Machine tools abstract
A work positioning jig for machine tools is attached to a table
with use of a T-slot formed in a work holding surface of the table
to position work in place. The jig comprises a jig body having a
positioning portion to be brought into contact with the work, and
a wedgelike pressing portion formed integrally with and projecting
downward from the lower end of the positioning portion centrally
thereof. A vertical pin extends through the positioning portion
and the pressing portion of the jig body centrally thereof and is
movable upward and downward. The pin has attached to its lower end
a U-shaped brace member fitted over the pressing portion from below
and to be fitted into the T-slot of the table. The pin is biased
upward by the force of coned disk springs, with the brace member
inserted in the T-slot, thereby causing the pressing portion to
expand upright walls of the brace member into pressing contact with
side faces of the table defining the T-slot. The jig can be attached
to the table easily.
Machine tools claims
What is claimed is:
1. A work positioning jig for machine tools which is to be attached
to a work fixing member of the machine tool with use of a recessed
portion formed in a work holding surface of the fixing member to
position work in place, the work positioning jig being characterized
in that the jig comprises a jig body having a positioning portion
to be brought into contact with the work and a tapered pressing
portion fixedly provided at one end of the positioning portion and
to be inserted into the recessed portion, a pin extending through
the jig body and movable relative to the jig body longitudinally
thereof, a brace member attached to the pin at an end portion thereof
projecting beyond the pressing portion so as to fit over the pressing
portion, movable relative to the jig body and to be fitted into
the recessed portion, and means for biasing the pin in a direction
opposite to the pressing portion with respect to the jig body, the
pin being biased by the biasing means to bring one end of the positioning
portion of the jig body adjacent to the pressing portion into face-to-face
contact with the work holding surface while causing the pressing
portion to expand the brace member into pressing contact with faces
of the recessed portion perpendicular to the work holding surface.
2. A work positioning jig for machine tools according to claim
1 which is characterized in that the recessed portion formed in
the work holding surface is a slot, the pressing portion being in
the form of a tapered wedge, the brace member being approximately
U-shaped and having inner surfaces so inclined as to be positioned
away from each other toward the
positioning portion, the pin being biased by the biasing means
to cause the pressing portion to expand opposed walls of the brace
member into pressing contact with respective opposite side faces
of the fixing member defining the slot.
3. A work positioning jig for machine tools according to claim
1 which is characterized in that the recessed portion formed in
the work holding surface is a cylindrical bore, the pressing portion
being in the form of a cone having an outer peripheral surface decreasing
in diameter toward a direction away from the positioning portion,
the brace member being in the form of a hollow cylinder increasing
in inside diameter toward the positioning portion, the brace member
having a plurality of slits formed in a peripheral wall thereof
and arranged at a spacing circumferentially thereof, the pin being
biased by the biasing means to cause the pressing portion to expand
the peripheral wall of the brace member into pressing contact with
an inner periphery of the fixing member defining the cylindrical
bore.
Machine tools description
BACKGROUND OF THE INVENTION
The present invention relates to work positioning jigs to be attached
to work fixing members of machine tools using recesses formed in
the work holding surface of the fixing member.
Conventionally work is fastened to the work holding surface of
a table (work fixing member) of a machine tool, for example, by
an arrangement as shown in FIG. 5. With reference to FIG. 5 the
work holding surface 1a of a table 1 is formed with a plurality
of parallel T-slots 2 (recessed portions) each left open at lengthwise
opposite ends thereof. A plurality of work positioning jigs 3 are
attached to the table 1 using some of the T-slots 2. The position
of the work W is determined by the jigs 3 with respect to an X-direction
(see the arrow X) and a Y-direction (see the arrow Y). A plurality
of clamps 4 are also attached to the table 1 using some T-slots
2. The work W is fixed to the table 1 by the clamps 4.
FIG. 6 shows the work positioning jig 3 heretofore used as attached
to the table 1 with use of the T-slot 2. The jig 3 comprises a jig
body 5 having a positioning portion 5a in the form of a bottomed
cylinder and a fitting portion 5b formed at the lower end of the
positioning portion 5a integrally therewith and fittable in a narrow
portion 2a of the T-slot 2 T-slot nut 6 fittable in the T-slot
2 and a bolt 7 extending through the positioning portion 5a and
the fitting portion 5b of the jig body 5 from above and screwed
in the nut 6.
However, to attach the work positioning jig 3 to the table 1 it
is necessary to insert the nut 6 into the T-slot 2 through the opening
at lengthwise one end thereof and to tighten up the bolt 7 as by
a wrench. The jig 3 therefore has the problem of necessitating a
cumbersome procedure. The jig 3 also has the problem of being cumbersome
to remove from the table 1 because it is necessary for removal to
loosen the bolt 7 as by the wrench and to take out the nut 6 from
the lengthwise end opening of the T-slot 2. Further depending on
the type of the work W to be handled, it becomes necessary to use
another work positioning jig 3A (indicated in chain lines in FIG.
5) after such jigs 3 and clamps 4 have been attached to the table
1. In this case, there arises a need to remove the jig 3 already
attached, thereafter install the additional jig 3A and attach the
removed jig 3 again. Every time the jig 3 is thus removed or attached,
the T-slot nut 6 needs to be inserted into or removed from the T-slot
2 through the lengthwise end opening, and the bolt 7 must be loosened
or tightened up, so that the procedure required becomes cumbersome
all the more. Moreover, when the bolt 7 of the additional jig 3A
or of the jig 3 temporarily removed is to be tightened up as by
the wrench, the jig 3 or 3A or the clamp 4 previously installed
is likely to become an obstacle, hence the problem of low work efficiency.
Work W of particular type may require use of an additional jig 3A
after attaching jigs 3 and clamps 4 to the table 1 and temporarily
holding the work W to the table 1. In this case, the jig 3 or clamp
4 previously attached or the work W will interfere with the wrench
or the like for use in tightening up the bolt 7 of the additional
jig 3A to entail the problem of an impaired work efficiency.
Alternatively, the table 1 of the machine tool has a work holding
surface 1a, to which work W is fastened in the manner shown in FIG.
7. Incidentally throughout FIGS. 5 to 8 like parts are designated
by like reference numerals and will not be described repeatedly.
With reference to FIG. 7 the work holding surface 1a of the table
1 is formed with a plurality of cylindrical bores 10 (recessed portions),
and a plurality of work positioning jigs 11 are attached to the
table 1 using some of the cylindrical bores 10. The position of
the work W is determined by the jigs 11 with respect to an X-direction
(see the arrow X) and a Y-direction (see the arrow Y).
FIG. 8 shows the work positioning jig 11 to be attached to the
table 1 using the cylindrical bore 10. The jig 11 comprises a jig
body 12 in the form of a cylinder having a bottom wall 12a, and
a bolt 13 inserted through the bottom wall 12a from above and screwed
in an internally threaded bush 14 which is fixed in the cylindrical
bore 10 by a press fit.
However, the jig 11 has the problem of being cumbersome to attach
to the table 1 since the bush 14 needs to be fixed into the cylindrical
bore 10 by a press fit. The bolt 13 must be tightened up as by a
wrench, hence the problem of necessitating a cumbersome procedure.
Further depending on the type of the work W to be handled, it becomes
necessary to use another work positioning jig 11A (indicated in
chain lines in FIG. 7) after such jigs 11 and clamps 4 have been
attached to the table 1. When the bolt 13 of the additional jig
11A is to be tightened up as by the wrench, the jig 11 or the clamp
4 previously installed is likely to become an obstacle, hence the
problem of low work efficiency. Work W of particular type may require
use of an additional jig 11A after attaching jigs 11 and clamps
4 to the table 1 and temporarily holding the work W to the table
1. In this case, the jig 11 or clamp 4 previously attached or the
work W will interfere with the wrench or the like for use in tightening
up the bolt 13 of the additional jig 11A to entail the problem of
an impaired work efficiency.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a work positioning
jig for use in machine tools which is free of the foregoing problems
and which can be attached to a work fixing member easily.
The present invention provides a work positioning jig for machine
tools which is to be attached to a work fixing member of the machine
tool with use of a recessed portion formed in a work holding surface
of the fixing member to position work in place. The work positioning
jig is characterized in that the jig comprises a jig body having
a positioning portion to be brought into contact with the work and
a tapered pressing portion fixedly provided at one end of the positioning
portion and to be inserted into the recessed portion, a pin extending
through the jig body and movable relative to the jig body longitudinally
thereof, a brace member attached to the pin at an end portion thereof
projecting beyond the pressing portion so as to fit over the pressing
portion, movable relative to the jig body and to be fitted into
the recessed portion, and means for biasing the pin in a direction
opposite to the pressing portion with respect to the jig body, the
pin being biased by the biasing means to bring one end of the positioning
portion of the jig body adjacent to the pressing portion into face-to-face
contact with the work holding surface while causing the pressing
portion to expand the brace member into pressing contact with faces
of the recessed portion perpendicular to the work holding surface.
The work positioning jig of the present invention is attached to
the work fixing member in the following manner. The brace member
is fitted into the recessed portion after the pin and the brace
member have been moved toward a direction opposite to the biasing
direction of the force of the biasing means, i.e., toward the positioning
portion of the jig body, and the force exerted on the pin and the
brace member and acting against the force of the biasing means is
thereafter removed, whereupon the end of the positioning portion
of the jig adjacent to the pressing portion is brought into face-to-face
contact with the work holding surface by the force of the biasing
means. The force also causes the pressing portion to expand the
brace member, pressing this member against the faces of the recessed
portion perpendicular to the work holding surface, whereby the jig
is attached to the work fixing member. The jig of the invention
is removed from the work fixing member in the following manner.
The pin and the brace member are moved in a direction opposite to
the biasing direction of the biasing means against the force of
the biasing means. This releases the brace member from pressing
contact with the above-mentioned faces of the recessed portion,
so that the jig is removed from the work fixing member by withdrawing
the brace member from the recessed portion.
With the conventional jig to be attached to a table (work fixing
member) formed with T-slots, the T-slot nut needs to be inserted
into and removed from the T-slot through a lengthwise end opening
of the slot, whereas the jig of the invention does not require such
a procedure, nor is it necessary to tighten up or loosen a bolt
as by a wrench. The present jig can therefore be attached to the
work fixing member easily. When there arises a need to use an additional
work positioning jig after some jigs and clamps have been attached
to the table, it is not necessary to insert or remove a T-slot nut
into a T-slot through a lengthwise end opening thereof, nor is it
necessary to tighten up or loosen a bolt every time the jig is to
be attached or removed, hence an improved work efficiency. Moreover,
the previously attached jig is unlikely to interfere with the procedure
for attaching the additional jig. This also leads to an improvement
in work efficiency. Further in the case where an additional
jig is to be used after the work has been temporarily held in place,
the jig or clamp previously attached or the work will not become
an obstacle to ensure an improved work efficiency.
Whereas the conventional jig to be attached to a table formed with
cylindrical bores requires the procedure of fixing an internally
threaded bush into the bore by a press fit, the work positioning
jig of the invention for use in machine tools does not require such
a procedure. Moreover, there is no need to use a wrench or the like
for tightening up or loosening. Thus, the jig can be attached to
the work fixing member by a facilitated procedure. Every time the
jig is to be removed and attached for the use of an additional positioning
jig after some jigs and clamps have been installed on the table,
no bolt needs to be tightened up or loosened, hence an improved
work efficiency. Moreover, the jig previously attached is unlikely
to become an obstacle in installing the additional jig. This ensures
an improved work efficiency. Even when an additional jig is to be
used after work has been temporarily held in place, there is no
likelihood that the previously attached jig or clamp or the work
will interfere with the handling of the additional jig, hence an
improvement in work efficiency.
With the work positioning jig of the invention for use in machine
tools, the recessed portion formed in the work holding surface is
a slot, the pressing portion being in the form of a tapered wedge,
the brace member being approximately U-shaped and having inner surfaces
so inclined as to be positioned away from each other toward the
positioning portion, the pin being biased by the biasing means to
cause the pressing portion to expand opposed walls of the brace
member into pressing contact with respective opposite side faces
of the fixing member defining the slot.
In attaching the jig to the work fixing member in this case, the
force of the biasing means moves the brace member with the pin toward
the pressing portion, which in turn expands the opposed walls of
the brace member into pressing contact with the respective side
faces defining the slot. Since the brace member is pressed against
the slot-defining side faces by the force of the biasing means while
moving toward the positioning portion of the jig body, the positioning
portion is pressed against the work holding surface by the reaction
of the biasing force, with the result that the jig can be fastened
to the fixing member more firmly. On the other hand, when the pin
is moved in a direction opposite to the biasing direction against
the force of the biasing means to remove the jig from the work fixing
member, the brace member moves toward the outer end of the pressing
portion relative thereto, whereby the opposed walls of the brace
member are released from the pressing contact with the slot-defining
side faces.
Alternatively with the work positioning jig of the invention for
use in machine tools, the recessed portion formed in the work holding
surface is a cylindrical bore, the pressing portion being in the
form of a cone having an outer peripheral surface decreasing in
diameter toward a direction away from the positioning portion, the
brace member being in the form of a hollow cylinder increasing in
inside diameter toward the positioning portion, the brace member
having a plurality of slits formed in a peripheral wall thereof
and arranged at a spacing circumferentially thereof, the pin being
biased by the biasing means to cause the pressing portion to expand
the peripheral wall of the brace member into pressing contact with
an inner periphery of the fixing member defining the cylindrical
bore.
In attaching the jig to the work fixing member in this case, the
force of the biasing means moves the brace member with the pin toward
the pressing portion, which in turn expands the peripheral wall
of the brace member into pressing contact with the inner periphery
of the fixing member defining the cylindrical bore. Since the brace
member is pressed against the bore-defining inner periphery by the
force of the biasing means while moving toward the positioning portion
of the jig body, the positioning portion is pressed against the
work holding surface by the reaction of the biasing force, with
the result that the jig can be fastened to the fixing member more
firmly. On the other hand, when the pin is moved in a direction
opposite to the biasing direction against the force of the biasing
means to remove the jig from the work fixing member, the brace member
moves toward the outer end of the pressing portion relative thereto,
whereby the peripheral wall of the brace member is released from
the pressing contact with the bore-defining inner periphery.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective view showng a first embodiment
of work positioning jig of the invention;
FIG. 2 is a view in vertical section showing the jig as attached
to a table having T-slots;
FIG. 3 is an exploded perspective view showing a second embodiment
of work positioning jig of the invention;
FIG. 4 is a view in vertical section showing the jig of the second
embodiment as attached to a table having cylindrical bores;
FIG. 5 is a perspective view showing a conventional method of attaching
work to the table of a machine tool;
FIG. 6 is an enlarged fragmentary view in vertical section showing
a work positioning jig as attached to the table by the method of
FIG. 5;
FIG. 7 is a perspective view showing another conventional method
of attaching work to the table of a machine tool; and
FIG. 8 is an enlarged fragmentary view in vertical section showing
a work positioning jig as attached to the table by the method of
FIG. 7.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
FIGS. 1 and 2 show this embodiment, i.e., a work positioning jig
of the invention for use with a table which has a work holding surface
formed with T-slots.
FIG. 1 shows the work positioning jig, and FIG. 2 shows the jig
as attached to the table of a machine tool.
With reference to FIGS. 1 and 2 the work positioning jig 20 comprises
a jig body 21 having a positioning portion 31 in the form of a solid
cylinder and having a peripheral surface to be brought into contact
with work W for positioning the work W in place and a wedgelike
pressing portion 32 formed integrally with the positioning portion
31 and projecting downward from the lower end of the portion 31
centrally thereof, a vertical pin 22 extending through the positioning
portion 31 and the pressing portion 32 of the jig body 21 centrally
thereof and movable upward and downward, a U-shaped brace member
23 attached to the lower end portion of the vertical pin 22 projecting
downward beyond the pressing portion 32 fitted over the pressing
portion 32 from below and to be fitted into the narrow portion 2a
of a T-slot 2 of a table 1 and a plurality of coned disk springs
24 for biasing the pin 22 upward relative to the jig body 21.
A vertical stepped bore 25 comprising an upper large portion 25a
and a lower small portion 25b extends through the positioning portion
31 and the pressing portion 32 of the jig body 21. The lower small
portion 25b of the bore 25 has an inside diameter approximately
equal to the outside diameter of the pin 22. The pressing portion
32 extending from the lower end of the positioning portion 31 of
the jig body 21 has opposite sides adapted for face-to-face contact
with opposite side portions of the table 1 which define the T-slot
2 formed in the work holding surface 1a thereof. The pressing portion
32 of the jig body 21 expands the brace member 23 under the action
of the disk springs 24 pressing the brace member 23 against opposite
side faces of the table 1 which define the narrow portion 2a of
the T-slot 2 in the table and which are perpendicular to the work
holding surface 1a. The side surfaces of the pressing portion 32
are so inclined as to approach each other as they extend downward.
The inclined surfaces are indicated at 32a.
The vertical pin 22 is inserted through the stepped bore 21 from
above the jig body 21 and has its lower portion slidably inserted
in the lower small bore portion 25b and is thereby prevented from
wobbling. The vertical pin 22 is integrally formed, at an upper
portion thereof positioned within the upper large bore portion 25a,
with a spring retainer 22a in the form of an outer flange and having
an outside diameter not greater than the inside diameter of the
large bore portion 25a. The portion of the vertical pin 22 upward
from the spring retainer 22a vertically movably extends through
a closure 27 which is removably attached to the upper end of the
positioning portion 31 of the jig body 21 for closing the upper-end
opening of the stepped bore 25.
The coned disk springs 24 are fitted around the vertical pin 22
between a stepped portion 25c of the bore 25 and the spring retainer
22a of the pin 22 biasing the pin 22 upward relative to the jig
body 21 at all times.
The brace member 23 comprises a horizontal wall 23a and a pair
of upright walls 23b opposed to each other and integral with the
horizontal wall 23a, and is fastened by a nut 28 to an externally
threaded lower end portion 22b of the pin 22 which portion has a
reduced diameter. More specifically, the externally threaded portion
22b is inserted through a bore 29 vertically extending through the
horizontal wall 23a of the brace member 23 and the nut 28 is screwed
on the lower end of the threaded portion 22b, whereby the brace
member 23 is fixed to the pin 22. The upright walls 23b of the brace
member 23 each have a vertical outer surface, and the distance between
the vertical outer surfaces is not greater than the width of the
narrow portion 2a of the T-slot 2. The upright walls 23b have on
inner sides thereof respective inclined surfaces 30 slanting in
directions away from each other as the walls extend upward. When
the brace member 23 moves upward relative to the pressing portion
32 of the jig body 21 the inclined surfaces 30 32a act to expand
the two upright walls 23b of the brace member 23 outward, pressing
the walls 23b against opposite side faces of the table 1 which define
the narrow portion 2a of the T-slot 2 in the table and which are
perpendicular to the work holding surface 1a.
To attach the work positioning jig 20 thus constructed to the table
1 of the machine tool using the T-slot 2 the brace member 23 is
fitted into the narrow portion 2a of the T-slot 2 first, with the
pin 22 moved down against the biasing force of the coned disk springs
24 to bring opposite side portions of the pressing portion 32 of
the jig body 21 at the lower end of its positioning portion 31 into
face-to-face contact with the side portions defining the T-slot
2 in the work holding surface 1a. When the pin 22 is subsequently
returned, the pin 22 and the brace member 23 are urged upward by
the force of the springs 24 permitting the pressing portion 32
to act as a wedge to expand the two upright walls 23b of the brace
member 23 outward and press the walls 23b against the respective
side faces defining the narrow portion 2a of the T-slot 2. In this
way, the jig 20 is fixed to the table 1 (see FIG. 2).
The jig 20 is removed from the table 1 by moving the pin 22 down
against the biasing force of the disk springs 24 to thereby lower
the brace member 23 relative to the pressing portion 32 and release
the two upright walls 23b from pressing contact with opposite side
faces defining the T-slot 2 and thereafter withdrawing the brace
member 23 from the T-slot 2 upward.
Second Embodiment
FIGS. 3 and 4 show this embodiment, i.e., a work positioning jig
of the invention for use with a table which has a work holding surface
formed with cylindrical bores.
FIG. 3 shows the work positioning jig, and FIG. 4 shows the jig
as attached to the table of a machine tool.
In the case of this embodiment, the body 21 of the work positioning
jig 35 has a conical pressing portion 36 having an outer peripheral
surface which decreases in diameter downward. A brace member 37
is in the form of a cylinder having an open upper end and a bottom
wall 37a and increases in inside diameter upward. A vertical pin
22 has an externally threaded portion 22b inserted through a vertical
through bore 38 formed in the bottom wall 37a of the brace member
37. A nut 28 is screwed on the lower end of the threaded portion
22b, whereby the brace member 37 is fixed to the pin 22. The peripheral
wall 37b of the brace member 37 is formed with a plurality of slits
39 arranged at a spacing circumferentially thereof and extending
downward from the upper end of the wall. Further formed between
each pair of adjacent slits 39 of the brace member 37 is a slit
40 formed in the bottom wall 37a, extending from the inner periphery
of the wall 37a radially outward to the peripheral wall 37b and
further extending in the wall 37a upward. With the exception of
the above feature, the second embodiment is the same as the first,
and like parts are designated by like reference numerals and will
not be described repeatedly.
To attach the work positioning jig 35 thus constructed to the table
1 of the machine tool using the cylindrical bore 10 the brace member
37 is fitted into the cylindrical bore 10 first, with the pin 22
moved down against the biasing force of the coned disk springs 24
to bring the periphery of the pressing portion 36 of the jig body
21 at the lower end of its positioning portion 31 into face-to-face
contact with the table inner periphery 10a defining the cylindrical
bore 10 in the work holding surface 1a. When the pin 22 is subsequently
returned, the pin 22 and the brace member 37 are urged upward by
the force of the springs 24 permitting the pressing portion 36
to act as a wedge to expand the peripheral wall 37b of the brace
member 37 outward and press the wall 37b against the bore-defining
inner periphery 10a. In this way, the jig 35 is fixed to the table
1 (see FIG. 4).
The jig 35 is removed from the table 1 by moving the pin 22 down
against the biasing force of the disk springs 24 to thereby lower
the brace member 37 relative to the pressing portion 36 and release
the peripheral wall 37b from pressing contact with the inner periphery
10a defining the cylindrical bore 10 and thereafter withdrawing
the brace member 37 from the cylindrical bore 10 upward.
According to the foregoing two embodiments, the pressing portion
of the jig body is integral with the positioning portion thereof,
whereas this is not limitative; the pressing member may be provided
by fixing a separate member to the positioning portion. Although
the table for use with the foregoing two embodiment is horizontal,
the jig of the present invention is usable also for an inclined
or vertical table. Further although the work fixing member of the
machine tool is a table in the case of the foregoing two embodiments,
the fixing member is not limited to the table but can be other member. |