Mechanism for establishing clearance between seaming cam lever and housing of can end double-seaming machine

A can end double-seaming machine has a housing in which a shaft is rotatably supported. The shaft with a seaming cam lever mounted is pressed downwardly by a presser against the bias of a spring until the lower surface of the seaming cam lever is held against the upper surface of the housing. Then, an annular spacer is fitted over the lower end portion of the shaft underneath, with the tubular support held against a neck of the shaft. A seaming roll lever is then mounted on the lower end portion of the shaft. The presser is deactivated to release the shaft, which is lifted together with the seaming cam lever, the annular spacer, and the seaming roll lever under the bias of the spring until the marginal portion of the annular spacer abuts against the lower surface of the housing. The tubular support enters the housing by a distance corresponding to a predetermined clearance. The seaming cam lever and the housing are now spaced from each other by the predetermined clearance.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a mechanism for establishing the clearance 
between a housing and a seaming cam lever for swinging a pair of seaming 
rolls in a machine for double-seaming, a can end on a can body. 
2. Description of Background Art 
Can end double-seaming machines generally have, as major components, a 
lifter, a seaming chuck, and a seaming roll. When a can end is to be 
seamed on a can body, the cam body which is supported on the lifter and 
the can end which is placed on the can body with the seaming chuck fitted 
therein are held between the seaming chuck and the lifter. Then, the 
seaming roll is moved toward the seaming chuck, seaming the can end on the 
can body by plastically deforming a cover hook of the can end and a flange 
of the can body in interengaging relationship to each other. The seaming 
roll comprises first and second seaming rolls. The first seaming roll 
effects a first stage of seaming, and then the second seaming roll effects 
a second stage of seaming, thereby double-seaming the can end on the can 
body. 
FIG. 4 shows a known mechanism (hereinafter referred to as a seaming roll 
mechanism) including the seaming roll of the double-seaming machine. 
The seaming roll mechanism comprises a housing a rotatable around a main 
shaft (not shown) of the doubleseaming machine, and an angularly movable 
shaft b extending vertically through a hole a1 defined in a marginal edge 
portion of the housing a and extending between upper and lower surfaces of 
the housing a. The shaft b has an upper end b1 projecting above the upper 
surface of the housing a, and a seaming cam lever c is integrally fitted 
over the projecting end b1 of the shaft b. The shaft b also has a lower 
end b2 projecting below the lower surface of the housing a, and a seaming 
roll lever d is integrally fitted over the projecting end b2. The seaming 
lever c, the shaft b, and the seaming roll lever d are normally urged 
upwardly by a spring e inserted in an upper portion of the housing and 
held against the seaming cam lever c through a plug f. 
A pair of roll pins g is vertically inserted in the seaming lever d at 
positions one on each side of the shaft b. The roll pins g have lower ends 
projecting below the seaming roll lever d, and first and second seaming 
rolls h, i are rotatably fitted over the projecting lower ends of the roll 
pins g. The seaming roll lever d is threaded over the lower end b2 of the 
shaft b. A lock screw j is threaded through a side of the seaming roll 
lever d toward the shaft b, and has a tip end pressed against the bottom 
of a recess k which is defined in a side of the lower end of the shaft b, 
thereby fixing seaming roll lever d to the shaft b. A pair of washers l is 
interposed between the upper surface of the seaming roll lever d and the 
lower surface of the housing a, the washers l being disposed around the 
shaft b. 
The seaming cam lever c has a cam follower pin n that is vertically fixed 
to a distal end of an arm m which extends horizontally from a portion of 
the seaming cam lever c which is securely fitted over the upper end of the 
shaft b. A cam follower o is rotatably mounted on the cam follower pin n 
by bearings r. The cam follower o is rollingly disposed in a cam groove q 
which is defined in a cam frame p that is positioned above the housing a. 
The cam groove q extends around the main shaft of the doubleseaming 
machine such that when the housing a and the shaft b are angularly moved 
around the main shaft, the cam groove q guides the cam follower pin n to 
turn the shaft b around the axis thereof. As the housing a is angularly 
moved around the main shaft, the seaming cam lever c is turned by the cam 
follower o riding in the cam groove q to angularly move the shaft b to 
turn the seaming roll lever d, thus angularly moving the first and second 
seaming rolls h, i successively toward the seaming chuck s. 
The shaft b is disposed in the housing a with bushings u, v interposed 
therebetween. An expandable and contractable O-ring x is interposed 
between the lower end of the lower bushing v and the upper washer l. 
Normally, there is a clearance Cl between the lower surface of the seaming 
cam lever c and the upper surface of the housing a. The clearance Cl 
allows the seaming cam lever c to move smoothly with respect to the 
housing a even when the seaming cam lever c is thermally expanded while 
operating at high speed during operation of the double-seaming machine. 
As shown in FIG. 5, it is generally necessary to keep the seaming roll h, i 
and the seaming chuck s vertically spaced by a gap t of several tens .mu.m 
in order to avoid mutual interference between the seaming rolls h, i and 
the seaming chuck s when the seaming rolls h, i and the seaming chuck s 
approach each other, thereby allowing the can end to be seamed 
appropriately on the can body. When shaft b turns the seaming roll lever 
d, the shaft b may be depressed under the bias of the spring e. Therefore, 
the clearance Cl should be set up with the same accuracy as that for the 
gap t so that the clearance Cl will not adversely affect the gap t. 
Heretofore, the clearance Cl has been set to a desired magnitude by 
manually adjusting the seaming roll lever d with respect to the shaft b 
when the seaming roll lever d is to be fixedly mounted on the shaft b. 
More specifically, the shaft b with the seaming cam lever c attached to the 
upper end thereof is inserted vertically through the housing a. Then, 
while the shaft b and the seaming cam lever c are being lowered against 
the bias of the spring e, the seaming roll lever d is threaded over the 
lower end of the shaft b. To establish the clearance Cl, the seaming roll 
lever d is threaded up to a suitable position on the lower end of the 
shaft b. Thereafter, the seaming roll lever d is brought against the lower 
surface of the housing a through the washers l under the resiliency of the 
spring e. In order to set up the gap t as well as the clearance Cl, the 
threaded position of the seaming roll lever d is adjusted while measuring 
the gap t and the clearance Cl with a thickness gage, a dial gage, or the 
like. After such adjustment, the seaming roll lever d is secured to the 
shaft b by the lock screw j. 
Therefore, it has been customary to adjust the gap t between the seaming 
rolls h, i and the seaming chuck s below the housing a while measuring the 
gap t with a thickness gage or the like, and also to adjust the fixed 
position of the seaming roll lever d with respect to the shaft b below the 
housing a while measuring the clearance Cl with a dial gage or the like. 
Consequently, it has been cumbersome and time-consuming to establish the 
clearance Cl, and it has taken a long period of time to install the 
seaming roll lever d in position. 
SUMMARY OF THE INVENTION 
In view of the foregoing drawbacks of the conventional can end 
double-seaming machine, it is an of the present invention to provide a 
mechanism for easily setting a clearance between a seaming cam lever and a 
housing to a desired magnitude and also for installing a seaming roll 
lever efficiently in a relatively short period of time. 
According to the present invention, the above object can be achieved by a 
can end double-seaming machine comprising a housing having a vertical hole 
defined therein and extending between upper and lower surfaces thereof, a 
shaft rotatably extending through the vertical hole and having upper and 
lower end portions projecting from the upper and lower surfaces, 
respectively, of the housing, and a neck on the lower end portion thereof, 
a seaming cam lever mounted on the upper end portion of the shaft for 
rotation therewith about an axis of the shaft, a seaming roll lever 
mounted on the lower end portion of the shaft for rotation therewith about 
the axis of the shaft, a pair of seaming rolls rotatably mounted on a 
lower end of the seaming roll lever, biasing means in the housing, for 
normally urging the shaft, the seaming roll lever, and the seaming cam 
lever upwardly, and a mechanism for establishing a predetermined clearance 
between a lower surface of the seaming cam lever and the upper surface of 
the housing. The mechanism comprises an annular spacer disposed around the 
shaft between the seaming roll lever and the lower surface of the housing, 
the annular spacer comprising a marginal portion held against the lower 
surface of the housing with the seaming roll lever, the shaft, and the 
seaming cam lever being urged upwardly by the biasing means, and a tubular 
support disposed around the shaft and projecting integrally from the 
marginal portion toward the hole in the housing, the shaft being supported 
on the tubular support through the neck with the seaming cam lever spaced 
from the upper surface of the housing by a predetermined clearance while 
the marginal portion is being held against the lower surface of the 
housing. The mechanism also comprises pressing means for pressing the 
shaft downwardly until the lower surface of the seaming cam lever is held 
against the upper surface of the housing when the annular spacer is 
disposed around the shaft and the seaming roll lever is mounted on the 
lower end portion of the housing. 
To mount the seaming roll lever on the lower end portion of the shaft, the 
shaft with the seaming cam lever mounted is inserted through the hole in 
the housing, and pressed downwardly by the pressing means against the bias 
of the biasing means until the lower surface of the seaming cam lever is 
held against the upper surface of the housing. Then, the annular spacer is 
fitted over the lower end portion of the shaft underneath the housing, 
with the tubular support being brought into abutting engagement with the 
neck of the shaft. Thereafter, the seaming roll lever is mounted on the 
lower end portion of the shaft. 
Subsequently, the pressing means is inactivated to release the shaft, which 
is lifted together with the seaming cam lever, the annular spacer, and the 
seaming roll lever under the bias of the biasing means until the marginal 
portion of the annular spacer abuts against the lower surface of the 
housing. At this time, with the marginal portion of the annular spacer 
being held against the lower surface of the housing, the tubular support 
enters the hole in the housing by a distance corresponding to a 
predetermined clearance. The lower surface of the seaming cam lever and 
the upper surface of the housing are now spaced from each other by the 
predetermined clearance.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As shown in FIG. 1, a seaming roll mechanism generally comprises a housing 
a, a shaft b, a seaming cam lever c, a seaming cam lever d, first and 
second seaming rolls h, i, and a spring e for normally urging the shaft b 
and components combined therewith. These components of the seaming roll 
mechanism are basically identical to those of the seaming roll mechanism 
shown in FIG. 4. Those parts shown in FIG. 1 which are identical to those 
shown in FIG. 4 are denoted by identical reference characters, and will 
not be described in detail. 
The seaming roll mechanism shown in FIG. 1 additionally has a clearance 
establishing mechanism 1 according to the present invention. 
The clearance establishing mechanism 1 comprises an annular spacer 4 
composed of a pair of lower and upper annular discs 2, 3 fitted 
concentrically over a lower end portion of the shaft b, and a presser 5 
for pressing the shaft b together with the seaming cam lever c and the 
seaming roll lever d downwardly. 
As shown in FIG. 2, the lower annular disc 2 of the annular spacer 4 has a 
tubular support 6 insertable in a central hole defined in the upper 
annular disc 3 and projecting concentrically upwardly from an inner 
peripheral edge of the upper surface of a marginal portion 2a of the lower 
annular disc 2. The upper annular disc 3 is fitted concentrically over the 
tubular support 6 and has a lower surface held against the upper surface 
of the marginal portion 2a of the lower annular disc 2 around the annular 
support 6. 
The annular support 6 has an upper end projecting upwardly from the upper 
surface of the upper annular disc 3 by a distance Cl. 
The shaft b has a neck bx on its lower end portion, the neck bx having a 
smaller diameter than the outside diameter of the shaft b. With the shaft 
b lowered until the seaming cam lever c held against the upper surface of 
the housing a, the annular spacer 4 can be fitted over the lower end 
portion of the shaft b which projects downwardly from the housing a until 
the upper end of the tubular support 6 abuts against the neck bx. The 
distance by which the tubular support 6 projects upwardly from the upper 
surface of upper annular disc 3 is selected to allow a gap, which is the 
same as the clearance Cl to be provided between the seaming cam lever c 
and the housing a, to be formed between the upper surface of the upper 
annular disc 3 and the lower surface of the housing a with the shaft b 
being lowered until the seaming cam lever c is held against the upper 
surface of the housing a. Therefore, the annular support 6 has a height l1 
which is greater than the thickness l2 of the annular disc 3 by the 
clearance Cl. 
The presser 5 comprises an air piston and cylinder assembly fixedly mounted 
on the cam frame p directly above the shaft b and extending axially 
aligned with the shaft b. The air piston and cylinder assembly 5 has a 
piston rod 7 movably extending toward the shaft b. When the piston rod 7 
is extended, it engages the upper end of the shaft b and lowers the shaft 
b against the bias of the spring e until the seaming cam lever c abuts 
against the upper surface of the housing a. 
The clearance establishing mechanism 1 operates as follows: 
To mount the seaming roll lever d on the shaft b, the shaft b with the 
seaming cam lever c mounted thereon is lowered by the air piston and 
cylinder assembly 5 as described above. Then, the annular spacer 4 is 
fitted over the lower end portion of the shaft b, and the tubular support 
6 is brought into abutting engagement with the neck bx of the shaft b. 
Thereafter, the seaming roll lever d is threaded over the externally 
threaded lower end portion of the shaft b until the upper surface of the 
seaming roll lever d is held against the lower surface of the annular 
spacer 4. At this time, the annular spacer 4 is horizontally sandwiched 
between the neck bx of the shaft b and the seaming roll lever d. Now, a 
gap, which is the same as the clearance Cl to be formed between the 
seaming cam lever c and the housing a, is formed between the upper surface 
of the upper annular disc 3 and the lower surface of the housing a. 
Then, the air piston and cylinder assembly 5 is deactivated to release the 
shaft b. The shaft b, the seaming cam lever c, the seaming roll lever d, 
and the annular spacer 4 are lifted in unison under the bias of the spring 
e until the upper surface of the annular disc 3 is engaged by the lower 
surface of the housing a. The shaft b is now supported on the tubular 
support 6 through the neck bx. The tubular support 6 is positioned within 
an annular space defined by the diameter of the neck bx. At this time, 
since the tubular support 6 moves upwardly and enters the hole a1 in the 
housing a by a distance which is equal to the clearance Cl to be provided 
between the seaming cam lever c and the housing a, the seaming cam lever c 
is lifted off the upper surface of the housing a by the clearance Cl of 
predetermined magnitude, i.e., the seaming cam lever c is spaced from the 
upper surface of the housing a by the clearance Cl. 
Therefore, the clearance Cl can automatically be established between the 
seaming cam lever c and the housing a. It is not necessary to make special 
manual adjustments with respect to the seaming roll lever d, and hence the 
seaming roll lever d can be mounted in position within a short period of 
time. 
FIG. 3 shows a single annular spacer according to another embodiment of the 
present invention, which is a unitary combination of the annular discs 2, 
3 of the annular spacer shown in FIG. 2. 
In the embodiment shown in FIG. 2, the annular disc 3 should preferably be 
made of a metallic material, e.g., bronze with phosphor added (ALBC2), 
which allows the annular disc 3 to slide against the housing a, and the 
annular disc 2 should preferably be made of a metallic material, e.g., 
stainless steel (SUS303), which is highly resistant to wear. 
Although certain preferred embodiments of the present invention have been 
shown and described in detail, it should be understood that various 
changes and modifications may be made therein without departing from the 
scope of the appended claims.