Method and apparatus for feeding rod-like workpieces to a severing machine

A method and apparatus for periodically feeding a rod-like workpiece into a severing machine for severing predetermined lengths in a cutting plane during cutting steps alternating with feeding steps. There are provided openable and closable clamping jaws for grasping the workpiece adjacent the cutting plane during each cutting step and openable and closable feed jaws for grasping the workpiece at a predetermined distance upstream of the cutting plane as viewed in the direction of feed and advancing the workpiece through the cutting plane by a distance corresponding to the desired length to be cut. The feed jaws are, subsequent to the feeding step and the closing of the clamping jaws, but prior to the completion of the cutting step, opened and moved away from the cutting plane by an extent that corresponds to the subsequent feed stroke and are thereafter closed again to grasp the workpiece anew.

BACKGROUND OF THE INVENTION 
This invention relates to a method and an apparatus for feeding rod-like 
material (hereafter "workpiece") to a severing machine, such as a frame 
saw, a circular cold saw, a band saw or the like. The workpiece which is 
supported on a machine table and on a feeding device arranged upstream of 
the machine table as viewed in the direction of feed, is, during the 
severing operation, clamped in the zone of the cutting plane between at 
least two jaws which may be opened and closed in a direction transverse to 
the direction of feed. Between two cutting steps the workpiece is advanced 
(fed) to the severing machine by means of at least two feed jaws (forming 
part of the feeding device) which can be opened and closed in a direction 
transverse to the direction of feed. This cyclical feeding operation which 
is usually automatically controlled by a preset control device, involves 
the difficulty in maintaining the final length portion of the workpiece 
(after the consecutive severing steps) as short as possible in an effort 
to reduce waste. 
According to the prior art devices the clamping shoes are divided or have a 
notch in the zone of the cutting plane of the saw blade so that they grasp 
the workpiece at both sides of the cutting plane. The workpiece feed is 
effected by opening the feed jaws subsequent to a cutting step in order to 
execute a return motion of the feed jaws to an extent which equals the 
length of the next feed, while the leading end of the rod is maintained 
clamped by that part of the clamping jaws which are situated at the feed 
side (that is, at the upstream side) of the cutting plane. Then the feed 
jaws again grasp the workpiece and in an open position of the clamping 
jaws, advance the workpiece to the desired extent. Thereafter, the 
clamping jaws are closed and the consecutive cutting operation is started. 
In this arrangement the minimum remaining workpiece length is determined 
by that portion of the clamping jaws which lie at the upstream side of the 
cutting plane as well as a minimum length which is just sufficient to be 
still securely grasped by the feed jaws. 
In order to reduce the residual length (waste length) of the workpiece, it 
has been known to provide the feed-side part of the clamping jaws with a 
recess into which the feed jaws may telescope to arrive closer to the 
cutting plane. Even in such an arrangement, the waste length of the 
workpiece is substantial and may be many times greater than the programmed 
length to be severed, so that waste lengths are obtained from which at 
least one more programmed length portion could have been severed. 
SUMMARY OF THE INVENTION 
It is an object of the invention to provide an improved method and 
apparatus for reducing the waste length of rod-like workpieces to the 
minimum necessary to ensure that the workpiece is still securely grasped 
by the feed jaws. It is a further object of the invention to modify known 
means without additional expense. 
These objects and others to become apparent as the specification 
progresses, are accomplished by the invention, according to which, briefly 
stated, the feed jaws are, subsequent to the feeding step and the closing 
of the clamping jaws, but prior to the completion of the cutting step, 
opened and moved away from the cutting plane by an extent that corresponds 
to the subsequent feed stroke and are thereafter closed again to grasp the 
workpiece anew. 
The above-outlined operational cycle of the feed jaws according to the 
invention thus ensures that the workpiece is already grasped by the feed 
jaws and is thus ready for the feeding operation before the cutting 
operation is terminated. It is thus no longer necessary to hold the 
leading end of the workpiece by the clamping jaws after execution of the 
cutting step while the feed jaws are executing their return motion and 
again grasp the workpiece. 
According to a further advantageous feature of the method according to the 
invention, the feed jaws are opened prior to the beginning of the cutting 
step, then are moved away from the cutting plane by an extent that 
corresponds to the subsequent workpiece feed and then closed again. In 
this way it is ensured that during the cutting operation the workpiece is 
also held firmly at a location which is at a substantial distance from the 
cutting plane so that oscillations and/or tilting forces can have no 
effect. 
According to a further feature of the inventive method, the workpiece end 
which is upstream of the cutting plane (as viewed in the direction of 
feed) is supported against the cutting force during the cutting operation 
on the side which extends in the direction of the cutting force which, in 
turn, is generally parallel to the machine table. This measure is 
particularly advantageous when very long length portions are being cut 
from the workpiece and consequently, the feed jaws have a significant 
distance from the clamping jaws during the cutting operation. Under such 
circumstances, towards the end of the cutting step, dependent upon the 
cutting forces, on the remaining terminal portion of the workpiece a 
transverse force may be exerted which cannot be fully counteracted by the 
feed jaws, so that in the absence of the above-noted additional support, 
the workpiece could get out of alignment. 
As a result of the method according to the invention, the apparatus for 
performing the method can be so structured that the clamping jaws, as 
viewed in the direction of feed, are located exclusively downstream of the 
cutting plane and further, the feed jaws can be advanced up to the 
immediate vicinity of the cutting plane. 
By virtue of the fact that the workpiece is grasped by the feed jaws as 
early as prior to the completion of the cutting step, it is no longer 
required--as noted above--that the leading end of the workpiece be still 
held by the clamping jaws after the cutting operation, so that the part of 
the clamping jaws which heretofore has been arranged at the upstream side 
of the cutting plane can be dispensed with. This, in turn, permits to 
advance the feed jaws during feed immediately up to the cutting plane, so 
that after the last cut from each workpiece there remains only such a 
minimal length (waste length) which is needed for being securely grasped 
by the feed jaws. 
For the above-discussed support of the workpiece end at its side lying in 
the effective direction of the cutting force, there is provided a pivotal 
pawl which, in its operative position, is in alignment with that clamping 
jaw face which is situated on the same side of the workpiece. The pawl may 
be pivoted in the feeding direction away from the cross-sectional zone of 
the workpiece against a spring force. The pawl is shiftable as a unit with 
the clamping jaw which is displaceable transversely to the direction of 
feed. The pawl supports the rod-like workpiece particularly towards the 
end of the cutting step; during the feeding motions of the feed jaws, 
however, the pawl can be pivoted by one of the feed jaws out of the way 
from the cross-sectional zone of the workpiece.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Turning now to FIG. 1, there is shown a conventional severing machine, more 
particularly, a frame saw which has a machine stand 1, a saw frame 2 and a 
saw blade 3 held taut therein. The machine stand 1 comprises a machine 
table 4 on which a rod-like workpiece (not shown in FIG. 1) to be severed 
is clamped by means of clamping jaws 5 and 6. In the illustrated example, 
the clamping jaw 5 is stationarily mounted, while the clamping jaw 6 can 
be opened and closed by means of a power cylinder assembly 7. 
Turning now to FIG. 2 which illustrates the frame saw of FIG. 1 in top plan 
view, a conventional workpiece feeding device generally designated at 8 is 
arranged upstream of the frame saw, as viewed in the direction of 
workpiece feed. The feeding device 8 essentially comprises a stand 9 on 
which there are mounted rotatable rolls 10 for supporting the workpieces 
and a pair of feed jaws 11 and 12. Of the two feed jaws 11 and 12, the 
feed jaw 12 may be displaced transversely to the feed direction by a power 
cylinder assembly 13 for closing and opening the feed jaw pair. Between 
the feed jaws 11 and 12 there is provided a backup support 14 for the 
workpieces. The feed jaws 11, 12 are, together with the backup support 14, 
displaceable as a unit on the stand 9 for example, by means of a spindle 
drive actuated by a motor 15, towards and away from the frame saw. Thus, 
the feed jaws 11, 12 are displaceable parallel to the arrow I in the plane 
of the drawing FIG. 2. 
As it may be further observed in FIG. 2, the clamping jaws 5 and 6 have 
respective clamp jaw parts 16 and 17 which are situated at the feed side 
(upstream side) of the cutting plane defined by the saw blade 3. The 
clamping jaw parts 16 and 17 which characterize prior-art arrangements, 
have the function to firmly hold the leading end of the rod-like workpiece 
while, after the completion of a cutting step, the feed jaws 11 and 12 are 
opened and are shifted away from the saw and then are again closed in 
order to feed the consecutive length portion of the workpiece in the 
direction of the saw. The clamping jaw parts 16 and 17, however, affect 
the size of the waste length of the workpiece (which can no longer be 
further severed), inasmuch as the waste length has to be, in addition to 
the minimum length required for the feed jaws 11 and 12 to securely grasp 
the workpiece, longer by an amount corresponding to the width of the 
clamping jaw part 16 and 17 as measured in the direction of feed. 
Turning now to FIG. 3, there is illustrated the severing machine and the 
feeding device 8a according to the invention. In FIG. 3 components that 
are identical to those shown in FIG. 2 are designated with the same 
reference numerals, but are not referred to again in the description 
except if they are of significance regarding structural and/or operational 
features of the invention. 
In FIG. 3, the cutting plane 20 defined by the saw blade 3 is designated in 
broken lines in the zone of the saw frame 2. As seen in FIG. 3, the 
clamping jaws 21 and 22 are situated only on the downstream-side of the 
cutting plane 20 (as viewed in the direction of feed). Thus, as opposed to 
the prior art shown in FIG. 2, the clamping jaws do not have any parts 
that extend beyond the cutting plane 20 into the upstream side thereof, 
that is, into that side where the feeding device 8a is located. This 
condition permits the feed jaws 11 and 12 to be advanced to the immediate 
vicinity of the cutting plane 20 during workpiece feed so that the 
residual workpiece length (waste length) has to be only of such a size 
that the workpiece can still be securely gripped by the feed jaws 11 and 
12 for performing the last cut on the workpiece. 
The feeding device 8a has a limit switch 23 which causes stoppage of the 
feed motion of the feed jaws 11 and 12 at the moment when their leading 
edge arrives at the immediate vicinity of the cutting plane 20 at the 
upstream side thereof. The feeding device 8a further has another limit 
switch 24 which is adjustable and determines the length of the return 
stroke of the feed jaws 11 and 12 to thus determine the length by which 
the workpiece is advanced. This magnitude is settable with the aid of a 
fixed scale 25' along which the limit switch 24 may be shifted. 
The method of feeding the workpieces according to the invention which makes 
possible to dispense with the clamping jaw parts 16 and 17 shown in FIG. 2 
will now be discussed in conjunction with FIG. 4. 
First, the rod-like workpiece 25 is brought into its illustrated position 
by the feed jaws 11, 12 which assume their position immediately adjacent 
the cutting plane 20 as shown in solid lines. During the feed, the 
clamping jaws 21 and 22 were open and now, in the solid-line end position 
of the feed jaws 11, 12 they close. Thereafter, prior to the beginning of 
the severing operation but not later than just prior to the completion 
thereof, the feed jaws 11 and 12 are opened and are displaced into the new 
feed position 11' and 12' (shown in broken lines) and there, again not 
later than prior to the completion of the cutting step, they are closed 
and thus grasp the workpiece. Upon completion of the cutting step, the 
clamping jaws 21, 22 open by virtue of the clamping jaw 22 moving 
transversely to the direction of feed into the phantom-line position 22' 
and thus the consecutive feed may take place with the aid of the feed jaws 
11 and 12. Thereafter, the above-described cycle is repeated. 
As seen in FIG. 4, the residual length (waste length) R can be very short 
and need not be longer than what is necessary to ensure that the last 
workpiece portion--from which a programmed length will still be cut--can 
still be securely grasped by the feed jaws 11 and 12. 
In cases where, during each cycle, large workpiece lengths are to be 
advanced, and thus the feed jaws 11 and 12 have, precisely at the time the 
severing operation is completed, a substantial distance from the cutting 
plane 20, it is advisable to additionally support the workpiece 25 at a 
location close to the clamping jaws 21 and 22 at that side towards which 
the cutting force derived from the operation of the saw blade is directed. 
In case of a substantial distance of the feed jaws 11 and 12 from the 
cutting plane 20, the transverse force which depends from the cutting 
force and which is exerted on the workpiece 25 towards the end of the 
cutting operation, may reach such a magnitude that the feed jaws 11 and 12 
are no longer capable of preventing a misalignment of the workpiece in the 
vicinity of the cutting plane 20. Thus, for effecting the above-noted 
additional support of the workpiece 25, there is provided a pawl 26 which 
is mounted on a component 27 by means of a pin 28 for pivotal motion about 
an axis perpendicular to the plane of the drawing FIG. 4. The component 27 
is integral with the moving member of the power cylinder assembly 7 and 
thus moves in unison with the clamping jaw 22 during the opening and 
closing motions thereof. The pawl 26 is biased by a spring 29 which seeks 
to pivot the pawl 26 into its phantom-line position against a stop 30 
supported on the component 27. In the phantom-line position, the leading 
edge 31 of the pawl 26 is coplanar with the clamping face of the clamping 
jaw 22. 
The pawl 26 pivots, under the effect of the spring 19, automatically into 
the phantom-line position shown in FIG. 4 when the feed jaws 11 and 12 
move back into their position 11' and 12'. When, on the other hand, the 
workpiece 25 is advanced, the pawl 26 is pivoted out of the way by the 
feed jaw 12 into the solid-line position as shown in solid lines in FIG. 
4. 
It is to be noted that the spring 29 is illustrated in FIG. 4 essentially 
in a symbolic manner. In practice, underneath the pawl 26 a 
torque-exerting spring or the like is arranged in order to maintain the 
required structural space at a minimum as it may be better observed in 
FIG. 3. 
It is further to be understood that the disclosed pawl 26 is only a simple 
although expedient example for supporting the workpiece 25. This function 
could be achieved by a backup support operated by a separate power 
cylinder assembly similarly to the clamping jaw 22. Such a backup support 
would be moved, prior to the beginning of the cutting operation and 
subsequent to the return stroke of the feed jaws 11 and 12 into the 
positions 11' and 12', against the workpiece 25 and would then be 
withdrawn prior to the consecutive feed effected by the feed jaws 11 and 
12. 
It will be understood that the above description of the present invention 
is susceptible to various modifications, changes and adaptations, and the 
same are intended to be comprehended within the meaning and range of 
equivalents of the appended claims.