tubular body is further formed with a 
radial pinion-mounting hole in communication with the passage. The height 
adjustment mechanism includes an upright coupling member having an upper 
end secured to the bottom side of the workpiece support bed, a lower end, 
and a vertical rack that extends between the upper and lower ends. The 
coupling member extends slidably through the passage of the holding seat 
with the vertical rack registering with the pinion-mounting hole. A drive 
shaft has a first coupling end that is mounted rotatably on the tubular 
body and that extends across the pinion-mounting hole in the transverse 
direction, and a second coupling end. A turning wheel unit is mounted on 
the machine housing and is coupled to the second coupling end of the drive 
shaft for driving the drive shaft to rotate axially. A pinion is disposed 
in the pinion-mounting hole, and is mounted on the first coupling end of 
the drive shaft for co-rotation therewith. The pinion meshes with the 
vertical rack to move the workpiece support bed relative to the cutter 
unit when the drive shaft rotates axially.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIGS. 4, 5, 6 and 7, the preferred embodiment of a wood 
planing machine of the present invention is shown to include a machine 
housing 80, a cutter unit 84, a workpiece support bed 83, a holding seat 
40, and a height adjustment mechanism 60. 
As illustrated, the machine housing 80 has upright left and right side 
walls 81,82 that are spaced apart from each other in a transverse 
direction. 
The cutter unit 84 is mounted on the machine housing 80 in a conventional 
manner, and extends in the transverse direction between the left and right 
side walls 81,82. 
The workpiece support bed 83 is movably disposed in the machine housing 80 
between the left and right side walls 81,82 and below the cutter unit 84. 
The support bed 83 has top and bottom sides, and is movable uprightly 
relative to the cutter unit 84 so as to define a workpiece passage between 
the top side of the support bed 83 and the cutter unit 84. 
The holding seat 40 is suspended in the machine housing 80 below the 
support bed 83 and between the left and right side walls 81,82. The 
holding seat 40 includes a tubular body 41 formed with an upright passage 
410 therethrough, and a rectangular radial projection 44 integrally formed 
with the tubular body 41 and which defines a radial pinion-mounting hole 
441 in communication with the upright passage 410. A cover member 440 is 
detachably mounted on the radial projection 44 to shield the 
pinion-mounting hole 441. 
The height adjustment mechanism 60 includes an upright coupling member 30, 
a drive shaft 50, a turning wheel unit, and a pinion 51. The coupling 
member 30 is in a form of a tube, and has an upper end 301 secured to the 
bottom side of the bed 83, a lower end 302, and a vertical rack 32 that 
extends between the upper and lower ends 301,302. The coupling member 30 
extends slidably through the passage 410 of the tubular body 41 with the 
vertical rack 32 registering with the pinion-mounting hole 441. The drive 
shaft 50 has a first coupling end 503 that is mounted rotatably on the 
tubular body 41 and that extends across the pinion-mounting hole 441 in 
the transverse direction, and a second coupling end 502. The turning wheel 
unit is mounted on the machine housing 80, and is coupled to the second 
coupling end 502 of the drive shaft 50 for driving the drive shaft 50 to 
rotate axially. The pinion 51 is disposed in the pinion-mounting hole 441 
of the radial projection 44. A fastener screw 52 extends through the 
pinion 51 and is mounted on the first coupling end 503 of the drive shaft 
50 to ensure co-rotation of the pinion 51 with the drive shaft 50. The 
pinion 51 meshes with the vertical rack 32 to move the support bed 83 
relative to the cutter unit 84 when the drive shaft 50 rotates axially. 
In the preferred embodiment, the tubular body 41 has a pair of connecting 
portions 42 on opposite sides of the pinion-mounting hole 441. The holding 
seat 40 further includes a pair of bracing rods 43 that extend through the 
connecting portions 42 of the tubular body 41 and that have opposite ends 
secured to the left and right side walls 81,82, respectively. Preferably, 
the second coupling end 502 of the drive shaft 50 has a worm gear 54 
secured thereon by means of a key 53. The turning wheel unit includes a 
transmission shaft 65, and a mounting member 63 fixed on the left side 
wall 81 for mounting the transmission shaft 65 such that the transmission 
shaft 65 on the left side wall 81 is rotatable axially. The transmission 
shaft 65 has a first end 651 provided with a turning wheel 62, and a 
second end 652 provided with a worm 61 that meshes with the worm gear 54. 
The coupling member 30 has an outer wall surface formed with a vertically 
extending mounting groove 31. The vertical rack 32 is mounted securely to 
the coupling member 30 in the mounting groove 31 and projects radially 
from the outer wall surface of the coupling member 30. The tubular body 41 
has an inner wall surface formed with a vertically extending slide groove 
411. The vertical rack 32 extends slidably into the slide groove 411, 
thereby guiding movement of the coupling member 30 relative to the holding 
seat 40. 
The preferred embodiment further includes a locking mechanism provided on 
the tubular body 41 opposite to the radial projection 44 and operable to 
result in tight frictional engagement between the tubular body 41 and the 
coupling member 30 for retaining the support bed 83 at a desired position 
relative to the cutter unit 84. The tubular body 41 is further formed with 
a radial opening 412 in communication with the passage 410, and has 
opposite edges 412E. The locking mechanism includes a pair of clamping 
plates 413, a parallel pair of lug plates 45, and a locking shaft 70. Each 
of the clamping plates 413 has a connecting end 413C that is connected to 
a respective one of the opposite edges 412E of the radial opening 412, and 
a distal end 413D that forms a clearance 451 (see FIG. 9) with the distal 
end 413D of the other one of the clamping plates 413. Each of the lug 
plates 455,453 extends from the distal end 413D of a respective one of the 
clamping plates 413 away from the tubular body 41. One of the lug plates 
455 is formed with a through-hole. The other one of the lug plates 453 is 
provided with a nut 46 that is formed with an internally threaded screw 
hole 461. 
As best shown in FIGS. 9 and 10, the locking shaft 70 has a 
diameter-reduced threaded end portion 71 that extends through the 
through-hole in the lug plate 455 and that engages the screw hole 461 in 
the nut 46. The locking shaft 70 is rotatable axially to bring the lug 
plates 455,453 closer to each other in order to enable the clamping plates 
413 to contact tightly the coupling member 30. The locking shaft 70 
further has an operating end portion 72 with a polygonal cross-section. 
The operating end portion 72 of the locking shaft 70 extends rotatably 
through the left side wall 81 so that the locking shaft 70 is operable 
externally of the side wall 81. 
Referring to FIGS. 10 and 11, when it is desired to adjust the height of 
the workpiece support bed 83 relative the cutting unit 84, the locking 
shaft 70 is loosened with the use of a tool 75 (see FIG. 5) so as to widen 
the clearance 451. Under this condition, the workpiece support bed 83 can 
be lowered or raised relative to the cutting unit 84 via turning of the 
turning wheel 62, which action consequently rotates the drive shaft 50 to 
move the coupling member 30 along the upright passage of the tubular body 
41. 
FIG. 12 illustrates a state where the coupling member 30 is locked in the 
tubular body 41 due to a tightening action on the locking shaft 70. 
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 this invention 
be limited only as indicated in the appended claims.