Note: Descriptions are shown in the official language in which they were submitted.
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PUNCHING APPARAZZTS
SPECIFICATION
rlsr.D oa THS INV$NTION
The present invention relates to a punching apparatus.
More particularly this invention concerns an apparatus for the
hot calibrating and punching of holes in a workpiece.
BACKGROUND OF THS INVENTION
In the hot formation of various machine parts, for
instance piston rods, it is frequently necessary to form accu-
rately dimensioned transverse holes in the workpiece. This is
most easily done when the workpiece is still hot, often 1050°C to
1100°C for aluminum, and the most accurate holes are produced
most efficiently by punching.
When the workpiece requires two coaxial holes in
opposite arms or walls that are relatively closely spaced, it is
fairly difficult to create the holes without deforming the
workpiece. The arms must be supported as each of the holes is
driven, typically by an insert that is fitted between the arms.
This insert has an inner hole big enough to receive the punched-
out piece, and the operation must be carried out horizontally,
that is by punching down, to ensure that the punched-out piece
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drops into the insert. When the arms are relatively closely
spaced, the insert cannot be made strong enough to withstand the
force of the punching operation so that the workpiece is detri-
mentally deformed. During such an operation which requires
repositioning the workpiece to punch out the second side, valu-
able time is lost and the workpiece can cool excessively.
Furthermore the arm being punched is not supported around the
edges of the hole where the punch pushes through, often leading
to a ragged formation or push-through.
OHJECTB OF THB INVENTIODT
It is therefore an object of the present invention to
provide an improved apparatus for punching transversely through-
going coaxial holes in spaced walls of a workpiece.
Another object is the provision of such an improved
apparatus for punching transversely throughgoing coaxial holes in
spaced walls of a workpiece which overcomes the above-given
disadvantages, that is which is extremely fast and simple so that
it can be applied readily to a high-volume mass-production
operation.
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BUMMARY OF THE INVENTION
An apparatus for punching transversely throughgoing
coaxial holes in spaced walls of a workpiece has according to the
invention a holder supporting the workpiece and an outer tool
part formed with a pair of transverse bores and displaceable
between an advanced position engaged over the workpiece on the
holder and outwardly flanking the walls and a retracted position
spaced from the workpiece and holder. An inner tool part formed
with a transversely throughgoing bore is displaceable in the
advanced position of the outer tool part between an advanced
position engaged between the walls and with its bore coaxial with
the bores of the outer tool part and a retracted position with
its bore spaced from the workpiece in the holder. The outer tool
part is formed with a waste passage aligned with the inner-part
bore in the retracted position of the inner part. Respective
punches are axially displaceable in the outer-part bores in the
advanced positions of the tool parts to punch a respective piece
from the respective wall and push the punched-out piece into the
bore of the inner tool part. A knockout element can be pushed in
the retracted position of the inner tool part into the inner-part
bore by an actuator to push the piece therein into the waste
passage.
Thus with this system it is merely necessary to advance
the two parts so they fit solidly and complementarily around the
walls of the workpiece. Then at least one of the punches is
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driven through the respective wall to form a hole therein and to
push the punched-out piece into the bore of the inner part. This
inner part is then withdrawn, the piece is knocked out of it into
the waste passage, and if necessary it is again advanced to
repeat the operation with the other wall. The entire cycle can
take place in a few seconds and both walls of the workpiece are
solidly supported throughout. Thus there is no stress to the
workpiece and no time for it to cool off. In fact the complemen-
tart' fit of the parts with the workpiece can serve to true its
shape, and to ensure that the produced bores are perfectly
coaxial.
According to the invention the apparatus has two such
knockout elements flanking the inner part and coaxially displace-
able in the outer part. In addition the outer part is formed
with two such waste passages, one to each side of the inner part.
Respective inner and outer hydraulic actuators con-
nected to the inner and outer tool parts are operable to displace
same between the respective advanced and retracted positions.
Furthermore the means for axially displacing the punches and the
actuator for the knockout element are all hydraulic actuators.
The workpiece is releasably secured to the support and
one or both of the parts has a removable end piece complementa-
rily fittable with the workpiece. Thus when the tool parts are
fitted to the workpiece, it is totally supported and cannot move
at all when being punched, ensuring that the punched hole will be
perfectly accurate.
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BRIEF DESCRIPTION OF THE DRAWINti
The above and other objects, features, and advantages
will become more readily apparent from the following description,
reference being made to the accompanying drawing in which:
FIG. 1 is a section through the apparatus according to
the invention before the start of a punching operation;
FIGS. 2 through 4 are views like FIG. 1 showing suc-
ceeding steps in the punching operation; and
FIG. 5 is section taken along line V--V of FIG. 1.
BPECIFIC DESCRIPTION
As seen in FIGS. 1 and 5 a workpiece 1, here the piston
end of a piston rod, has a pair of arms or walls 1' and is formed
of cast metal, typically steel or aluminum. While still hot it
needs to be formed with a pair of aligned cylindrical bores along
an axis lA which will eventually receive a pin on which a piston
is mounted. This workpiece 1 is mounted on a complementarily
shaped holder 2 with the axis lA normally horizontal.
The hole-punching apparatus comprises an outer tool
part 5 having a core 4 that fits complementarily around the two
walls 1' of the workpiece 1. This outer part 4, 5 can be dis-
placed between the retracted position of FIG. 1 and the advanced
positions of FIGS. 2 through 4 by an outer actuator 8. It is
formed with a pair of coaxial horizontal bores 14 in each of
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which is slidable a punch 6 of the exact cylindrical size and
shape as the holes to be formed in the walls 1' of the workpiece
1. These punches 6 are coaxial on an axis 6A and are each
associated with a heavy-duty hydraulic actuator 13 mounted right
on the outer part 5. In the advanced position the outer part 4,
5 fits snugly over the workpiece 1 with the axis 6A aligned with
the axis lA where holes are to be formed.
In addition the apparatus has an inner tool part 3 that
is displaceable in the outer part 4, 5 and that is formed with a
throughgoing bore 15 of the same size and shape as the bores 14
and in fact alignable in an advanced position shown in FIGS. 1
through 3 with the bores 14. This part 3 fits complementarily
between the walls 1' of the workpiece 1 in the advanced posi-
tions. In a retracted position the bore 15 is aligned with an
axially throughgoing passage 16 which is formed to each side of
the inner part 3 with a waste passage 11 opening outside the
part. An actuator 9 inside the actuator 8 displaces the inner
part 3 relative to~the outer part 4, 5 in the advanced position
of the latter.
The outer part 4, 5 carries a pair of actuators 12 each
carrying a respective knockout pin 7 that are coaxial on an axis
7A parallel to the axis 6A and also constituting the axis of the
passage 16. These knockout pins 7 can be advanced from opposite
sides into the inner-part bore 15 in the retracted position of
same.
The apparatus described above functions as follows:
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To start with as shown in FIG. 1 the workpiece 1 is
fitted to the stationary holder 2 and the parts 3 and 4, 5 are
spaced from it in the retracted positions.
Then as shown in FIG. 2 the outer part 4, 5 and the
inner part 3 are advanced jointly to the advanced positions with
the part 4, 5 fitting snugly around the workpiece 1 and the inner
part 3 fitting snugly between its walls 1'. The cylindrical
bores 14 and 15 are coaxially aligned.
According to FIG. 3 then one or the other of the
actuators 13 advances to punch through the respective wall 1' and
force a piece 10 therefrom into the bore 15. If the space
between the walls 1' were wide enough, it would be possible to
punch out both walls 1' simultaneously but this is not normally
possible.
The inner part 3 is then raised as shown in FIG. 4
until its bore 15 is aligned with the bores 16 and the actuator
12 on the same side as the actuator 13 just operated is operated
to advance the respective knockout pin 7 and push the piece 10
over to the waste passage 11 whence it drops out of the machine.
Two such actuators 12 and punches 7 are needed since the punched-
out piece 10 has one side perpendicular the axis 7A and another
side angled thereto so that if it were pushed by the angled side
it might jam in the bore 15.
The inner part 3 is then lowered and the cycle is
repeated with the punch 6 and pin 7 on the other side of the
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machine to punch a similar hole in the other wall 1' of the
workpiece 1.
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