U.S. patent number 3,892,156 [Application Number 05/441,207] was granted by the patent office on 1975-07-01 for knife holders for slitter winding machines and the like.
This patent grant is currently assigned to Johnstone Engineering & Machine Company. Invention is credited to Bruce V. Johnstone.
United States Patent |
3,892,156 |
Johnstone |
July 1, 1975 |
Knife holders for slitter winding machines and the like
Abstract
A pressure fluid operated knife holder comprising a cylinder
having a piston and piston rod therein, and a knife head carried by
the piston rod. The piston, piston rod and knife head assembly are
fluid pressure actuated from an upper limit position to a lower
limit position in which a male knife on the head is positioned
relative to a female knife. Adjustable means is provided for
initially setting the cutting edge of the male knife relative to
the female knife in the lower limit position of the assembly. The
male knife is supported by a mounting axially movable in the knife
head between inner and outer positions to set the male knife in
cutting position against the female knife, and the mounting also
has limited rocking movement to equalize contact pressure between
the male and female knives. Outward axial displacement of the
mounting to set the male knife is accomplished by pressure fluid
from the cylinder and the connections from the cylinder to the
knife head are constructed and arranged so that pressure fluid
cannot flow from the cylinder to the knife head until the assembly
is in the lower limit position. Pressure fluid admitted to the
knife head is vented to atmosphere in all positions of the assembly
except said lower limit position.
Inventors: |
Johnstone; Bruce V. (Gap,
PA) |
Assignee: |
Johnstone Engineering & Machine
Company (Parkesburg, PA)
|
Family
ID: |
23751968 |
Appl.
No.: |
05/441,207 |
Filed: |
February 11, 1974 |
Current U.S.
Class: |
83/469; 83/501;
83/508.1; 83/562; 83/482 |
Current CPC
Class: |
B23D
35/004 (20130101); B26D 5/04 (20130101); Y10T
83/7868 (20150401); Y10T 83/7751 (20150401); Y10T
83/7834 (20150401); Y10T 83/8746 (20150401); Y10T
83/768 (20150401) |
Current International
Class: |
B23D
35/00 (20060101); B26D 5/04 (20060101); B26D
5/02 (20060101); B23D 019/00 (); B26D 001/14 () |
Field of
Search: |
;83/482,501,502,503,562,508.2,469 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Abercrombie; Willie G.
Attorney, Agent or Firm: Howson and Howson
Claims
I claim:
1. A pressure fluid actuated knife holder comprising a cylinder, a
piston rod extending axially through said cylinder beyond the ends
thereof and having a pressure fluid passage extending coaxially
therein, a piston in the cylinder secured on said piston rod,
intercooperating means on the piston rod and the cylinder operable
to determine retracted and projected limit positions of travel of
the piston and rod axially in said cylinder, a knife head on one
end of said piston rod for movement therewith between retracted and
projected positions, knife support means in said knife head axially
shiftable therein between inner and outer positions along an axis
perpendicular to the axis of the cylinder, pressure fluid
actuatable means in the knife head operable to shift said knife
support means from said inner position to an outer position, means
in said knife head defining a pressure fluid passage communicating
between the coaxial pressure fluid passage in said piston rod and
said pressure fluid actuatable means in the knife head, means to
admit pressure fluid to the cylinder to actuate said piston from
said retracted position to said projected limit position, means in
the piston rod adjacent the other end thereof defining a pressure
fluid inlet passage therein having an inner opening communicating
with the coaxial pressure fluid passage in said piston rod and an
outer opening for communication with the cylinder interior, the
outer opening of said pressure fluid inlet passage being disposed
axially in the piston rod so that said outer opening is normally
closed by the cylinder in the intermediate and retracted positions
of the piston rod and is open and in communication with the
cylinder interior only in the projected limit position, and means
in the piston rod defining a vent passage having an inner opening
communicating with said coaxial fluid passage therein and an outer
opening for communication with the external atmosphere, said vent
passage being disposed axially in said piston rod and spaced with
respect to the pressure fluid inlet opening therein so that the
vent outer opening is closed by the cylinder in the projected limit
position of the piston rod and is open to the atmosphere in the
intermediate and retracted limit positions of said piston rod,
whereby pressure fluid can flow from said cylinder to the knife
head to axially shift the knife support from said inner position
only in the projected limit position of the piston rod and the
knife head is vented to atmosphere in said intermediate and
retracted positions of the piston rod.
2. A pressure fluid actuated knife holder as claimed in claim 1
comprising means operable to return the piston and piston rod
together with the knife head from the projected limit position to
the retracted limit position upon cut-off of pressure fluid to the
cylinder.
3. A pressure fluid actuated knife holder as claimed in claim 2
wherein the means for returning the piston and piston rod from the
projected limit position to the retracted limit position comprises
an expansion coil spring circumscribing the piston rod.
4. A pressure fluid actuated knife holder as claimed in claim 1
comprising means operable to return the knife support means to the
inner position thereof in the knife head upon venting pressure
fluid from the latter.
5. A pressure fluid actuated knife holder as claimed in claim 4
wherein the means for returning the knife support means to the
inner position comprises a plurality of expansion coil springs
acting between the knife support means and an adjacent portion of
the knife head.
6. A pressure fluid actuated knife holder as claimed in claim 1
comprising a circular knife journaled in the knife mounting means
for rotation about an axis perpendicular to the axis of the
cylinder, said knife having a circumferential cutting edge.
7. A pressure fluid actuated knife holder as claimed in claim 6
wherein the knife mounting means is constructed and arranged for
limited pivotal rocking movement in the knife head about a center
located on the rotation axis of the knife to permit limited angular
deflection of said knife from said axis.
8. A pressure fluid actuated knife holder as claimed in claim 6
wherein the piston rod includes adjustable means operable to
determine the projected limit position of the piston and piston rod
with respect to the cylinder and thereby predeterminedly set the
projected limit position of the cutting edge of the circular
knife.
9. A pressure fluid actuated knife holder as claimed in claim 8
wherein the adjustable means to determine the projected limit
position of the piston and piston rod comprises an adjustment
member threaded on a portion of the piston rod at the opposite side
of the piston from said knife head and manually adjustable on said
piston rod.
10. A pressure fluid actuated knife holder as claimed in claim 9
wherein the pressure fluid inlet passage from the cylinder interior
to the coaxial pressure fluid passage in the piston rod is in the
adjustment member.
11. A pressure fluid actuated knife holder as claimed in claim 9
wherein the vent passage between the coaxial fluid passage in the
piston rod and the external atmosphere is in the adjustment
member.
12. A pressure fluid actuated knife holder as claimed in claim 10
wherein the vent passage between the coaxial fluid passage in the
piston rod and the external atmosphere is also in the adjustment
member.
13. A pressure fluid actuated knife holder as claimed in claim 7
wherein the limited pivotal rocking movement of the knife mounting
means is provided by a peripheral surface thereon of arcuate
spherical shape having a radius described from the center of
pivotal rocking movement of said knife mounting means.
14. A pressure fluid actuated knife holder as claimed in claim 9
wherein the intercooperating means operable to determine the
retracted and projected limit positions of the piston rod axially
in said cylinder comprises axially spaced means on the adjustment
member disposed for cooperative engagement with the cylinder.
15. A pressure fluid actuated knife holder as claimed in claim 2
comprising means operable to return the knife support means to the
inner position thereof in the knife head upon venting pressure
fluid from the latter.
16. A pressure fluid actuated knife holder as claimed in claim 15
wherein the knife mounting means is constructed and arranged for
limited pivotal rocking movement in the knife head about a center
located on the rotation axis of the knife to permit limited angular
deflection of said knife from said axis.
17. A pressure fluid actuated knife holder as claimed in claim 15
wherein the adjustable means to determine the projected limit
position of the piston and piston rod comprises an adjustment
member threaded on a portion of the piston rod at the opposite side
of the piston from said knife head and manually adjustable on said
piston rod.
18. A pressure fluid actuated knife holder as claimed in claim 15
wherein the vent passage between the coaxial fluid possage in the
piston rod and the external atmosphere is also in the adjustment
member.
19. A pressure fluid actuated knife holder as claimed in claim 16
wherein the vent passage between the coaxial fluid passage in the
piston rod and the external atmosphere is also in the adjustment
member.
20. A pressure fluid actuated knife holder as claimed in claim 19
wherein the limited pivotal rocking movement of the knife mounting
means is provided by a peripheral surface thereon of arcuate
spherical shape having a radius described from the center of
pivotal rocking movement of said knife mounting means.
21. A pressure fluid actuated knife holder as claimed in claim 20
wherein the intercooperating means operable to determine the
retracted and projected limit positions of the piston rod axially
in said cylinder comprises axially spaced means on the adjustment
member disposed for cooperative engagement with the cylinder.
Description
This invention relates to new and useful improvements in knife
holders for slitter winding machines and the like. More
particularly, the invention relates to knife holders of the fluid
pressure actuated type having separate means for lowering the knife
relative to the material to be cut and for laterally setting the
knife relative to the cooperating mating knife of the machine.
Prior knife holders of the type described are characterized by
certain objectionable features and disadvantages. For example, in
some prior knife holders it frequently occurs that the lateral set
or shift of the male knife relative to the female knife of the
machine will commence or take place before the male knife has
reached the full lowered position thereof in proper overlapping
relation to the female knife of the machine thereby causing
premature engagement of the knives with resulting damage to the
male knife. Also, the construction and arrangement of some prior
holders is such that when cutting heavy weight dense board with
taped lapped splices sufficient resistance may be presented to
elevate the male knife when it is laterally set or shifted and the
male knife will engage and ride on the surface of the female knife
as in a score type cut with resulting damage to the male blade.
Another objection to prior knife holders of the aforesaid type is
that the construction and arrangement for mounting the male knife
member causes variations in the contact pressure between the male
and female blades resulting in excessive wear of the blades. Also,
in a number of prior devices it is difficult to remove and replace
the male knife on the knife holder.
With the foregoing in mind, an object of the present invention is
to provide a novel knife holder of the type described that is
constructed and arranged to prevent lateral setting or shifting of
the male knife until the latter has attained its fully lowered
position in proper overlapping relation to the female knife of the
machine.
Another object of the invention is to provide a knife holder of
novel construction in which any tendency for the male knife to
override the female knife of the machine is prevented.
Another object of the present invention is to provide a knife
holder having the features and advantages set forth wherein the
contact pressure between the male and female knives is
substantially constant at all times.
A further object of the invention is to provide a novel knife
holder construction in which removal and replacement of the male
knife may be readily and easily accomplished.
These and other objects of the invention and the various features
and details of the construction and operation thereof and
hereinafter fully set forth and described with relation to the
accompanying drawings, in which:
FIG. 1 is a side elevational view partially in section of a knife
holder embodying the present invention showing the male knife
actuating piston in the raised inoperative position;
FIG. 2 is a front elevational view of the knife holder shown in
FIG. 1;
FIG. 3 is an enlarged fragmentary sectional view on line 3--3, FIG.
2;
FIG. 4 is a fragmentary sectional view of the upper portion of FIG.
3 showing the male knife actuating piston and associated parts in
the fully lowered operative position of the male knife;
FIG. 5 is a fragmentary sectional view on line 5--5, FIG. 3;
FIG. 6 is an enlarged partial sectional view on line 6--6, FIG.
1;
FIG. 7 is a view similar to FIG. 6 showing the male knife and its
supporting head in the fully lowered cutting position; and
FIG. 8 is a sectional view in reduced scale on line 8--8, FIG.
6.
Referring now to the drawings, FIGS. 1-3 thereof, show one
embodiment of the present invention comprising a vertically
disposed cylinder 1 having an integral bracket portion 2 projecting
laterally therefrom constructed and arranged for slidable mounting
on the arbor 3 of a typical slitter winding machine. The bracket 2
is fixedly secured to the arbor 3 by means of a Reid screw 4. The
arbor 3 extends horizontally crosswise of the slitter winder
machine, and customarily a plurality of knife holders is mounted on
the arbor 3 at spaced intervals therealong according to the widths
of the strips into which the web material is to be cut. The
individual knife holders may be adjustably positioned and secured
as desired along the arbor 3 by loosening the Reid screw 4,
grasping the handle 5 and then re-tightening the Reid screw 4.
Referring more particularly to FIG. 3, the cylinder 1 has upper and
lower annular end members 6 and 7, respectively, fixedly secured in
place by means of snap rings 8 and 9. The upper annular end member
6 is provided with an annular packing ring 10 seated in an annular
groove 11 formed in the outer surface of the member 6 and disposed
in sealing engagement with the adjacent inner wall surface of the
cylinder 1. Lining the interior wall of the cylinder 1 between the
cylinder end members 6 and 7 is a tubular cylindrical sleeve 12 in
which is slidably mounted an annular piston 13 of comparatively
short axial length. The piston 13 is provided with piston ring 14
seated in a groove 15 and the ring 14 has sliding sealing
engagement with the inner wall surface of the cylinder sleeve
12.
The annular piston 13 is mounted on a piston rod 16 that extends
coaxially within the cylinder 1 and lining sleeve 12. The piston
rod 16 comprises an intermediate portion 17 that extends through
the annular piston 13 and has an external diameter substantially
the same as the internal diameter of the piston. A lower portion 18
of the piston rod 16 has a larger diameter than the piston portion
17 and provides an annular shoulder 19 on which the piston 13 is
seated and firmly secured on the piston rod 16 by a snap ring 20.
An O-ring type seal 21 is mounted in the portion 17 of the rod 16
adjacent the annular shoulder 19.
The piston rod 16 also comprises an upper portion 23 having a
diameter less than the intermediate portion 17 and a terminal end
portion 24 of less diameter than said portion 23. The rod portion
23 is externally threaded as shown and threaded thereon is the
internally threaded annular skirt portion 25 of an adjustment
thimble 26 that also has a recess 25a of smaller diameter to
receive the terminal end portion 24 of the piston rod 16. The
purpose and operation of the adjustment thimble 26 is hereinafter
set forth. The adjustment thimble 26 extends coaxially through the
annular cylinder end member 6 and is rotatably adjustable axially
on the piston rod 16. A fluid pressure tight seal is provided
between the adjustment thimble 26 and the cylinder end member 6 by
a packing ring 27 recessed in the inner wall surface of said member
6, and a further seal between the end member 6 and thimble 26 is
provided by an O-ring 28 seated in a recess 29 in the upper end
face of the member 6 and circumscribing the external surface of the
adjustment thimble 26.
An expansion spring 30 is coiled about the lower portion 18 of the
piston rod 16 and acts between the lower cylinder end member 7 and
the piston 13 normally to urge said piston 13 and piston rod 16
upwardly to the elevated or inoperative position of the knife
holder shown in FIGS. 1-3 of the drawings. In the illustrated
embodiment of the invention the piston 13 and piston rod 16 are
actuated downwardly within the sleeve 12 of cylinder 1 against the
expansion force of the spring 30 by means of air under pressure
admitted to the cylinder 1 above the piston 13 through a suitable
fitting 31.
As will be apparent from FIGS. 3 and 4 of the drawings, axial
movement of the piston rod 16 in either direction is accompanied by
a corresponding axial movement of the adjustment thimble 26
relative to the annular cylinder end member 6. The upper limit
position of the piston assembly, comprising piston 13, piston rod
16 and adjustment thimble 26, is fixedly determined by a snap ring
32 that is seated in a groove 33 formed in the outer surface of the
skirt portion 25 of the thimble 26 and engages against the
undersurface of the annular cylinder end member 6 as shown in FIG.
3. The adjustment thimble 26 is provided with an enlarged head
portion 34 and the lower limit position of the piston assembly is
fixedly determined by engagement of the undersurface 35 of the
thimble head portion 34 with the adjacent surface of the cylinder
end member 6 as shown in FIG. 4 of the drawings. By this
construction and arrangement the stroke of the piston, rod and
thimble assembly is constant and equal to the axial distance
between the snap ring 32 and the undersurface 35 of the thimble
head portion 34.
Referring to FIGS. 3, 6 and 7 of the drawings, the portion 18 of
the piston rod 16 extends slidably through the annular member 7 at
the lower end of the cylinder 1 and terminates a short distance
therebelow. The piston rod 16 normally is secured against rotation
relative to the annular end member 7 by means of a key 36 mounted
in confronting keyways 37 and 38 provided, respectively, in the
piston rod portion 18 and end member 7, for example, as shown in
FIG. 5 of the drawings. The key member 36 is secured in place by
suitable fastening means such as a screw 39 and the annular end
member 7 is fixedly secured rotationally with respect to the
cylinder 1 by means of a set screw 40.
Secured to the lower end of the piston rod portion 18, for example
by welding 41, is a supporting head 42 for the male knife of the
knife holder. The head 42 is of cylindrical construction having an
axial recess 43 of relatively large diameter defined by a
cylindrical internal wall surface 44 and an axial recess 45 of
smaller diameter defined by the cylindrical internal wall surface
46. The larger recess 43 is partially closed by an annular end ring
47 secured in place, for example, by screws 48 and the recess 45 is
closed by an end plate 49 secured in place, for example by screws
50.
Mounted axially in the head 42 for limited axial and rocking
movement therein is a bearing support, generally designated 51,
comprising an annular member 52 disposed in the recess 43 and a
member 53, secured to the member 52 by screws 54, that projects
axially within the recess 45 and has an external diameter somewhat
less than the diameter of the wall 46 of said recess 45.
The peripheral surface 55 of the bearing support member 52 engages
with the circumscribing cylindrical wall surface 44 of the recess
43 and is provided with an arcuate spherical surface contour as
shown in FIGS. 6 and 7 having a radius described from the center c
located on the axis of the knife head 42.
The member 52 of the bearing support 51 includes an axially
extending annular sleeve portion 56 that projects endwise through
the central opening in the end ring 47 of the head 42, and the stub
shaft 57 of a knife mounting plate 58 is rotationally mounted in
said sleeve 56, for example, by means of a bearing assembly 59. A
male cutting knife 60 is frictionally secured with respect to the
plate 58, for example, by means of a beveled snap ring 62 engaged
in a suitable slot 63 in the mounting plate 58. The bearing
assembly is secured in the sleeve 56, for example, by means of a
snap ring 64 engaged in an internal groove 65 of said sleeve.
Sufficient clearance is provided between the support member 52 and
the end ring 47 of the head 42 to permit limited axial movement of
the support 51 within the head 42 and, of course, any such axial
movement of the support 52 is accompanied by a corresponding axial
movement of the mounting plate 58 and knife 60 carried thereby.
Also, limited rocking movement of the bearing support 51 about the
center c within the head 42 is afforded by the arcuate spherical
peripheral surface 55 on the member 52.
When the male knife 60 is inoperative, the mounting 51 normally is
maintained in the axial inward limit position thereof shown in FIG.
6, by means of a plurality of expansion coil springs 66 arranged in
equally spaced circumferential relation (see FIG. 8) and mounted in
counterbored recesses 67 in the member 52. The springs 66 react
between the inner surface of the end ring 47 and annular shoulders
68 at the inner ends of the recesses 67, and smaller diameter
passage 69 extend from each recess 67 entirely through the member
52 to vent any pressure build-up between the member 52 and head 42
that might tend to oppose actuation of the mounting 51 to the
inward limit position by the springs 66.
Actuation of the mounting 51 and knife 60 axially outward relative
to the head 42 to the operative position shown in FIG. 7 of the
drawings is accomplished by fluid pressure, such as air, admitted
to the head recess 45 and acting upon a flexible diaphragm 70
constructed and arranged as shown more particularly in FIGS. 6 and
7 of the drawings. The central circular portion 71 of the diaphragm
70 is adhesively secured to the adjacent surface of the bearing
support member 53 and the peripheral edge portion 72 of said
diaphragm 70 is fixedly secured in an annular groove or recess 73
provided as shown in the head member 42. The diaphragm 70 also
includes an annular bellows type reversely folded portion 73
surrounding the member 53 and interposed between the latter and the
adjacent circumscribing wall surface 46 of the head member 42.
Pressure fluid is supplied to the recess 45 of the head 42 through
a radial passage 74 formed in the closure plate 49 and terminating
at its outer end in an axial port 75 disposed in confronting
communication with an axial passage 76 formed in the head member 42
and communicating at its inner end with a radial passage 77. At its
outer end the passage 77 in the head member 42 is in open
communication with a coaxial recess 78 provided in the lower end of
the portion 18 of the piston rod 16, and communicating with said
recess 78 is a passage 79 that extends coaxially within the piston
rod 16 for the entire length thereof as shown in FIG. 3 of the
drawings, the upper end of the passage 79 at the tip of the
terminal end portion 24 of the piston rod 16 is in open
communication with the recess 25a of the adjustment thimble 26.
As previously stated, a particular feature of the present invention
is the provision of a knife holder construction of the type
described in which lateral setting of the knife is positively
prevented and cannot occur until the knife has been actuated to its
fully lowered position in proper overlapping relation with the
cooperating female knife of the machine. According to the invention
this is accomplished by constructing and arranging the inlet port
for the flow of pressure fluid from the cylinder 1 to the diaphragm
chamber 45 so that said port is opened to receive pressure fluid
from the cylinder 1 only when the piston 13, rod 16 and knife head
42 have been actuated to the lower limit position. Provision is
also made to vent the diaphragm chamber 45 to atmosphere at all
times except in the lower limit position of the piston
assembly.
In the illustrated embodiment of the invention, a radial port 80 to
receive pressure fluid from the cylinder 1 is provided in the
external wall of the adjustment thimble 26 and is spaced vertically
below the undersurface 35 of the thimble head 34 a predetermined
distance slightly greater than the thickness of the cylinder end
member 6. By this construction and arrangement it will be apparent
that the port 80 is open to the interior of the cylinder 1 to
receive pressure fluid only in the lower limit position of the
piston, rod and thimble assembly determined by the under surface 35
of the thimble head 34, as shown in FIG. 4 of the drawings.
The radial port 80 at the inner end thereof communicates with a
vertical passage 81 in the wall of the thimble 26 and this passage
81 communicates at its upper end with a radial passage 82. The
radial passage 82 extends entirely through the thimble wall
immediately below the head 34 of the thimble 26 and provides a vent
for pressure fluid from the thimble chamber 25a to the ambient
atmosphere except in the lower limit position of the thimble in
which the outer end of the vent passage 82 is closed by the seal 28
in the cylinder end member 6 as shown in FIG. 4.
By virtue of the construction and arrangement shown and described,
pressure fluid admitted to the cylinder 1 through fitting 31 cannot
enter the port 80 and flow through the connecting passages and
ports to the diaphragm actuating chamber 45 in the head 42 until
after the pressure fluid in the cylinder has actuated the piston
rod and thimble assembly to the lower limit position thereof shown
in FIG. 4 of the drawings. In the upper limit position of said
assembly shown in FIG. 3, and in all intermediate positions
thereof, the port 80 is closed to communication with the cylinder 1
and the vent passage 82 is open to the ambient atmosphere.
Thus, at the end of a slitting operation during which the piston -
knife head assembly is in the lower limit position upon cut-off of
the pressure fluid supply to the cylinder 1, the spring 30 in the
cylinder 1 will actuate the piston-knife-head assembly to the upper
limit position shown in FIG. 3. At the start of upward movement of
the piston-knife-head assembly the vent port 82 will be opened to
atmosphere and pressure fluid in the diaphragm actuating system
will immediately be vented to the atmosphere so that the springs 66
immediately return the knife 60 and mounting 51 axially to the
inner limit position thereof as shown in FIG. 6.
In operation of a knife holder embodying the present invention it
is essential that all such devices in the slitter-winding machine
be initially adjusted to bring the edge of the male knife 60 of
each holder into proper overlapping relation with respect to its
cooperating female knife 83. In the illustrated embodiment of the
invention this is accomplished by manually exerting downward
pressure on the thimble head 34 and actuating the piston-knife head
assembly to the lower limit position thereof previously described.
While held in the lower limit position, the thimble 26 is rotated
either clockwise or counter-clockwise as may be required, for
example, be means of a spanner wrench engaged in one of the
recesses 34a provided in the lateral peripheral surface of the
thimble head 34.
Rotation of the adjustment thimble 26 as described operates to
effect vertical adjustment of the piston 13 and piston rod 16
coaxially within the cylinder 1 and a corresponding vertical
adjustment of the knife head 42 and knife 60 relative to the
cooperating female knife 83. Normally, it is desirable that in the
lower limit position of the knife 60 the cutting edge thereof
overlaps the circumference of the female knife 83 a predetermined
distance, for example, about 1/6 inch, as shown in dotted lines in
FIG. 6 of the drawings. This adjustment may just be made separately
for each knife holder in the machine since the radius of the knife
in each holder will vary from holder to holder due to frequent
resharpening and periodic replacement of the male knifes 60 as the
result of wear.
After the male knives 60 of all of the knife holders in the machine
have been adjusted and set as described, the machine is placed in
operation and pressure fluid such as air is admitted through
fitting 31 to the cylinder 1 thereby actuating the piston-knife
head assembly to the lower limit position shown in FIG. 4 wherein
the cutting edge of the blade 60 is disposed in the dotted line
position shown in FIG. 6. As the piston-knife head assembly reaches
its lower limit position the port 80 is opened and pressure fluid
in the cylinder 1 flows through the connecting passages and ports
to the chamber 45 in the knife head 42 thereby actuating the
flexible diaphragm 70 to cause axial displacement of the mounting
51, plate 58 and male knife 60 from the inoperative position shown
in FIG. 6 of the drawings to the operative position thereof shown
in FIG. 7, in which the cutting edge of the male knife 60 is
brought into cutting engagement with the web material w and the
cooperating female knife 83.
Engagement of the cutting edge of the male knife 60 with the
cooperating female knife 83 causes a slight angular deflection of
the male knife 60 from the horizontal axis x to the axis y as shown
in FIG. 7 causing a corresponding rocking movement of the mounting
51 relative to the knife head 42 as shown in FIG. 7 of the
drawings. This rocking movement of the mounting 51 eliminates
variations in the contact pressure between the male and female
knives so that the contact pressure therebetween is substantially
constant at all times.
Upon completion of the slitting and winding operation of the
machine the supply of pressure fluid to the cylinder 1 is cut off
thereby permitting the spring 30 to move the piston-knife head
assembly toward and to the upper limit position thereof and
immediately vent pressure fluid in the diaphragm actuating chamber
through the vent passage 82 in the adjustment thimble 26, thereby
causing the springs 66 immediately to return the mounting 51, plate
58 and male knife 60 axially inwardly of the head 42 to the
position shown in FIG. 6 of the drawings.
From the foregoing it will be apparent that the present invention
provides a knife holder of novel construction and arrangement in
which lateral setting or shifting of the male knife is prevented
and cannot take place until said male knife has attained its fully
lowered position in proper overlapping relation to the female knife
of the machine. The invention also provides a knife holder of novel
construction and arrangement wherein the contact pressure between
the male and female knives is substantially constant at all times
and in which any tendency for the male knife to override the female
knife is eliminated. The invention also provides a construction in
which the removal and replacement of the male knife may be readily
and easily accomplished.
While a particular embodiment of the invention has been illustrated
and described, it is not intended to limit the invention to such
disclosure and changes and modifications may be made therein and
thereto within the scope of the appended claims.
* * * * *