Note: Descriptions are shown in the official language in which they were submitted.
1.3Y687
2 ¦ TECH IC~L FIELD OF INVENTION
31 This invention relates to machine tools, and particularly, to a
41 mechanism for elevating and lowering a drill press table.
? BACKGROUND ART
9 Drill presses ordinarily utilize a simple split collar and draw
bolt mechanism for clamping the work table to the drill press
11 column. Adjustment of work table height is crude and tedious.
12 Refined mechanisms for achieving adjustment have been suggested.
13 U.S.A. patent to Tautz, No. ?,122,966, typi~ies the present
14 state of that art. Tautz discloses a gear mechanism including
a gear ra~k supported at the side of the drill press column. A
16 worm/ a worm wheel and pinion are all supported heneath the work
17 table in a bearing block cast integrally with the work table.
l8 The worm and worm wheel arrangement prevents gravity from driving
l9 the gear mechanism in reverse whereby the table maintains its
adjusted position even if the column clamp is open. The gear
21 mechanism is a bit complex and, consequently, expensive.
22
23 One difficulty with a mechanism of the type shown in the Tautz
24 patent is that the lifting and lowering of the table is necessar-
26 ily slow due to the inherent high gear ratio between the worm
and worm wheel. A practical problem is that light weight drill
27 presses simply cannot be inexpensively priced if provided with
29 a table elevating mechanism of the type suggested by Tautz. No
practical way has heretofore existed for adding a table elevator
to a drill press, whether of the heavy duty or light weight
. 3l class.
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1~ 113B6~37
1 ¦ OBJ~CTI~ES
2 1
3 I The primary objective of the present invention is to provide a
41 simple mechanism for elevating a drill press table free of the
51 foregoing disadvantages. More particularly, an object of the
61 present invention is to provide an inexpensive mechanism that
7 allows rapid and definitive adjustment of the table height.
8 Another object of the present invention is to provide a mecXanism
9 so simple that it may be attached to an existing drill press
without any modification of the drill press table or any of its
16 I ~ he arts.
29
31
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2 ¦ SUMMARY OF THE INVENTION
3 ¦ In order to achieve the foregoing objectives, I provide a
41 sprocket chain suspended at its top by a simple circular track
and roller arrangement. To the table collar or to another part
6 of the table, I clamp a reversible crank mechanism that includes
7 a horizontal crank shaft mounting a crank arm and a sprocket
8 wheel held in engagement with the sprocket chain. The crank arm
9 is frictionally restrained against rotation. Movement of the
crank arm directly drives the sprocket, thereby causing the
11 sprocket rapidly to move upwardly or downwardly along the chain,
12 correspondingly to elevate or lower the table. In a preferred
13 embodiment, a one way drive or ratchet mechanism is interposed
14 between the crank arm and the friction brake so that the friction
of the brake need not be overcome when the table is elevated,
16 but only when the table is lowered. When the table is elevated,
17 a pawl overrides the ratchet which serves as a backstop. The
18 friction brake is at all times operative to prevent runaway
19 movement.
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` 113E~6~37
i ~RIEF DESCRIPTION OF T~E DRAWINGS
2 ,
. 3 A detailed descript on of *he inventio~ will be made with re-
4 ference to the accompanying drawings wherein like numerals desig-. .
nate corresponding parts in the several figures. These drawings
6 are to scale. .
8 FIGURE 1 is a pictorial-view of a drill press to which is.
9 attached an elevator mechanism incorporating the pxesent--inven-
10 tion.
11 .' ' , , ,
12 FIG. 2 is an enlarged horizontal sectional view through the drill
13 press and attachment, showing the crank mechanism, the view being
14 taken along a plane corresponding to line 2-2 of FIG. 1.
16 FIG. 3 is a segmen~ed vertical sectional view taken along the
17 offset plane corresponding to line 3-3 of FIG. 2.
18
19 FIG. 4 is an elevational view, partly in section, showing the
chain and sprocket structure and taken along the plane indicated .
21 ~y line 4-4 of FIG. 3.
22
24 FIG. 5 is a horizontal sectional view, similar to FIG. 2, but .i
25 showing a modified bracket structure. I
26 FIG. 6 is an axial sectional view through the crank mechanism,
27 and taken along a plane corresponding to line 6-6 of FIG. 5.
28 I
29 FIG. 7 is a side elevational view of the chain and sprocket struc- ,
~` 30 ture, and taken along a plane corresponding ~o line 7-7 of FIG. 6. I
~i~ 31 ~` 32 .
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1 ¦ FIG. 8 is a sectional view of the attachment bracket and taken
2 along a plane corresponding to line 8-8 of FIG. 5.
4 ¦ FIG. 9 is an axial sectional view similar to FIG. 6, but
5 I showing a modified crank mechanism in which the crank arm is
r-~ y ~on e~te~ to a brake plate.
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1131361~
1 D~TAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
3 The following detailed description is of the bes~ ~presently con- -
4 templated modes of carrying out the invention. This description
is not to be taken in a limiting sense, but is made-merely for
6 purposes of illustrating the general principles of the invention,
7 since the scope of the invention is best defined by the appended
8 claims.
Structural and opérational characteristics attributed to forms
11 of the invention first described, shall also be attributed to
12 forms later described, unless such characteristics are obviously
13 inapplicable or lLnless specific exception is made.
14
A conventional drill press 10 shown in FIG. 1 has a table 12
16 clamped to the drill press column 14 by the aid of the usual
17 split collar 16 and draw bolt 18. The table 12 is made as a
18 casting, there being bracket arms 20 (FIG. 2) joining the collar
19 to the work part 22 of the table 12. As used hereinafter, the
word "table" refers to the entire part supported on the drill
21 press column.
22
23 The table 12 is guided for vertical movement by the fitted re-
24 lationship of the collar 16 and the column 14. The table 12
rides up and down along a sprocket chain 240 The sprocket chain
Z6 24 is suspended from a two part bracket 26 (FIG. 3) clamped to
27 the top of the drill press column 14. Companion parts of the
28 bracket 26 provide a plate 28 in which a circular raceway or
29 channel 30 is formed. A roller bearing 32 rides in the channel
30. The upper end of the chain 24 is attached to the roller
31 bearing 32 by the aid of a C-shaped bracket 34 that encompasses
32 the edge of the plate 28. The bracket 34 locates the chain 24
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1 ¦ in alignment with the bearing 32 to maintain a proper tracking
2 ¦ relationship. The' chain 24 extends vertically in spaced Ie-
3 ¦ lationship to the drill press column 14.
4 l
5 ¦ The table 12 is connected to the sprocket chain 24 by a sprocket-
6 ¦ wheel 36. The sprocket wheel is rotatably mounted on one side of
71 a supporting,block or bracket 38 attached to the table. The
81 sprocket wheel 36 has a hub 40 secured to one end o~ a shaft 42
9 centrally supported in a horizontal bearing aperture of the
block 38. The other end of the shaft cooperates with mechanisms
11 to be described hereinafter_ The block or bracket 38 is affixed
12 to the table 12 by the aid of upper-and lower jaws or arms 46
13 and 47. These jaws extend above and below the sprocket wheel 36
14 on one side of the block 38. The jaws project beyond the sprocket _
wheel 36 and respectively overlie the upper and lower end surfaces
'16 of the mounting collar 16. Set screws 48 and 49 secure the jaws
17 to the collar. The jaws 46 and 47 are sized and proportioned so
18 that the axis of the sprocket wheel 36 is skew to the chain, and
19 so that the sprocket wheel 36 is spaced from the column 14 to
'20 engage the sprocket chain 24. The chain 24 passes through
21 aligned apertures 50 and 51 in the upper and lower attachment
22 jaws 46 and 47.
23
24 Normally, the draw bolt 18 secures the table to the column 14.
If adjustment of t'he table height is desired, the draw bolt is
26 released. The weight of the table is transmitted through the
27 collar 16 and shaft 42, and tends to cause the sprocket wheel 36
28 to rotate downwardly on the chain 24. Ho~ever, such movement is
29 resisted by a friction brake structure. The brake structure in-
~0 cludes a friction plate 54, a brake plate 56, a brake spring 58
31 and a stop nut 60. The stop nut 60 is threadedly mounted on the
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1 end of a hub 62 formed on the outside of the block or bràcket 382 remote from the sprocket wheel 36. The frictlon plate 54 sur-
3 rounds the hub and is adhered by cement, rivets or other means
4 to the outer face of the bracket 38. The brake plate similarly
surrounds the hub 62 and is slideable thereon. A brake spring
6 58 also surrounds the hub and is interposed between the brake
7 plate 56 and the stop nut 60 thus to move the brake plate 56 into
8 firm engagement with the friction plate 54. The brake plate 56
9 is accordingly restrained from rotation.
11 The shaft 42 is connected to the brake plate 56 so that the
12 shaft 42 and sprocket 40 are likewise restrained from rotation.
13 For this purpose, a crank body is attached, as by a set screw
14 64, to the outer end of the shaft 42. The crank body has an
outboard block 66 extending over the stop nut 60. The block
16 provides an elongated aperture 68 paralleling the shaft 42.
17 Guided in the aperture 68 is a hollow pawl 70 urged, in turn, by
18 a compression spring 72 to engage ratchet teeth 74 that crown the
19 brake plate 56. A key and pin or other means (not shown~ main-
tain the pawl 70 in suitable orientation for engagement with the
21 ratchet teeth 74. Torque tending to rotate the sprocket wheel
22 36 downwardly on the chain 24 tends to rotate the crank body
23 and pawl 70 in a direction to lock against the ratchet teeth 74.
24
In order to move the shaft 42 to cause the sprocket 40 to climb
26 up or descend down the chain 24, correspondingly to move the
27 table, the crank body is rotated by hand. For this purpose,
28 a handle 78 (see also FIG. 2) is provided. The handle 78 and
29 Grank body together form a crank arm for the shaft 42. The
h~dle 78 extends through an aperture 80 in the crank body and
31 is secured by a set screw 82. Movement of the handle 78 and
32 crank body in one direction causes the sprocket wheel 36 to
~^ climb up the sprocket chain as the pawl 70 ratchets over the
3~
1 restrained brake plate 56. Movement of the handle 78 and
2 crank body in the opposite direction forces the brake plate
3 56 to move along the friction plate 54. The brake plate 56 is,
4 at all times, yieldingly restrained.
Movement of the crank handle 78 achieves very rapid adjustment
6 of the table, since the drive between the sprocket wheel 36 and
7 the crank is direct and unencumbered with any additional stage of
gearing. An exact position of the table can readily be obtained,
9 since if the discrete ratcheting movement overshoots a desired
position, it is merely necessary to force the ratchet teeth in
11 the re~erse direction.
12 '
13 The angular orientation of the table about the column 14 can be
adjusted without requiring any special operations. Thus, as the
table is rotated, the chain follows along its overhead channel
1~ 30. -
17
18 To ensure continuous engagement of the chain with the sprocket
19 ¦ wheel, a chain guide 84 is provided (FIG. 4) that is attached to
an embossment on the inside of the block or bracket 38. The
21 guide 84 defines with the sprocket wheel 36, a narrow channel for
22 the chain so that it at all times engages the sprocket wheel 36.
23 A weight 86 (FIG. 1) is attached to the lower end of the chain
24 which stabilizes it and,prevents it from whipping about.
~5
~6 After the table is adjusted, the draw bolt 18 preferrably is re-
Z7 tightened so that undue stress need not be absorbed by the chain
28 during work operations.
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1 ¦ No part of the drill press need be modified or discarded for
2 ¦ purposes of installation of-the drill-press table elevator.
3 ¦ Installation of the elevator is relatively simple, requiring
41 the placement of the upper chain suspension bracket 26 and the
n acket 3~.
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113~16B7
1 DESCRIPTION OF FIRST ALTERNATIVE EMBODIMENT
2 . ~ .
3 In the form of the invention shown in FIGS. ~ through 8, a
4 bracket 100 rotatably mounts a sprocket wheel 102 as well as a
guide 104 (FIG. 7) for the sprocket chain 106. As in the pre-
6 vious form, the bracket 100 carries a friction plate 108 and a
7 ratchet crowned brake plate 110.
9 The bracket 100 in the present form is attached not to the
collar 112 of the drill press table, but instead to one of the
11 ribs or arms 114 radiati-ng therefrom. For this purpose, a clamp
12 116 is attached to the rib 114 (FIG. 8) as by providing a
13 channel 118 for receiving the rib. Set screws 120 secure the
14 clamp 116. The clamp 116 is connected to the sprocket bearing
bracket 100 by the aid of a bar 122. Slots 130 and 132 (FIG. 5)
16 in the bar allow passage of attachment bolts 126 and 128 that
17 respectively engage the clamp 116 and the bracket 100 from
18 below (see also FIG. 6)~ The bar adequately offsets the elevator
assembly from beneath the drill press table. The slots 130 and
132 in the bar allow the sprocket wheel bracket 100 to be moved
22 angularly and linearly to align the sprocket whee-l 102 with the
23 suspended sprocket chain.
24 Although the alternative embodiment includes parts identical to
those of the preferred embodiment, various changes of components
26 can be made. For example, the brake plate, instead of having l,
27 ratchet teeth formed as a crown, could be formed at the edge for
28 a less compact arrangement. Furthermore, one way drive mechanisms
29 other than ratchet mechanisms could be used.
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1 SCRIPTION ~P SECO~D ~LTE~NATIVE EM~ODIMENT
3 In the form of the invention shown in FIG. 9, a bracket 150
4 similar to the bracket 100 of the previous form is attached to
the drill press table by suitable means. ~he bracket 150
6 rotatably supports a crank shaft 152. ~ sprocket wheel 154 is
7 mounted on one end of the crank shaft 152 for engagement with
8 the sprocket chain 156 as before. The other end of the crank
9 shaft is angled to form a crank arm 158 and handle 160.
11 A~gular movement of the crank mechanism is restrained by a
12 friction brake structure that includes a friction plate 162, a
13 brake plate 164, a brake spring 166 and a stop nut 168, all
14 similar to the brake structure of the previous forms. In the
present instance, howe~er, the crank arm 158 is directly, rather
16 than indirectly, coupled to the brake plate 164. For this pur-
17 po~e, the crank arm 158 carries a drive pin 170 that enters a
18 peripheral slot or recess 172 in the brake plate 164.
19
Downward adjustment of the table is accomplished by moving the
21 crank mechanism in one direction. As in the previous forms,
22 gravity assists in overcoming the friction force of the brake
23 structure. Upward adjustment of the table is accomplished by
24 moving the crank mechanism in the other direction. In the pre-
sent instance, no one way drive mechanism is provided; hence,
26 both gravity and the friction force must be overcome. To com-
27 pensate for the increased effort required for upward movement of
28 the table, the crank arm 158 may be lengthened. The structure,
29 however, retains major advantages of the forms previously des-
cribed by allowing rapid adjustment of table height.
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