Machine tools abstract
A vertical/horizontal spindle head for machine tools having a main
transmission shaft with a first bevel gear secured thereon, a lower
rotatable housing having a bevel gear axle secured therein, an upper
seat having a push/pull apparatus for axially moving the lower rotatable
housing relative to the upper seat, a main shaft having a second
bevel gear secured thereon, third and fourth bevel gears coaxially
arranged on the bevel gear axle, and a curved coupling between the
upper seat and the lower rotatable housing. Between the third and
fourth bevel gears are springs to move the third bevel gear axially
and maintain it in engagement with the first bevel gear. A slidable
spline device is provided between the third bevel gear and the bevel
gear axle. The slidable spline device is disengaged in a first position
where the curved coupling is coupled and is engaged in a second
position when the lower rotatable housing is pushed away from the
upper seat by the push/pull apparatus and the curved coupling is
uncoupled. In the first position, the main transmission shaft can
rotate the main shaft through the first, third, fourth and second
bevel gears. In the second position, the lower rotatable housing
can be rotated to a desired angular position by the main transmission
shaft, through the first bevel gear, the third bevel gear and the
slidable spline device.
Machine tools claims
What is claimed is:
1. A vertical/horizontal spindle head for machine tools comprising:
a main transmission shaft pivotally arranged on a body of a machine
tool and having two ends, one end being co-axially secured to a
first bevel gear thereon;
a lower rotatable housing including a main shaft, said main shaft
being circumferentially and coaxially secured with a second bevel
gear;
a bevel gear axle firmly secured within said lower rotatable housing
and forming angles respectively with said main transmission shaft
and said main shaft;
a third bevel gear and a fourth bevel gear coaxially arranged on
said bevel gear axle to be rotated together and being biased by
a plurality of compressed springs therebetween so that said third
bevel gear can axially slide on said bevel gear axle, while maintaining
an engagement of the third bevel gear with the first bevel gear;
an upper seat secured on the body of the machine tool concentrically
with the bevel gear axle;
a push/pull apparatus for pushing/pulling the lower rotatable housing
to move in an axial direction of the bevel gear axle between a first
position where the lower rotatable housing is closest to the upper
seat and a second position where the lower rotatable housing is
furthest from the upper seat, said push/pull apparatus being concentric
with the bevel gear axle and arranged on the upper seat;
a curved coupling including an upper curved ring and a lower curved
ring respectively positioned on said upper seat and said lower rotatable
housing, said upper and lower curved rings being coupled and uncoupled
in said first and second positions respectively;
a slidable spline device disposed between said third bevel gear
and said bevel gear axle, said slidable spline device being disengaged
and engaged when the lower rotatable housing is respectively in
the first and second positions;
wherein said push/pull apparatus for pushing/pulling the lower
housing comprises a hydraulic device comprising:
an annular hydraulic cylinder concentric with the bevel gear axle
and formed on said upper seat;
an annular piston movably arranged within said annular hydraulic
cylinder;
an upper gland ring secured at an opening of said hydraulic cylinder;
a lower gland ring concentrically arranged with the bevel gear
axle;
a supporting ring disposed between said upper and lower gland rings;
and
a plurality of supporting bolts having two ends, one end being
secured to said lower gland ring and the other end being secured
to said piston for mechanically connecting the lower rotatable housing
to the piston.
2. The vertical/horizontal spindle head for machine tools as claimed
in claim 1 wherein said supporting ring is formed with an annular
groove, and said upper gland ring is formed with at least one through
hole at a location corresponding to the annular groove of the supporting
ring when the lower rotatable housing is in the first position,
a steel ball in said through hole biased by a compressed spring
and partially protruding out of the through hole.
3. The vertical/horizontal spindle head for machine tools as claimed
in claim 1 wherein the bevel gear axle forms angles of 135.degree.
and 45.degree. with said main transmission shaft and said main shaft
respectively.
4. The vertical/horizontal spindle head for machine tools as claimed
in claim 1 wherein said hydraulic cylinder and said piston are
sealed by oil seals therebetween.
Machine tools description
FIELD OF THE INVENTION
The present invention relates to a vertical/horizontal spindle
head for machine tools; specifically to one that utilizes a push/pull
apparatus and a slidable spline device, in association with the
rotation of a main transmission shaft, to change the spindle head
to either a vertical or a horizontal position.
BACKGROUND OF THE INVENTION
"The expression vertical/horizontal spindle head for machine
tools" refers to a spindle head for machine tools that is able
to change to either a vertical or horizontal position relative to
a transmission shaft on facilitate a vertical and horizontal machining
operation a work piece as required. To associate with an index rotatable
work table, the vertical/horizontal machining center can cut at
five faces of a workpiece in one setting. Therefore, a milling machine
equipped with a vertical/horizontal spindle head will considerably
increase its added value.
As shown in FIGS. 1 and 2 a conventional vertical/horizontal spindle
head requires the operator to manually loosen the connection bolts
in order to rotate the spindle head to a desired position. Such
a conventional spindle head not only is time-consuming in operation,
but also is not compatible with CNC automatic machine tools.
In order to be compatible with CNC machine tools, a vertical/horizontal
spindle head must be able to automatically change its angular positions.
The most commonly known manner is to loosen a curved coupling disposed
on a 45.degree. inclined surface, and then rotate the spindle head
to a desired angular position by means of a hydraulic motor a plurality
of and gears disposed on the 45.degree. inclined surface (see FIG.
3). Then, the spindle head is pulled by a hydraulic cylinder for
tightening and engaging the curved coupling. Such a design is undesirable
because it requires an additional hydraulic motor to drive the spindle
head. This not only will increase the cost of the machine but also
because of the limited space available, it is difficult to fit the
hydraulic motor into the machine.
U.S. Pat. No. 4841795 issued to Gioacchino Obrietan in 1989 discloses
a "Double-Rotatable Universal Head for Machine Tools"
(see FIG. 4). The Obrietan invention utilizes a head carrier interposed
between the spindle head and a slide in order to transmit torque
from the machine tool drive shaft to the spindle. However, before
commencing with the rotation, the cast piece and the drive shaft
must be secured. In addition, because of the force undertaken by
the spindle under this configuration, this may lead to premature
fatigue of the spindle bearing. Since the angular positions of the
spindle head of the Obrietan invention are secured through hydraulic
force instead of a curved coupling, the accuracy of the positions
is difficult to maintain.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a dependable and
structurally simple vertical/horizontal spindle head that utilizes
the rotation of a main transmission shaft in association with a
slidable spline device to rotate the spindle head which is advantageous
in providing smooth operation at relatively low cost and capable
of installation in the limited space available in machine tools.
It is also an object of the present invention to provide a vertical/horizontal
spindle head able to accurately rotate to the desired angular positions.
It is yet another object of the present invention to provide a
vertical/horizontal spindle head so that bevel gears are not disengaged
from one another during the changing of the angular positions of
the spindle head to avoid wear and tear on the gears or problems
related to gear clearance.
The spindle head of the present invention comprises a main transmission
shaft, a first bevel gear, a lower rotatable housing, an upper seat,
a bevel gear axle, a main shaft, a second bevel gear, a third bevel
gear, a fourth bevel gear, a curved coupling, and a push/pull apparatus.
The first bevel gear is coaxially secured on one end of the main
transmission shaft. The main shaft is circumferentially and co-axially
secured with the second bevel gear and is pivotally arranged within
the lower rotatable housing. The bevel gear axle is firmly secured
within the lower rotatable housing and forms, an angle of 135.degree.
with the main transmission shaft and an angle of 45.degree. with
the main shaft, The third and fourth bevel gears are rotatably and
co-axially arranged on the bevel gear axle and are biased by a compressed
spring disposed therebetween, so that the third and fourth bevel
gears respectively engage with the corresponding first and second
bevel gears. The upper seat is mounted on a body of the machine
tool and is concentric with the bevel gear axle. The push/pull apparatus
is arranged on the upper seat for pushing/pulling the lower rotatable
housing in an axial direction of the bevel gear axle, between first
and second positions. The curved coupling includes an upper and
lower curved rings respectively mounted on the upper seat and the
lower rotatable housing. The upper and lower curved rings engage
with or disengage from each other when the lower rotatable housing
is in the first or second position. A slidable spline device is
provided between the third bevel gear and the bevel gear axle. The
slide spline device is disengaged or engaged when the lower rotatable
housing is in the first or the second position. When the push/pull
apparatus pulls the lower rotatable housing into the first position,
a rotational force can be transferred, through the main transmission
shaft, the first, third, fourth and second bevel gears to drive
the main shaft in rotation. When the push/pull apparatus pushes
the lower rotatable housing into the second position, the curved
coupling is disengaged, the third bevel gear is maintained in contact
with the first bevel gear by means of the biased spring disposed
between the third and fourth bevel gears, and the slidable spline
device is so engaged that the bevel gear axle engages the third
bevel gear, whereby the lower rotatable housing can be changed to
a vertical or horizontal position by using the rotational force
through the main transmission shaft.
These and other objects, advantages and features of the present
invention will become apparent to those skilled in the art from
the following detailed description of the preferred embodiment,
when read in light of the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view showing a conventional and manually
operated vertical/horizontal dual spindle head in which the main
shaft thereof is in a vertical position;
FIG. 2 is another schematic view showing a conventional and manually
operated vertical/horizontal spindle head in which the main shaft
thereof is in a horizontal position;
FIG. 3 is a perspective view showing a conventional automatic vertical/horizontal
spindle head;
FIG. 4 is a sectionally schematic view of U.S. Pat. No. 4841795.
FIG. 5 is a schematic, longitudinal sectional view of one preferred
embodiment of a vertical/horizontal dual spindle head in accordance
with the present invention showing that the lower rotatable housing
is pulled by the hydraulic piston to the first position where the
lower rotatable housing is closest to the upper seat, the curved
coupling being engaged and the slidable spline device being disengaged;
FIG. 6 is another schematic, longitudinal sectional view of the
preferred embodiment of the present invention showing that the lower
rotatable housing pushed by the hydraulic piston to the second position
where the lower rotatable housing is farthest from the upper seat,
the curved coupling being disengaged and the slidable spline device
being engaged; and
FIG. 7 is a schematic, longitudinal sectional view similar to that
of FIG. 6 except that the lower rotatable housing has rotated to
the horizontal position and returned to the first position.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 5 and 6 the vertical/horizontal spindle head
(1) of the subject invention mainly includes a main transmission
shaft (11), a first bevel gear (12), a lower rotatable housing (2),
a bevel gear axle (21), an upper seat (3), a curved coupling (4),
a main shaft (5), a second bevel gear (51), a third bevel gear (6)
and a fourth bevel gear (7), a slidable spline device (61), a compressed
spring (71), and a push/pull apparatus (8) for pushing/pulling lower
housing. The main transmission shaft (11) includes two ends and
is pivotally arranged within a body of a machine tool (F). The first
bevel gear (12) is coaxially and firmly secured on one end of the
main transmission shaft (11).
The main shaft (5) is pivoted within the lower rotatable housing
(2). The second bevel gear (51) is coaxially secured on the main
shaft (5). The bevel gear axle (21) is firmly secured within the
lower rotatable housing (2) to form angles of 135.degree. and 45.degree.
with said main transmission shaft (11) and said main shaft (5) respectively.
The third and fourth bevel gears (6)(7) are co-axially and circumferentially
mounted on the bevel gear axle (21) with bearings (B). The third
and fourth bevel gears (6)(7) rotate together and are biased by
the compressed spring (71) disposed therebetween to enable the third
bevel gear (6) to slide away from said fourth bevel gear (7) in
the axial direction of said bevel gear axle (21), so that the third
bevel gear (6) is fourth bevel gear (7) respectively remain in engagement
with the corresponding first and second bevel gears (12) (51).
The upper seat (3) is securely positioned on the body of the machine
tool (F) is concentric with the bevel gear axle (21). The push/pull
apparatus (8) for pushing/pulling the lower housing (2), preferably
a hydraulic apparatus, is provided on the upper seat (3), and includes
an annular hydraulic cylinder (81), an annular piston (82), an upper
gland ring (83), a supporting ring (84), a lower gland ring (85),
and a plurality of supporting bolts (86). The annular hydraulic
device (81) is concentric with the bevel gear axle (21) and is formed
on the upper seat (3).
The annular piston (82) is slidably engaged in the annular hydraulic
cylinder (81) and is movable in the axial direction of the bevel
gear axle (21).
The upper gland ring (83) is positioned at an opening of said hydraulic
cylinder (81) to prevent excessive outward movement of the piston
(82). The lower gland ring (85) is concentric with the bevel gear
axle (21). The supporting ring (84) is concentric with the bevel
gear axle (21) and is arranged between the piston (82) and the lower
gland ring (85). One end of each of the supporting bolts (86) is
firmly secured on the lower gland ring (85) and the other end is
firmly secured on the piston (82) thereby mechanically connecting
the lower rotatable housing (2) to the piston (82). Oil seals (S)
may be provided between the piston (82) and said annular hydraulic
cylinder (81) to prevent oil leakage. The hydraulic push/pull apparatus
(8), under the operation of a hydraulic system, is able to pull
the lower rotatable housing (2) toward the upper seat (3) in the
axial direction of the bevel gear axle (21) to a first position
where the lower rotatable housing (2) is closest to the upper seat
(3) (see FIG. 5). Alternatively, the push/pull apparatus (8) may
also push the lower rotatable housing (2) away from the upper seat
(3) in the axial direction of the bevel gear axle (21) to a second
position where the lower rotatable housing (2) is farthest from
the upper seat (3) (see FIG. 6). The annular supporting ring (84)
is formed with an annular groove (841). When in the first position,
the upper gland ring (83) is formed with at least one through hole
(831) at the place corresponding to the annular groove (841) of
the annular supporting ring (84). The through hole (831) receives
a compressed spring (832) and a steel ball (833), in which the steel
ball (833) is biased by the compressed spring (832) and partially
protrudes out of the through holes (831). In association with the
annular grooves (841) of the annular supporting ring (84), the steel
ball (833) maintains the lower rotatable housing (2) in the first
position.
The curved coupling (4) includes an upper curved ring (41) and
a lower curved ring (42) correspondingly positioned on the upper
seat (3) and the lower rotatable housing (2) respectively. The upper
and lower curved rings (41) (42) are coupled and uncoupled as the
lower rotatable housing (2) is in the first and second positions
respectively.
The slidable spline device (61) is disposed between the third bevel
gear (6) and the bevel gear axle (21). When the lower rotatable
housing (2) is in the first position, the slidable spline device
(61) is disengaged such that the third bevel gear (6) is freely
rotatable about the bevel gear axle (21). When the lower rotatable
housing (2) is in the second position, the slidable spline device
(61) is engaged such that the bevel gear axle (21) rotates together
with the third bevel gear (6).
As can be seen from FIG. 5 when the lower rotatable housing (2)
is located at the first position, the hydraulic cylinder (81) maintains
the piston (82) in the first position. The upper and lower curved
ring (41) (42) of the curved coupling (4) are engaged. The third
and fourth bevel gears (6) (7) are respectively engaged with the
corresponding first and second bevel gears (12) (51) and the slidable
spline device (61) is disengaged. Therefore, rotational force transferred
from an electric motor (not shown), through the first, third, fourth
and second bevel gears (12) (6) (7) (51), can be used to drive the
main shaft (5) in rotation.
The coupling of the upper and lower curved rings (41) (42) of the
curved coupling (4) are used to prevent relative rotation between
the lower rotatable housing (2) and the upper seat (3), so that
the desired angular position of the lower rotatable housing (2)
can be accurately achieved. The hydraulic cylinder (81) in association
with the piston (82), under the operation of a hydraulic system,
may maintain the lower rotatable housing (2) in the first position.
However, if the hydraulic system malfunctions, the steel ball (833)
biased by the compressed spring (832) in association with the annular
groove (841) of the annular supporting ring (84) may also effectively
maintain the lower rotatable housing (2) in the first position,
so as to ensure the safety and security of operation.
Referring to FIG. 6 when the pressure of the hydraulic oil in
the hydraulic cylinder (81) pushes the piston (82) outwardly to
abut against the upper gland ring (83), the lower rotatable housing
(2) moves in the axial direction of the bevel gear axle (21) to
the second position where the lower rotatable housing (2) is closest
to the upper seat (3). At the second position, the upper and lower
curved rings (41) (42) of the curved coupling (4) are disengaged.
When the lower rotatable housing (2) moves outwardly, the third
bevel gear (6) biased by the compressed spring (71) moves away from
the fourth bevel gear (7) and remains engaged with the first bevel
gear (12). The axially sliding movement of the third bevel gear,
(6) caused by the biased spring (71), moves the slidable spline
device (61) to an engaged condition, so that the bevel gear axle
(21) can be rotated with the third bevel gear (6). At this time,
since the curved coupling is uncoupled and the bevel gear axle (21)
fixed in the lower rotatable housing (2) engages the third bevel
gear (6) through the slidable spline device (61), the rotational
force transferred from the main transmission shaft (11), through
the first and third bevel gears (12) (6), may slowly and smoothly
rotate the lower rotatable housing (2) to a desired angular position.
When a strategically positioned sensor (not shown) detects that
the lower rotatable housing (2) has reached the required angular
position (such as the horizontal position shown in FIG. 7), the
main transmission shaft (11) ceases rotation. Through the piston
(82) and supporting bolts (86), the hydraulic cylinder (81), under
operation of hydraulic pressure, pulls the lower rotatable housing
(2) back to the first position, so that the upper and lower curved
rings (41) (42) of the curved coupling (4) are engaged. And, the
third bevel gear (6) is pushed by the first bevel gear (12) and
moves toward the fourth bevel gear (7), so that the slidable spline
device (61) returns to the disengagement condition. Therefore, rotational
force may be transferred through the main transmission shaft (11),
the first, third, fourth and fourth bevel gears (12) (6) (7) (51)
to drive the main shaft (5) in rotation.
The present invention achieves the objective of changing the required
vertical/horizontal position through the transmission of rotational
force from said main transmission shaft without using any additional
driving apparatus. The result is simplicity in structure that solves
the problem with limited space available within a machine tool so
as to construct a driving apparatus, which is both dependable and
inexpensive.
In addition, during the changing of the vertical/horizontal positions
of the main shaft (5), all the bevel gears remain in contact with
one another through the use of compressed springs (71) and therefore
avoid the problems of wear and tear of the gears and clearance between
the gears. Since there are no relative movements among the components,
smooth operations are achieved. In addition, if the hydraulic system
malfunctions, ball (833) biased by the compressed spring (832) in
association with the annular groove (841) of the annular supporting
ring (84) is also sufficient to effectively maintain the lower rotatable
housing (2) in the first position, so as to ensure safety and security
of operation. |