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BACKGROUND OF THE INVENTION
The present invention relates generally to an apparatus for cutting
successive portions from a column of plastic material such as viscous
glass.
In the glass forming process, glass is fed from an outlet spout of a feeder
bowl to a glass forming machine. A shear mechanism is mounted underneath
the feeder bowl to successively cut gobs from the column of glass from the
feeder bowl. One type of shear mechanism utilizes a pivoted shear
structure wherein shear blades are mounted on swinging arms. In high speed
applications, especially, there is a tendency for excessive wear in
mechanisms of that type. Further, in double or triple gob applications,
the gobs are not cut at exactly the same time. Thus, the gobs will not be
delivered to the molds of a given machine section at exactly the same time
thereby affecting the forming times.
To overcome the above problems, straight line shearing has been proposed.
In straight line shearing, the shear blades advance in a straight line
toward the issuing gobs from opposite directions. U.S. Pat. Nos. 1,642,966
issued to W. J. Miller on Sept. 20, 1927; 3,435,719 issued to F. J. Wythe
on Apr. 1, 1969; and 3,996,037 issued to F. J. Wythe on Dec. 7, 1976 show
examples of straight line shearing. Straight line shearing mechanisms may
also be provided with means to adjust the vertical height of either the
upper or lower shear blades to adjust the "tension" between opposite
blades when they overlap during the cutting stroke. Such an arrangement is
shown in U.S. Pat. No. 3,579,319 issued to F. J. Wythe and H. Hoette on
May 18, 1971. Additionally, the drop guides for guiding the severed gob
during its initial downward movement as it is being separated from the
suspended molten glass column may be adjustable toward and away from the
suspended column of molten glass as also shown in U.S. Pat. No. 3,579,319.
SUMMARY OF THE INVENTION
The present invention has for its object an improved mechanism for straight
line shearing. One feature of the present invention resides in the
provision of mounting means for at least one blade of a set of oppositely
disposed shear blades having relative vertical movement with respect to
the other blade, means for moving said mounting means vertically with
respect to the other blade, and means permitting the one blade to tilt in
the event of excess tension between the two blades.
Another feature of the present invention includes means mounting a drop
guide for movement with an upper shear blade, means for moving said drop
guide in the direction of travel of said shear blade relative to said
shear blade, and means for pivoting said drop guide about a vertical axis.
Yet another feature of the invention is the provision of mounting means for
mounting at least one shear blade of a set of oppositely disposed shear
blades, said mounting means including a blade holder to which said one
blade is attached and having a lower surface, a support member having an
upper surface disposed under said lower surface, pin means positioned
between said upper and lower surfaces and having an axis extending in the
direction of movement of said blade to permit said blade holder to pivot
about said axis relative to said support member, and means for securing
said blade holder to said support member after said blade holder has been
pivoted to the desired position.
Still another feature is the provision of an apparatus for use with a
feeder for shearing gobs from a column of plastic material comprising:
(a) at least one set of oppositely disposed shear blades movable in a
straight line toward and away from each other between open and shearing
positions; and
(b) a pneumatic control system for operating said shear blades, said
control system including:
(i) a source of fluid pressure;
(ii) pneumatic cylinder assembly means including a piston member and
operating rod for driving said shear blades between said open and shearing
positions;
(iii) means connecting said pneumatic cylinder assembly means to said
source of fluid pressure including a first valve having first and second
positions, said first position permitting fluid pressure to flow to one
side of said piston to move said piston into the shearing position, said
second position permitting fluid pressure flow to the other side of said
piston member to move said piston member into the open position;
(iv) means connecting said source of fluid pressure to said first valve to
cause the actuation thereof including a second valve having first and
second positions, said first position permitting fluid pressure to flow to
said first valve to actuate said first valve into its first position, said
second position permitting fluid pressure flow to said first valve to
actuate said first valve into its second position;
(v) means connecting said source of fluid pressure to said second valve to
cause the actuation thereof into its first position and including a third
valve having a normal position blocking fluid pressure flow and an
actuated position permitting fluid pressure flow; and
(vi) means driven by said operating rod to actuate said second valve into
its second position after said shear blades have moved to their shearing
position.
A further feature of the invention is the provision of an apparatus for use
with a feeder for shearing gobs from a column of plastic material
comprising:
(a) at least one set of oppositely disposed shear blades movable in a
straight line toward and away from each other between open and shearing
positions;
(b) pneumatic cylinder assembly means including a piston member and an
operating rod movable by fluid pressure between open and shearing
positions for driving said shear blades between their open and shearing
positions;
(c) means connecting said pneumatic cylinder to a source of fluid pressure
to move said piston member between said open and shearing positions; and
(d) means providing a cushion of fluid pressure for said piston member at
the end of movement of said piston member from its shearing position to
its open position.
A still further feature is the provision of an apparatus for use with a
feeder for shearing gobs from a column of plastic material comprising:
(a) at least one set of oppositely disposed shear blades movable in a
striaght line toward and away from each other between open and shearing
positions;
(b) pneumatic cylinder assembly means including a piston member and an
operating rod movable by fluid pressure between open and shearing
positions for driving said shear blades between their open and shearing
positions;
(c) means connecting said pneumatic fluid to a source of fluid pressure to
move said piston member between its open and shearing positions;
(d) means for controlling the flow of fluid to said piston including normal
return actuating means driven by said operating rod to initiate the return
of said piston member from its shearing position to its open position
after said shear blades have moved to their shearing position; and
(e) automatic return means for effecting return of said piston member to
said open position in the event said shear blades do not travel completely
to the shearing position to enable the normal return actuating means to
initiate the return.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of a shear mechanism incorporating the present
invention;
FIG. 2 is a sectional view taken along the lines 2--2 of FIG. 1;
FIG. 3 is a sectional view taken along the lines 3--3 of FIG. 1;
FIG. 4 is a sectional view taken along the lines 4--4 of FIG. 1;
FIG. 5 is a sectional view taken along the lines 5--5 of FIG. 1;
FIG. 6 is a sectional view taken along the lines 6--6 of FIG. 1;
FIG. 7 is a sectional view taken along the lines 7--7 of FIG. 1;
FIG. 8 is a sectional view taken along the lines 8--8 of FIG. 4;
FIG. 9 is a sectional view taken along the lines 9--9 of FIG. 3;
FIG. 10 is a schematic diagram of a pneumatic control system used to
operate the air cylinder assembly which drives the shear heads of the
mechanism of FIG. 1, the system being shown with the piston of the air
cylinder assembly in the retracted position;
FIG. 11 is a schematic diagram of the pneumatic control system shown as the
piston member of the air cylinder assembly is moving outwardly to drive
the shear heads to their cutting position;
FIG. 12 is a schematic diagram of the pneumatic control system shown just
before the piston member of the air cylinder assembly has reached the end
of its cutting stroke;
FIG. 13 is a schematic diagram of the pneumatic control system shown as the
piston member of the air cylinder assembly is being retracted; and
FIG. 14 is a schematic diagram of the pneumatic control system showing the
operation of the automatic retract feature in the event that the shear
heads are prevented from completing their cutting stroke.
DESCRIPTION OF PREFERRED EMBODIMENT
Referring to the drawings, and in particular, FIG. 1, the shear mechanism
of the present invention includes a frame 2 including spaced end plates 4
and 6 interconnected by a first side rail 8 and upper and lower side rails
10 and 12. The side rails 10 and 12 are parallel to and spaced apart
vertically from each other, and are spaced horizontally from the side rail
8 as shown in FIGS. 5 and 6.
A left-hand or lower shear head 14 is mounted on side rails 8 and 12 of the
frame 2 for horizontal movement relative thereto as shown in FIGS. 1 and
5. A right-hand or upper shear blade 16 is mounted on side rails 8 and 10
of the frame 2 for horizontal movement relative thereto as shown in FIGS.
1 and 6. An air cylinder assembly 18 is also mounted on the frame 2 and
has its operating rod 20 directly connected to the left-hand shear head
14. The operating rod 20 is connected to the right-hand shear blade head
16 through a rack and pinion mechanism 22.
The shear mechanism may be attached to a feeder bowl of a feeder by means
of a mechanism such as shown in U.S. Pat. No. 3,567,418 issued Mar. 2,
1971 to H. Hoette and incorporated herein by reference in its entirety.
For this purpose, a bracket 24 may be attached to the frame 2 for mounting
on the post 26 of the mounting mechanism shown in U.S. Pat. No. 3,567,418.
It is to be understood that the shear mechanism may be attached to the
feeder bowl by other means if desired. As the mounting means and feeder
bowl are not directly involved with the present invention, they have not
been shown in the drawings and will not be described further for the sake
of clarity and simplicity.
With reference to FIGS. 1, 3 and 5, the left-hand or lower shear head 14
includes a carriage member 28 extending between rails 8 and 12. One end of
the carriage member 28 has a C-shaped member 30 attached thereto, with the
member 30 so positioned that the rail 8 is located within the opening 32.
The other end of the carriage member 28 includes an elongated tubular
portion 34 with a circular aperture 36 therethrough. The tubular portion
is mounted on the lower rail 12 with the rail 12, which is circular,
extending through the aperture 36.
A shear blade bracket 38 is attached to the top side of the carriage member
28 by mean of bolts 39 and is provided with two upstanding bosses 40, each
having a square aperture 42 vertically therethrough and its front side,
which faces the right-hand or upper shear head 16, open to form a square
C-shaped configuration. A shear blade holder 44 is mounted within each of
the bosses 40 for sliding movement in a vertical direction with respect to
the shear blade bracket 38. A lower shear blade 46 is attached to the top
horizontal surface 48 of each of the holders 44 by screws 49 or the like.
The forward face of each boss 40 is closed by a spring plate 50 secured to
the bracket 38 by suitable means such as hex screws 52. Positioned within
each boss is a pressure plate 54 which is spaced from the spring plate 50
and is urged against the forward face 56 of the shear blade holder 44 by
means of coil springs 58. A dowel pin 60 extends into openings in the
spring plate 50 and pressure plate 54 to maintain the pressure plate 54 in
proper position. A wear plate 62 is suitably attached to the rear surface
of the shear blade holder 44.
The forward face 56 of each shear blade holder 44 is provided with a slot
64 in which a link member 66 is mounted and pivotally attached to the
holder 44 by means of a pivot pin 68 as shown in FIG. 3. A yoke 70 is
mounted within each boss 40 and has a forward rod portion 72 extending
through an aperture 74 in the spring plate 50 and a rearward rod portion
76 extending through an aperture 78 in the shear blade bracket 38, whereby
the yoke 70 has horizontal relative movement along its axis with respect
to the bracket 38. The lower end of the link member 66 is pivotally
attached to the body 80 of the yoke 70 by means of a pivot pin 82.
A spool member 84 is threadedly received on the rearward rod portion 76 of
each of the yokes 70. Each spool member 84 has a flange 86 at its forward
end which is received within a counterbore 88 in the shear blade bracket
38. A bracket member 90 surrounds each spool member 84 and each is
attached to the shear blade bracket 38 in a suitable manner as by hex
screws (not shown) to captivate the flange of the spool member 84 and
prevent movement thereof relative to the bracket 38 in an axial direction.
A bearing 92 is provided between the bracket member 90 and the spool
member 84 to facilitate rotation of the spool member 84 about its axis
within the bracket member 90.
An indexing head 94 is received on each spool member 84 and is suitably
attached thereto by means such as a roll pin 96. The indexing head 94 is
provided with a circular peripheral surface 98 in which a plurality of
evenly spaced pin members 100 are mounted to extend radially outwardly
from the indexing head 94 as shown in FIG. 9. A spring biased detent 102
is mounted in the bracket member 90 to releasably engage one of a
plurality of slots 104 spaced about the inside face of the indexing head
94 to prevent accidental rotation of the indexing head 94 by vibration or
other causes.
An indexing rod 106 is mounted in a bushing 108 which is attached to the
end plate 4 of the frame 2. Bearings 110 are provided between the bushing
and indexing rod 106 to facilitate rotation of the indexing rod 106. The
indexing rod 106 includes an end portion 112 extending through the end
plate 4 to which is attached a hand knob 114 by suitable means such as a
roll pin 116. The indexing rod 106 extends under the indexing head 94 and
includes an elongated fin 118 mounted in an elongated slot 119 and
projected out of the periphery of the rod portion of the indexing rod 106
a distance sufficient to engage a pin member 100 when the indexing rod is
rotated. The length of the indexing rod 106 and the fin 118 should be
sufficient so that the fin is positioned under the indexing head 94 during
the entire stroke of the shear head 14 so that each blade may be adjusted
while the mechanism is running.
With the arrangement just described, the height of the lower shear blade 46
may be adjusted by turning the hand knob 114. Rotation of the hand knob
114 causes rotation of the indexing head 94 by means of the fin 118
engaging successive pins 100 on the indexing head upon each 360.degree.
rotation of the indexing rod 164. Rotation of the indexing head 94 causes
rotation of the spool member 84 which, in turn, because of its threaded
connection with the yoke 70, causes the yoke 70 to move horizontally along
its axis. Because of the link member 66 provided between the yoke 70 and
shear blade holder 44, horizontal movement of the yoke 70 causes the shear
blade holder to move vertically within the shear blade bracket 38. The
provision of the spring biased pressure plate 54 enables the outer end of
the lower shear blade 46 along with its shear blade holder 44 to tilt for
a purpose to be more fully discussed below.
With reference to FIGS. 1, 4, 6 and 7, the right-hand or upper shear head
16 includes a carriage member 120 mounted on and extending between the
rails 8 and 10 of the frame 2. The carriage member 120 includes at one end
a C-shaped member 122 which rides on the rail 8. The other end of the
carriage member 120 includes an elongated tubular portion 124 surrounding
and riding on the circular rail 12. A shear blade assembly 126 is mounted
on the carriage member 120 and includes an elongated shear blade support
128, two spaced shear blade holders 130 and two upper shear blades 132.
The shear blade support 128 is attached to the carriage member 120 by
suitable screws 134 and includes an upstanding flange 136 running its
entire length at the rearward side. The upper planar surface 138 of the
shear blade support 128 is provided with two spaced semi-circular grooves
140, each being co-axial with one of two circular holes 142 through the
flange 136. A pin member 144 is mounted in each of the grooves 140 and
extends into the associated hole 142 as shown in FIG. 4.
The bottom surface of each shear blade holder 130 is provided with a
semi-circular groove 145 mating with one of the grooves 140 in the shear
blade support 128. The shear blade holder 130 is attached to the shear
blade support 128 by means of two screws 146 positioned on either side of
the axis of the pin member 144. An upper shear blade 132 is attached to
each of the shear blade holders 130 by means of screws 148. When the plane
of the bottom surface of the shear blade holder 130 is parallel to the
plane of the planar upper surface 138 of the shear blade support 128, some
clearance should exist between these faces. With this arrangement, when
screws 146 are loosened, the generally horizontal surface of the shear
blade 132 may be pivoted about the axis of the pin member 144 to adjust
the inclination of the under surface of the upper shear blade 132 so that
it mates correctly with the upper surface of its associated lower shear
blade 46 while shearing.
It will be observed from FIG. 1 that the facing edges of the shear blades
46 and 132 are notched and that they constitute the cutting or shearing
edges of the blade. When the blades are in the cut or shearing position,
the cutting edge of each of the upper blades 132 passes over the cutting
edge of its associated lower blade 46. The gobs having issued from a
feeder (not shown) on the vertical centerline 149 of the orifices, which
centerlines extend through the shear blades 46 and 132 when the blades are
in the cut or shearing position.
As the lower shear blades 46 are each independently adjustable in a
vertical direction, the tension between each set of associated upper and
lower blades may be adjusted. With the arrangement described above, this
adjustment may be made while the blades are moving. Additionally, since
the lower shear blade 46 of each set of blades can tilt in the event of
excess tension, the possibility of damage to the blades and possible
injury due to breakage of the blades is reduced.
A drop guide 150 is mounted for movement with the carriage member 120 under
each of the upper shear blades 132 as shown in FIGS. 1 and 4. Each drop
guide 150 is attached to a drop guide holder 152 by means of a cap screw
154 extending through an aperture 156 in the drop guide 150 which is
provided with a bushing 158 to facilitate pivotal movement of the drop
guide 150 about the axis of cap screw 154 for a purpose to be described
below. The drop guide holder 152 is attached to the carriage member 120 by
virtue of two guide pins 160, attached to the drop guide holder 152 and
sliding received in bushing lined apertures 162 in the carriage member
120. Thus, each drop guide 150 can move in a horizontal direction relative
to the shear blades 132.
An adjusting screw 164 having a head portion 166 at one end received in a
counterbore 168 in the drop guide holder 152 includes a threaded portion
170 received in a threaded bore 172 through the carriage member 120. The
other end of the adjusting screw 164 has an indexing head 174 mounted
thereon and secured against relative movement therewith by a roll pin 176.
As shown in FIGS. 4 and 8, the indexing head 174 is provided with a
circular peripheral surface 178 in which a plurality of evenly spaced pin
members 180 are mounted to extend radially outwardly from the surface 178.
An indexing rod 182 is mounted in a bushing 184 which extends through the
end plate 6 of the frame 2. The indexing rod 182 includes an end portion
186 extending through the outer end of the bushing 184 to which is
attached a sprocket member 188 by suitable means such as a roll pin 190.
The indexing rod 182 extends under the indexing head 174 and includes two
diametrically opposed fins 192 and 194 mounted in elongated slots 196 and
198 respectively and projecting out of the periphery of the rod portion of
the indexing rod 182 a distance sufficient to engage a pin member 180 when
the indexing rod 182 is rotated. The length of the finned portion of the
indexing rod 182 should be sufficient so that the fins 192 and 194 are
positioned under the indexing head 174 during the entire stroke of the
shear blade head so that each drop guide 150 may be adjusted during the
time the mechanism is running. A spring biased detent member 200 (shown
dotted in FIG. 4) is mounted in each drop guide holder 152 to engage one
of a plurality of slots 202 in the forward face of an index wheel 204
which is attached to the adjusting screw 164 by means of a roll pin 206 or
other suitable connection to prevent relative rotation therebetween. The
cooperation between the detent member 200 and a given slot 202 will
prevent accidental roation of the indexing rod 182 due to vibration or the
like. A chain 208 (shown dotted in FIG. 4) may be connected to the
sprocket member 198 and be of suitable length so that the sprocket member
188 can be turned by an operator standing on the main floor.
With the arrangement just described, each drop guide 150 can be
independently adjusted in a horizontal direction toward and away from the
centerline 149 of an orifice. Rotation of the sprocket member 188 causes
rotation of the indexing head 174 by means of one or the other of the fins
192 or 194 engaging successive pin members 180 upon each 180.degree.
rotation of the indexing rod 182. Rotation of the indexing head 174 causes
the adjusting screw 164 and, thus the drop guide 150, to move horizontally
in a direction along the axis of the adjusting screw 164 relative to the
carriage member 120.
Referring now to FIGS. 1 and 7 in particular, an adjusting shaft 210 may be
provided in connection with each drop guide 150 to pivot the drop guide
150 about the vertical axis of its cap screw 154. The adjusting shaft 210
has a reduced forward end portion 212 received in an aperture 214 in the
drop guide holder 152 and restrained therein in an axial direction by a
retaining ring 216. A nut member 218 is received on a threaded portion 219
of the adjusting shaft 210 and is pivotally attached to lever arm portion
220 of the drop guide 150 by a pivot pin arrangement 221. The adjusting
shaft 210 extends through the carriage member 120 and through an enlarged
opening 222 in the end plate 6. Mounted in the enlarged opening 222 is a
bushing 224 which is attached to the end plate 6 by a screw member 225. A
knob assembly 226 is mounted in the bushing and is retained therein for
relative rotation therewith by means of a shoulder 228 thereon and a
retaining ring 230 as shown in FIG. 7. If desired, a bearing washer 232
may be provided between the retaining ring 230 and the end plate 6 and
also between the shoulder 228 and end plate 6. The outer end portion of
the adjusting shaft 210 may be provided with a keyway 233 to which the
knob assembly 226 may be keyed by a key member 234. The outer surface 236
of the knob assembly 226 which extends out from the frame 2 may be
hexagonal in cross-section so that it may be rotated about its axis by a
hex wrench or other suitable implement.
By virtue of the construction just described, each drop guide 150 may be
adjusted about a vertical axis running through the cap screw 154. When the
knob assembly 226 is rotated, the adjusting shaft 210 is also rotated
because of the keyed connection. Since the adjusting shaft 210 cannot move
axially due to its connection to the drop guide holder 152, rotation of
the adjusting shaft causes the nut member 218 to move to the right or left
(as viewed in FIG. 7) causing the drop guide to pivot about the axis of
the cap screw 154.
The length of the outer end portion of the adjusting shaft 210 which is
provided with the keyway 233 should be sufficiently long so that the shaft
210 remains keyed to the knob assembly 226 during the entire stroke of the
shear head 16. This enables the drop guide 150 to be adjusted toward and
away from a suspended column of molten glass while the mechanism is in
operation. The drop guide serves to guide the severed gob during its
initial downward movement as it is being separated from the suspended
molten glass column. As the lower shear blade 46 passes under the upper
shear blade 132, there is a tendency for the gob, as it is cut or sheared,
to have its upper end moved toward the upper shear head 16 by the lower
blade 46. As the horizontal position of each drop guide 150 is adjustable,
each drop guide 150 can be independently moved to the best guiding
position. Further, if there is a tendency for the gob to be moved by the
lower shear blade 46 in a direction transverse to the direction of
movement of the shear heads 14 and 16, the fact that each drop guide 150
can be independently adjusted about a vertical axis, provides a side
adjustment for the drop guide to control the fall of the gob.
It should be mentioned at this time that the preceding description of the
present invention was made in connection with a mechanism for use with a
double gob feeder. That is, a mechanism for use in connection with a
feeder that feeds two columns of glass and thus, is provided with two sets
of shear blades, both sets acting simultaneously. However, the present
invention, both as previously described, and as described below is
applicable to a single gob apparatus where only one set of blades is
provided, or to one in which more than two are provided, such as a triple
gob apparatus wherein three sets of blades act simultaneously.
In fact, the mechanism as described is easily changed from two sets of
blades as shown to one using either a single set or more than two sets. To
change to a different number of lower shear blades 46, the shear blade
bracket 38 may be removed from the carriage member 28 by removing the
bolts 39. A new bracket previously equipped with the desired number of
shear blades and each blade provided with its adjustment mechanism as
described above can then be attached to the carriage member 28. Indexing
rods 106 will have to be removed or added and spaced as necessary.
Similarly, in the case of the upper shear blades 132, the shear blade
holder 128 may be removed from the carriage member 120 by removing bolts
134. A new holder 128, previously outfitted with the required number of
blades may then be attached. Drop guides 150 will have to be added or
removed as required and their spacing changed as necessary. The carriage
member 120 may have pre-drilled apertures to permit mounting of a drop
guide in single gob and double gob configurations.
The left and right-hand shear heads 14 and 16 are moved toward each other,
through the cutting stroke, and returned to their dwell or retract
position by means of the pneumatic cylinder assembly 18. Referring to
FIGS. 1 and 2, the pneumatic cylinder assembly 18 is mounted on the end
plate 4 by means of a retainer plate 238 which is attached to the cylinder
assembly 18 by means of a nut member 240 threaded onto a threaded boss 241
which extends through an aperture 242 in the retainer plate 238. The
retainer plate 238 is attached to the end plate 4 by suitable screws or
bolts 243 as shown in FIG. 5. The air cylinder assembly 18 includes a
cylinder member 244 in which is mounted a piston member 246 (shown in
dotted lines in FIG. 2). The operating rod 20 is attached to the piston
member 246 and has a forward portion 248 extending out of the cylinder
member 244 toward end plate 6 and a rearward portion 250 extending in an
opposite direction out of the cylinder member 244. Suitable ports 252 and
254 are provided in the cylinder to admit pneumatic fluid such as air to
the rearward and forward sides respectively of the piston as will be
described in more detail below.
The rearward portion 250 of the operating rod 20 extends into a housing 256
attached to the outside of the end plate 4. The housing 256 includes upper
and lower rack guiding sleeves 258 and 260. The rearward portion 250 of
the operating rod 20 extends into the lower rack guiding sleeve 260 and is
attached to a short rack member 262. If desired, the short rack member 262
may be formed directly on the operating rod 20. A rack rod 264 is mounted
in the upper rack guiding sleeve 258 and extends forwardly toward the
right-hand shear blade head 16. The rearward end of the rack rod 264 has
suitable teeth 266 for engaging the teeth 268 of a pinion 270 mounted in
the housing 256 and positioned between the rack rod 264 and short rack
member 262. The short rack member 262 includes suitable teeth 272 for
engaging the teeth 268 of the pinion 270. The pinion 270 is keyed to a
shaft 274 mounted for rotation in the housing 256 along an axis
perpendicular to the axis of the rack rod 264 and rack member 262. The
rearward end of the housing 256 is closed by a rack cover 276 suitable
attached to the cover by bolts 280 or the like.
The rack rod 264 has its forward end reduced, threaded and attached to a
flange portion 282 extending from the tubular portion 124 of the carriage
member 120 of the right-hand, or upper, shear head 16. Washer members 284
are disposed on either side of a flange portion 282 and a lock washer 286
and a nut member 288 are provided to secure the connection. The forward
portion 248 of the operating rod 20 is directly connected to a flange
portion 290 extending from the tubular portion 34 of the carriage member
28 of the left-hand, or lower, shear head 14. The forward end of the
forward portion 248 of the operating rod 20 is reduced, threaded, and
attached to the flange portion 290 by means of washer members 292 disposed
on either side of the flange portion 290, a lock washer 294 and a nut
member 296.
With the above described construction, when pneumatic fluid enters the
cylinder 244 through port 252, the piston member 246 will move to the
right as viewed in FIG. 2, and port 254 will serve as an exhaust port.
Movement of the piston member 246 in this direction causes the left-hand,
or lower, shear head 14 also to mve to the right. At the same time, the
short rack member 262 will cause the pinion 270 to rotate
counter-clockwise, driving the rack rod to the left. This in turn drives
the right-hand, or upper, shear head 16 to the left on the frame 2 toward
the moving left-hand, or upper, shear head 14. This movement of the shear
heads 14 and 16 toward each other continues until the upper shear blades
132 pass over the top of lower shear blades 46 and the cutting stroke is
completed. Pneumatic fluid may then be admitted to the other side of the
piston member 246 through port 254, cause the piston member to return to
its position as shown in FIG. 2 and moving the shear blade heads 14 and 16
away from each other to their retracted or dwell position shown in FIG. 1.
FIGS. 10-14 illustrate the pneumatic control system used to actuate and
control the movement of the shear blade heads 14 and 16. The air cylinder
assembly 18 is represented schematically in FIGS. 10-14 and movement of
the piston member 246 to the right as viewed in these FIGURES represents
the cutting stroke and movement of the piston member to the left
represents the return or retracting stroke.
In general, the pneumatic control system includes a fluid pressure supply
line 300 connected to a tank or receiver 302 through a check valve 304.
The outlet from the tank 302 passes through a lubricator 306 and splits
into three supply lines 308, 310, 312. Line 308 is connected to a first
port 314 of a cushion operator valve 316, which is a three way valve
having a mechanical operator and automatic retract. Port 318 of valve 316
is connected to an exhaust line 320 and port 322 is connected to a cushion
control valve pilot line 324. Valve 316 is of the type that when the valve
is actuated, ports 314 and 322 are interconnected and when the valve is
automatically retracted or unactuated, ports 318 and 322 are
interconnected.
Supply line 310 is connected to a port 325 of a cut-retract operator valve
326. Valve 326 is a spool valve which is pilot operated in one direction
and mechanically operated in the other direction. Valve 326 is provided
with four other ports 328, 330, 332 and 334 arranged to be interconnected
as follows: when the valve 326 has been mechanically actuated (with its
mechanical actuator 336 in the down position as shown in FIG. 10) ports
325 and 332 are interconnected and ports 328 and 330 are interconnected;
and when the valve 326 is pilot operated (which raises the mechanical
actuator as shown in FIG. 11) port 334 is connected to port 332 and port
325 is connected to port 330. An exhaust line 338 is connected to the port
334. Valve 326 may be adjustably mounted to adjust the amount of shear
blade overlap during the cutting stroke as explained more fully below.
The supply line 312 splits into two lines, a cylinder actuating line 340
and a cycle start line 342. The cylinder actuating line 340 is connected
to port 344 in a cut-retract control valve 346. The cut-retract control
valve 346 is a spool valve, pilot operated in both directions. The valve
346 is provided with four additional ports 348, 350, 352 and 354 adapted
to be placed in communication by actuation of the valve 346 as follows:
when pilot line 356 is pressurized as shown in FIG. 10, ports 344 and 352
are interconnected and ports 348 and 350 are interconnected, and when
pilot line 360 is pressurized as shown in FIG. 11, ports 344 and 350 are
interconnected and ports 352 and 354 are interconnected. A piston retract
line 362 connects the ports 352 of the valve 346 to the port 254 of the
cylinder assembly to admit pressure to the right side of the piston member
246 and drive it to the left. A piston advance or cut line 364 connects
port 350 of the valve 346 to the port 252 of the cylinder assembly to
communicate to admit pressure to the left side of the piston member 246
and drive it to the right. An exhaust line 363, having a cutting stroke
speed control needle valve 365 therein, is connected to port 354.
The cycle start line 342 is attached to one port 366 of a cycle start valve
368. The cycle start valve 368 is a three way valve having a mechanical
operator and automatic retract. Port 370 of valve 368 is connected to an
exhaust line 372 and port 374 thereof is connected to a cut-retract
operator valve pilot line 376. Valve 368 is arranged such that when it is
unactuated as shown in FIG. 10 and in its retracted position, port 374 is
interconnected with port 370. When the valve 368 is actuated as shown in
FIG. 11, port 374 is interconnected with port 366. The cut-retract
operator valve pilot line 376 is connected to the pilot actuator of the
cut-retract operator valve 326.
Port 332 of the cut-retract operator valve 326 is connected by a line 378
to a port 380 of an automatic retract-reset valve 382 which is a spool
valve, pilot operated in one direction, manual reset in the other
direction. When the valve 326 is in its reset or normal operating position
as shown in FIG. 10, port 380 is interconnected with a port 384 to which
the pilot line 356 of valve 346 is connected. Valve 382 also includes two
other ports 386 and 388, both of which are connected by branched line 390
to port 330 of the cut-retract operator valve 326. With valve 382 in the
reset position as shown in FIG. 10, port 386 is interconnected with a port
392 to which pilot line 360 of valve 346 is connected. When valve 382 is
pilot actuated as shown in FIG. 14, ports 384 and 388 are interconnected
and ports 380 and 392 are interconnected.
A branch line 394 from the cylinder actuating line 340 is connected to a
port 396 of an automatic retract signal valve 398. Another port 400 of the
valve 398 is connected to an exhaust line 402 and a third port 404 is
connected by a line 406 to a port 408 of an automatic retract operator
valve 410. The automatic retract signal valve 398 is three-way valve,
mechanically operated and automatically reset. The valve 398 is arranged
so that when the valve is in its normal, reset position as shown in FIG.
10, ports 400 and 404 are interconnected and when it is mechanically
actuated, ports 396 and 404 are interconnected.
The automatic retract operator valve 410 includes a second port 412 which
is connected to an exhaust line 414 and a third port 416 connected to an
automatic retract-reset valve pilot line 418 which in turn is connected to
the pilot actuator side of the automatic retract-reset valve 382. Valve
410 is of the mechanically operated, automatic retract type and is
arranged such that when it is in the normal retract position, port 412 is
interconnected with port 416 and when it is actuated, port 408 is
interconnected with port 416.
The port 404 of the automatic retract signal valve 398 also may be
connected to a pressure switch 420 by means of a branch line 422 coming
from line 406. The pressure switch 420 may be used to supply a signal to a
computer or other device for the purpose of counting the number of cutting
strokes of the shear blade heads 14 and 16 as explained below.
In the cycle start line 342 upstream of the cycle start valve 368 and
downstream of line 340, a series of safety valves 424, | | |
