U.S. patent application number 09/821150 was filed with the patent office on 2001-11-22 for process and apparatus for producing an endless seamed belt.
This patent application is currently assigned to Xerox Corporation. Invention is credited to Hammond, William A., Schlueter, Edward L. JR., Thornton, Constance J., Yu, Robert C. U..
Application Number | 20010042427 09/821150 |
Document ID | / |
Family ID | 21711734 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010042427 |
Kind Code |
A1 |
Yu, Robert C. U. ; et
al. |
November 22, 2001 |
Process and apparatus for producing an endless seamed belt
Abstract
A novel method and apparatus for producing an endless flexible
seamed belt using templates is disclosed. A first form of the
template is a mask template with a template aperture in the form of
a puzzle cut pattern to be used in combination with an excimer
laser. The template is placed between the excimer laser source and
the belt material to be cut. As the excimer laser traverses the
width of the belt, the laser forms a puzzle cut pattern on the
belt. A second form of the template is a punch and die having
patterned edges in the form of a puzzle cut pattern with extremely
small nodes and kerfs. The cutting tolerances of the patterned
edges make it necessary to fix the punch with respect to the die so
that there is no misalignment of the punch and die between cutting
operations. This is accomplished by resiliently fixing the punch to
the die, rather than having the punch attached to the force
generating assembly as in normal punch and die assemblies. Belt
material is positioned between a stock gap between the punch and
die and the force generating assembly is activated to provide the
cutting force. Once the belt material is cut, the cutting force is
removed and the force generating assembly returns to its retracted
position. Both types of templates result in very clean cuts without
deformation or distortion.
Inventors: |
Yu, Robert C. U.; (Webster,
NY) ; Hammond, William A.; (Rochester, NY) ;
Schlueter, Edward L. JR.; (Rochester, NY) ; Thornton,
Constance J.; (Ontario, NY) |
Correspondence
Address: |
Patent Documentation Center
Xerox Corporation
Xerox Square, 20th Floor
100 Clinton Ave. S.
Rochester
NY
14644
US
|
Assignee: |
Xerox Corporation
|
Family ID: |
21711734 |
Appl. No.: |
09/821150 |
Filed: |
March 29, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09821150 |
Mar 29, 2001 |
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09493445 |
Jan 28, 2000 |
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09493445 |
Jan 28, 2000 |
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09004636 |
Jan 8, 1998 |
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Current U.S.
Class: |
83/145 ;
219/121.18; 29/428; 83/13; 83/620; 83/686; 83/690 |
Current CPC
Class: |
B29C 65/484 20130101;
B29C 66/71 20130101; B29C 65/483 20130101; Y10T 83/8831 20150401;
B29C 66/71 20130101; B29C 66/8242 20130101; B29C 66/71 20130101;
B29C 66/2272 20130101; Y10T 29/49826 20150115; Y10T 83/9425
20150401; B29C 66/71 20130101; B29C 66/71 20130101; B29C 65/4815
20130101; B29C 66/71 20130101; Y10T 83/943 20150401; B29C 66/49
20130101; B29C 65/56 20130101; B29C 66/71 20130101; B29C 66/4322
20130101; B26D 3/10 20130101; B29C 66/71 20130101; B29C 66/71
20130101; Y10T 83/217 20150401; B29K 2067/00 20130101; B29K 2075/00
20130101; B29K 2023/12 20130101; B29K 2083/00 20130101; B29K
2033/12 20130101; B29K 2023/06 20130101; B29K 2023/16 20130101;
B29K 2077/00 20130101; B29K 2069/00 20130101; B29K 2021/00
20130101; B29K 2023/00 20130101; B29K 2027/06 20130101; B29K
2033/08 20130101; B29K 2079/08 20130101; B29C 66/2274 20130101;
B29K 2027/12 20130101; B29C 66/8322 20130101; Y10T 83/2137
20150401; Y10T 83/944 20150401; B29C 66/855 20130101; Y10T 83/9437
20150401; B29C 66/02241 20130101; B29C 66/71 20130101; Y10T 83/0448
20150401; B29C 66/4324 20130101; Y10T 83/9428 20150401; B29C 66/71
20130101; Y10T 83/04 20150401; B29C 66/71 20130101; B29C 66/71
20130101; B29C 66/71 20130101; B29C 66/1142 20130101; B29C 66/12425
20130101; B29C 66/71 20130101; B29C 66/71 20130101; F16G 3/10
20130101 |
Class at
Publication: |
83/145 ; 83/13;
83/620; 83/686; 83/690; 29/428; 219/121.18 |
International
Class: |
B26D 007/00 |
Claims
We claim:
1. A method of making an endless flexible seamed belt from belt
material stock comprising: positioning a template above the belt
material stock; applying a cutting force to the template to form a
first patterned end and a second patterned end on the belt stock
material; and removing the cutting force, wherein the first and
second patterned ends of the belt are cut in a puzzle cut pattern
with mutually mating elements which fit together to form a seam
when joined mechanically to enable the endless flexible seamed belt
to essentially function as an endless belt having a substantially
uniform thickness.
2. The method of making an endless flexible seamed belt as claimed
in claim 1, wherein the cutting force is an excimer laser.
3. The method of making an endless flexible seamed belt as claimed
in claim 2, wherein the template is a metal plate with a template
aperture through which the excimer laser passes to form the first
and second patterned ends on the belt material.
4. The method of making an endless flexible seamed belt as claimed
in claim 3, wherein a first end of one belt and the second end of
another belt are formed in the same cutting force application
step.
5. The method of making an endless flexible seamed belt as claimed
in claim 1, wherein the template is a punch assembly with a die
assembly associated therewith, the punch assembly including a punch
with a first punch cutting end having a first punch pattern and a
second punch cutting end having a second punch pattern and the die
assembly including a die with a first die cutting end having a
first die pattern that is complementary to the first punch pattern
and a second die cutting end having a second die pattern that is
complementary to the second punch pattern; and the cutting force is
applied by a force generating assembly to a force receiving surface
on the punch assembly so that the die and punch cut the belt
material to form a first patterned end on a first end of the belt
and a second patterned end formed on a second end of the belt.
6. The method of making an endless flexible seamed belt as claimed
in claim 5, wherein applying the cutting force further comprises:
forming a first edge on the belt with a first punch cutting edge
interacting with a first die cutting edge; and forming a second
edge on the belt with a second punch cutting edge interacting with
a second die cutting edge, wherein the length of the first and
second edges determine the length of the belt.
7. The method as claimed in claim 6, wherein the removing the
cutting force step further comprises: forming a gap between the
force generator assembly and the force receiving surface of the
punch assembly which allows the force generator assembly to move a
greater distance than the force receiving surface.
8. The method as claimed in claim 6, further comprising: fixing the
punch assembly to the die assembly to limit the movement of the
punch with respect to the die.
9. The method as claimed in claim 8, wherein the punch moves from
about 0.05 inches to about 0.2 inches with respect to the die.
10. An apparatus for producing an endless flexible seamed belt from
belt material stock comprising; a template with a puzzle cut
pattern formed thereon positioned above the belt material stock; a
cutting force applied to the template to form a first patterned end
and a second patterned end on the belt stock material, wherein the
first and second patterned ends of the belt are cut in a puzzle cut
pattern with mutually mating elements which fit together to form a
seam when joined mechanically to enable the endless flexible seamed
belt to essentially function as an endless belt having a
substantially uniform thickness.
11. The apparatus for producing an endless flexible seamed belt as
claimed in claim 10, wherein the cutting force is an excimer laser
and the template has a template aperture through which the excimer
laser passes prior to being absorbed by the belt material to form
the puzzle cut pattern.
12. The apparatus for producing an endless flexible seamed belt as
claimed in claim 10, wherein the template is a punch assembly
including a punch with a first punch cutting end having a first
punch pattern and a second punch cutting end having a second punch
cutting pattern; a die assembly including a die with a first die
cutting end having a first die pattern which is complementary to
the first punch pattern and a second die pattern which is
complementary to the second punch pattern; the cutting force is
generated by a force generating assembly in a cutting operation in
which the punch and die cut the belt material.
13. The apparatus for producing an endless flexible seamed belt as
claimed in claim 12, further comprising: a first edge formed on the
belt with a first punch cutting edge interacting with a first die
cutting edge; and a second edge formed on the belt with a second
punch cutting edge interacting with a second die cutting edge,
wherein the length of the first and second edges determine the
length of the belt.
14. The apparatus for producing an endless flexible seamed belt as
claimed in claim 12, further comprising: a force generator surface
on the force generating assembly that transmits the force of the
force generating assembly to the punch assembly; a force receiving
surface on the punch assembly for receiving the force of the force
generating assembly; and a gap formed between the force generator
surface and the force receiving surface when the force generating
assembly is in a retracted position so that the punch assembly is
disconnected from the force generating assembly.
15. The apparatus as claimed in claim 10, further comprising: a
punch return assembly that resiliently fixes the punch assembly to
the die assembly.
16. An apparatus as claimed in claim 15, the punch return assembly
comprising: at least two bolts connecting the die and punch
assemblies together; and at least two springs, one spring mounted
on each bolt, the springs biasing the punch towards the force
generator and the bolts limiting the movement of the punch in the
direction towards the force generator so that a space from about
0.05 inches to 0.2 inches is formed between the punch and die when
the cutting force is removed.
17. An endless flexible seamed belt made by an apparatus
comprising: a template with a puzzle cut pattern formed thereon
positioned above the belt material stock; a cutting force applied
to the template to form a first patterned end and a second
patterned end on the belt stock material, wherein the first and
second patterned ends of the belt are cut in a puzzle cut pattern
with mutually mating elements which fit together to form a seam
when joined mechanically to enable the endless flexible seamed belt
to essentially function as an endless belt having a substantially
uniform thickness.
18. The endless flexible seamed belt as claimed in claim 17,
wherein the template is a the cutting force is an excimer laser and
the template has a template aperture through which the excimer
laser passes prior to being absorbed by the belt material to form
the puzzle cut pattern.
19. The endless flexible seamed belt as claimed in claim 17,
wherein the template is a punch assembly including a punch with a
first punch cutting end having a first punch pattern and a second
punch cutting end having a second punch cutting pattern; a die
assembly including a die with a first die cutting end having a
first die pattern which is complementary to the first punch pattern
and a second die pattern which is complementary to the second punch
pattern; and the cutting force is generated by a force generating
assembly in a cutting operation in which the punch and die cut the
belt material.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] Attention is hereby directed to U.S. patent application Ser.
No. 08/297,200 (D/94226) entitled "Puzzle Cut Seamed Belt", now
U.S. Pat. No. 5,514,436, issued May 7, 1996; U.S. patent
application Ser. No. 08/297,158 (D/93563) entitled "Puzzle Cut
Seamed Belt With Strength Enhancing Strip", now continuing U.S.
patent application Ser. No. 08/522,622, filed Aug. 31, 1995; U.S.
patent application Ser. No. 08/297,201 (D/94225) entitled "Puzzle
Cut Seamed Belt With Bonding Between Adjacent Surface By UV Cured
Adhesive", now U.S. Pat. No. 5,487,707, issued Jan. 30, 1996; U.S.
patent application Ser. No. 08/297,206 (D/94226Q) entitled "Endless
Seamed Belt with Low Thickness Differential Between the Seam and
the Rest of the Belt", allowed, but not yet issued; and U.S. patent
application Ser. No. 08/297,203 (D/94227) entitled "Puzzle Cut
Seamed Belt with Bonding Between Adjacent Surfaces", all commonly
assigned to the assignee of the present invention and filed on Aug.
29, 1994.
[0002] This invention relates generally to a process and apparatus
for producing an endless seamed flexible belt, and more
particularly concerns forming the ends of the flexible belt in a
puzzle cut pattern which interlock to form a very low profile
seam.
[0003] Initially, flexible belts were fabricated by taking two ends
of a web material and fastening them together by a variety of
techniques such as sewing, wiring, stapling, providing adhesive
joints, etc. While such joined or seamed belts are suitable for
many applications, such as the delivery of rotary motion from a
source such as a motor, to implement a device such as a saw blade,
they are not as satisfactory in many of the more sophisticated
applications of belt technology in common practice today. In the
technology of the current day, many applications of belts require
much more sophisticated qualities and utilities, and in particular,
for such special applications as in electrostatographic imaging
apparatus and processes using a flexible photoreceptor belt or a
flexible electroreceptor belt, in combination with either a
intermediate transfer member, or image transport devices, or fusing
member, or transfix devices in the flexible belt form. It is ideal
to provide a seamless flexible belt whereby there is no seam in the
belt which mechanically interferes with any operation that the belt
performs or any operation that may be performed on the belt. While
this is ideal, the manufacture of seamless belts requires rather
sophisticated manufacturing processes which are expensive and are
particularly more sophisticated, difficult and much more expensive
for the larger belts. As a result, various attempts have been made
to provide seamed belts which can be used in these processes.
Previous attempts to manufacture seamed belts have largely relied
on belts where the two opposite ends of a rectangularly cut sheet
of the belt material have been lapped or overlapped and
ultrasonically welded to form the seam, or have butted against one
another and then fastened mechanically by heat or other means of
adhesion such as by the use of an adhesive.
[0004] The belts formed according to the typical butting technique
while satisfactory for many purposes are limited in bonding,
strength and flexibility because of the limited contact area formed
by merely butting the two ends of the belt material. Furthermore,
belts formed according to the lapping or overlapping and ultrasonic
welding technique have excessive seam thickness which provides a
bump or other discontinuity in the belt surface leading to a
significant height differential over the adjacent portions of the
belt, of 0.003 inches or more depending on the belt thickness,
which leads to performance failure in many applications. In
electrostatographic imaging process utilizing an overlapping
ultrasonically welded seamed belt, two most severe problems that
the imaging belt has encountered during the imaging and cleaning
processes are, for example, one involves cleaning the imaging belt
of residual toner after transfer of the toner image due to the
excess in seam height, while the other is the dynamic fatigue seam
cracking as a result of large induced bending stress when seam
bends and flexes over various belt support rollers of the belt
module caused by the increase in seam thickness. Therefore, with a
bump, crack or other discontinuity in the seam area of the belt,
the cleaning function of a blade is affected which allows toner to
pass under the blade and not be effectively cleaned off from the
imaging belt surface, since intimate contact between the imaging
belt and the cleaning blade is not maintained. A crack in the seam
has also been seen to become a site that collects and traps toners
which are eventually spewed out to the imaging zones of the imaging
belt surface causing copy printout defects. Furthermore, seams
having differential heights may, when subjected to repeated
striking by cleaning blades, cause the untransferred, residual
toner to be trapped in the irregular surface morphology of the
seam. As a consequence, an electrostatographic imaging belt which
is repeatedly subjected to this striking action, during imaging and
cleaning processes, tends to delaminate at the seam when the seam
is subjected to constant battering by the cleaning blade. Since the
severe mechanical interaction between the cleaning blade and the
seam also causes blade wear problem, the result often observed is
that both the cleaning life of the blade and the overall life of
the imaging belt under a service environment can be greatly
diminished as well as degrading the copy print-out quality. In
addition, the mechanical striking of the cleaning blade over the
excessive seam height has also been found to give rise to
vibrational disturbance in imaging development zone which affects
the toner image formation on the belt and degrades resolution and
transfer of the toner image to a receiving copy sheet. Moreover,
the discontinuity or seam bump in such a belt may result in
inaccurate image registration during development, inaccurate belt
tracking and overall deterioration of motion quality, as a result
of the translating vibrations. This is particularly prevalent in
those applications requiring the application of multiple color
layers of liquid or dry developer on an imaging belt surface to
form the colored toner images, which are subsequently transferred
to the final receiving copy sheet. Another disadvantage is that the
presence of the discontinuity in belt thickness at the seam area
has also been seen to reduce the flex life and continuity of
strength of the belt during dynamic fatigue belt cycling when belt
bends over various belt support module rollers.
[0005] Therefore, for all practical application purposes and
prolonging a belt's service life, it is desired to provide a seam
height differential between the seam and the unseamed adjacent
portions less than 0.001 inch or not to add more than 20 percent of
the unseamed parent material thickening.
[0006] It has been shown that an endless seamed belt, having very
small seam height differential, can be formed with patterned
interlocked ends, the pattern of the ends being formed by using a
laser or a die to cut the pattern and the patterned cut ends being
brought together to interlock to form a seam. In experiments the
patterned seams were first generated using a CO.sub.2 laser
programmed to make various patterned node sizes and spacings.
Although the laser was an excellent tool for providing the cut
pattern geometries and conditions, however it was a costly and
timely process and an inappropriate process for manufacturing seams
for large volumes of belt production implementation because the
focused CO.sub.2 laser has a fine beam size that has to make
hundreds of bends, twists, and turns in order to produce the small
node pattern cuts as the laser traverses across the whole wide of
the imaging web. Since the CO.sub.2 laser is a heat laser, the
generated heat that melts and cuts the imaging web material has
been found to cause heat induced material shrinkage of the cut
patterns. Alternatively, a 1 inch length punch press die was
designed to cut small belt seam samples for testing purposes. The
die cut is much faster and cleaner than the CO.sub.2 laser cut and
the die cut was determined to be the preferred method to be used in
the patterned seam belt manufacturing process; unfortunately, the
mechanical force employed for cutting the imaging web is also seen
to cause the material to develop permanent deformation. To yield
the desirable seam cut pattern, the size of approximately 0.5mm and
the spacings of approximately 25 microns for the nodes, it requires
very accurate cutting by a die. Such a requirement has been found
to be impossible for a die to maintain and provide the demanding
tolerances for the width of an operational belt seam.
[0007] In essence, both the CO.sub.2 laser and mechanical die
cutting methodologies have their respective undesirable shortcoming
of causing imaging material dimensional change at the vicinity of
the cut patterns, which have a precise shape tolerance to yield the
perfect seam mating result. Therefore, there is an urgent need at
present to develop a mechanically robust thin seam design and its
preparation method for imaging belts application.
[0008] The following disclosures may be relevant to various aspects
of the present invention:
[0009] U.S. Pat. No. 1,303,687
[0010] Inventor: C. Leffler
[0011] Issued: May 13, 1919
[0012] U.S. Pat. No. 2,461,859
[0013] Inventor: A. J. Vasselli
[0014] Issued: Feb. 15, 1949
[0015] U.S. Pat. No. 2,792,318
[0016] Inventor: H. P. Welch
[0017] Issued: May 14, 1957
[0018] U.S. Pat. No. 4,878,985
[0019] Inventor: Thomsen et al.
[0020] Issued: Nov. 7, 1989
[0021] U.S. Pat. No. 5,286,586
[0022] Inventor: Foley et al.
[0023] Issued: Feb. 15, 1994
[0024] U.S. Pat. No. 4,624,126
[0025] Inventor: Avila et al.
[0026] Issued: Nov. 25, 1986
[0027] U.S. Pat. No. 5,688,355
[0028] Inventor: Yu
[0029] Issued: Nov. 18, 1997
[0030] Some relevant portions of the foregoing disclosures may be
briefly summarized as follows:
[0031] U.S. Pat. No. 1,303,687 teaches forming a container from a
body blank with the ends dovetailed together and a covering sheet
which extends beyond the end of the body and has its extending
portion secured down, overlapping the dovetail joint to secure and
finish the container. In forming the container, the body blank is
wrapped around a forming mandrel of the desired shape and the two
dovetail ends are interlocked. At the same time the extending ends
of the covering sheet, which are provided with adhesive, are stuck
down overlapping the joint.
[0032] U.S. Pat. No. 2,461,859 teaches an endless flexible belt
with a patterned dovetail joint. A single die cut may cut both ends
of the patterned dovetail joint at the same time. The ends of the
belt are cut to form a male and female end with a plurality of
spaced dovetailed tabs, the female end fitting into the male end
and the dovetailed tabs interlocking with each other. An adhesive
may be used at the belt joint.
[0033] U.S. Pat. No. 2,792,318 discloses forming splice joints in
fibrous material, each joint being cut so that an interlocking
tongue and groove pattern is formed. The tongues and grooves may be
different shapes. In the finished product, the joints are oriented
at a diagonal with respect to the sides. A coating material may be
used to maintain the interfitted tongues and grooves, however, it
is the interlocking connection of the tongues and grooves that
provides the tensile strength of the joint.
[0034] U.S. Pat. Nos. 4,878,985 and 5,286,586 disclose fabricating
thin flexible endless belts used in electrophotographic printing
systems. The patents teach overlapping the ends of the belt and
welding the ends together to form an endless belt.
[0035] U.S. Pat. No. 4,624,126 teaches a hydraulic press with a
cylinder arrangement for equalizing forces in the event of unequal
loading of the press.
[0036] U.S. Pat. No. 5,688,355 discloses fabricating a flexible
belt by removing some of the layers on the belt ends by ablation
with a masked excimer laser beam. The ends are overlapped to form a
substantially thin flat surface and fused together to form the
endless belt.
[0037] U.S. patent application Ser. No. 08/721,418 entitled
"Process and Apparatus for Producing an endless Seamed Belt" by
Schlueter, Jr. et al., filed Sep. 26, 1996 and assigned to the same
assignee as the present invention, teaches producing an endless
flexible belt using a punch and die. The punch and die have
patterned edges in the form of a puzzle cut pattern with extremely
small nodes and kerfs. The cutting tolerances of the patterned
edges make it necessary to fix the punch with respect to the die so
that there is no misalignment of the punch and die between cutting
operations.
[0038] All of the above references are herein incorporated by
reference.
SUMMARY OF THE INVENTION
[0039] To overcome the above shortfalls and provide a mechanically
robust thin seam design for flexible belt application, one aspect
of the invention is drawn to a method for producing an endless
flexible seamed belt from belt material stock including positioning
a template above the belt material stock and applying a cutting
force to the template to form a first patterned end and a second
patterned end on the belt stock material. The cutting force is
removed resulting the first and second patterned ends of the belt
are cut in a puzzle cut pattern with mutually mating elements which
fit together to form a seam when joined mechanically to enable the
endless flexible seamed belt to essentially function as an endless
belt having a substantially uniform thickness.
[0040] Another aspect of the invention is drawn to an apparatus for
producing an endless flexible seamed belt from belt material stock
including a template with a puzzle cut pattern formed thereon
positioned above the belt material stock and a cutting force
applied to the template to form a first patterned end and a second
patterned end on the belt stock material, wherein the first and
second patterned ends of the belt are cut in a puzzle cut pattern
with mutually mating elements which fit together to form a seam.
When the ends are joined mechanically a flexible seamed belt which
essentially functions as an endless belt having a substantially
uniform thickness is formed.
[0041] Yet another aspect of the invention is drawn to an endless
flexible seamed belt made by an apparatus including a template with
a puzzle cut pattern formed thereon positioned above the belt
material stock and a cutting force applied to the template to form
a first patterned end and a second patterned end on the belt stock
material. The first and second patterned ends of the belt are cut
in a puzzle cut pattern with mutually mating elements which fit
together to form a seam when joined mechanically to enable the
flexible seamed belt to essentially function as an endless belt
having a substantially uniform thickness.
[0042] In a manufacturing mode, it is desirable to have a fast and
accurate method of forming the puzzle cut seam design. Using a
template having the desired puzzle-cut pattern in combination with
an excimer laser for cutting the flexible belt material and
creating the pattern is much quicker and cleaner without the heat
induced material deformation problem as that seen associated with
using a CO.sub.2 laser to form the puzzle cut seam. Alternatively,
a template in the form of a punch and die is also a quick and clean
way to cut the flexible belt material. Employing the excimer laser
cutting and punch and die cutting are cleaner than the laser cut
due to the fact that the CO.sub.2 laser melts the belt material,
which is a particular problem in a multi-layered belt. Having a
clean and low profile puzzle cut seam pattern is very important
when the belt is used in an electrophotographic machine environment
due to the stringent requirement of very small distances existing
between the electrophotographic process subsystem elements and the
belt surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0043] Other features of the present invention will become apparent
as the following description proceeds and upon reference to the
drawings, in which:
[0044] FIG. 1 is an isometric representation of the flexible puzzle
cut seamed belt providing a mechanically invisible and
substantially equivalent seam in performance to that of a seamless
belt.
[0045] FIG. 2 is an enlarged view of a puzzle cut pattern used on
both joining ends of the belt material to provide interlocking
elements having a post portion 14 and a larger head portion 16.
[0046] FIG. 3 is illustrative of an alternative configuration
wherein male 18, 19 and female 21, 23 interlocking portions having
curved mating elements are used in the two ends of the belt
material which are joined.
[0047] FIG. 4 is a further alternative embodiment wherein the
interlocking elements 30, 32 form a dovetail pattern having curved
mating elements.
[0048] FIG. 5 is an additional alternative embodiment wherein the
interlocking relationship between the puzzle cut pattern on both
ends is formed from a plurality of finger joints 22, 26.
[0049] FIG. 6 is a greatly exaggerated in scale representation of
the seam type geometry, a very narrow kerf 20, that will be bonded
by heat and pressure alone.
[0050] FIG. 7 is a greatly exaggerated representation of the belt
seam 11 with the kerf 20 filled with belt compatible material
represented by cross hatching.
[0051] FIG. 8 is a schematic representation of cutting a
rectangular slot at an end of an electrophotographic imaging member
web with an excimer laser using a mask template.
[0052] FIG. 9 is a mask template having the desired puzzle cut
pattern for the excimer laser cutting use.
[0053] FIG. 10 is a front view of the die press used to form the
puzzle cut belt.
[0054] FIG. 11 is an exploded view of the cutting elements in the
die press of FIG. 10.
[0055] While the present invention will be described in connection
with a preferred embodiment thereof, it will be understood that it
is not intended to limit the invention to that specific embodiment.
On the contrary, it is intended to cover all alternatives,
modifications, and equivalents as may be included within the spirit
and scope of the invention as defined by the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
[0056] With continued reference to the figures and additional
reference to the following description the invention will be
described in greater detail. The seam formed according to the
present invention is one of enhanced strength, flexibility and
mechanical life which is held together by the geometric
relationship between the ends of the belt material, which are
fastened together by a puzzle cut, meaning that the two ends
interlock with one another in the manner of an ordinary puzzle and
wherein the seam has voids or a kerf 20 between the surfaces of
mutually mating elements, the opposite surfaces of the puzzle cut
pattern being joined together to enable the seamed flexible belt to
essentially function as an endless belt. The joining of the
opposite surfaces of the mutually mating elements forming the seam
may be either a physical joining, chemical joining or some
combination of physical and chemical joining. The opposite surfaces
of the puzzle cut pattern may alternatively be bound with an
adhesive which is physically and chemically compatible with the
belt material. Typically, this joining provides a bonding between
the opposite surfaces of the mutual mating elements which provides
an improved seam quality and smoothness with substantially no
thickness differential between the seam and the adjacent portions
of the belt thereby providing enhanced imaging, registration and
control as discussed above. In this regard, it should be noted that
the lower the differential in height, the faster that the belt may
travel. In any case, the opposite surfaces of the puzzle cut
pattern being joined together are bound with sufficient physical
integrity to enable the seamed flexible belt to essentially
function as an endless belt. The two ends of the seamed belt may be
joined by heating such as by welding, including ultrasonic welding,
arc welding and impulse welding, wherein top and bottom elements
similar to those that are used to seal plastic bags have two arms
which apply pressure and then the elements are heated. In the case
of thermoplastic belt materials the thermoplastic nodes may be
deformed by heating and may flow into the voids to form or link
together and physically form the bond. As illustrated in FIG. 6 a
very narrow kerf between thermoplastic ends of the belt may be
filled by the mere application of heat and pressure. This is like
welding the two nodes together. This technique of course is not
applicable to thermoset materials.
[0057] Alternatively the two ends of the belt having the puzzle cut
pattern at each end may be joined by a chemical reaction. This
happens in the instance where the belt material is a thermoplastic
and upon heating the thermoplastic at least softens, if not melts,
and flows to fill the voids in the seam.
[0058] Another alternative is to apply an adhesive to the voids
between the mutually mating elements, and in particular, to the
opposite surfaces of the puzzle cut pattern. With the use of an
adhesive a much wider kerf may be used than the very narrow kerf
that may be used for bonding by heat and pressure only
thermoplastic materials. This also permits the adhesive to wick
into the void or kerf areas. In this regard, the viscosity of the
adhesive is important since it's performance depends on it's
ability to wick into the voids or the kerf 20 between adjacent cut
pieces of the pattern. Accordingly, a relatively high viscosity
adhesive will not perform as satisfactorily as a low viscosity
adhesive. In addition, the surface energy of the adhesive must be
compatible with the material from which the belt is fabricated so
that it adequately wets and spreads in the belt seam. As previously
described good adhesion is required to enable the performance
requirements previously discussed with regard to comparing it to
the original material. If the belt is made of a thermoplastic or
thermoset material, it is quite convenient to use thermoplastic or
thermoset adhesives which melt and flow at a temperature below that
of the belt material but do not soften enough or flow during the
belt's operation. The kerf 20, the distance between adjacent
surfaces of the mutually mating elements of the belt ends can be
built into the belt ends by way of a mechanical die or it can be
built into by way of cutting with a laser pattern. If the belt
material is a thermoplastic, a thermoplastic or thermoset or
otherwise crosslinked adhesive may also be used and indeed may be
based on the same material that the belt is fabricated from.
However, if the belt material is thermosetting then a thermoplastic
or thermoset adhesive may be used to fill the voids between the
opposite surfaces of the puzzle cut pattern. Typically, a hot melt
adhesive may be used, which is one that is solid at room
temperature, however, when heated will flow. Typical thermoplastic
hot melt adhesives include polyamides, urethanes, polyesters.
Typical thermosetting materials include epoxies, polyimides,
cyanoacrylates and urethanes. Following bonding, whether it be
physical, chemical or by way of adhesive or any combination of the
above, although it may not be necessary, it may be desirable to
apply pressure to flatten the seam to make it as uniform as
possible and control any thickness differential.
[0059] Referring to FIG. 1, it should be noted that the mechanical
interlocking relationship of the seam 11 is present in a two
dimensional plane when the belt 10 is on a flat surface, whether it
be horizontal or vertical. While the seam is illustrated in FIG. 1
as being perpendicular to the two parallel sides of the belt it
will be understood that it may be angled or slanted with respect to
the parallel sides. This enables any noise generated in the system
to be distributed more uniformly and the forces placed on each
mating element or node to be reduced.
[0060] The endless flexible seamed belt may be made of any suitable
material. Any suitable belt material may be employed. Typical
materials include, photoreceptor materials which may be
multilayered such as those described in U.S. Pat. No. 4,265,990, as
well as a variety of thermoplastic and thermosetting belt
materials. Typical materials include polyesters, polyurethanes,
polyimides, polyvinyl chloride, polyolefins such as polyethylene
and polypropylene and polyamides such as nylon, polycarbonates,
acrylics. In addition, elastomeric materials such as silicones,
fluorocarbons such as Vitons E. I. DuPont.TM., EPDM and nitrites
etc. For certain purposes, metallic; cloth and even paper may be
used. The belt material is selected to have the appropriate
physical characteristics for specific utilities such as tensile
strength, Young's modulus, typically 1.times.103 to 1.times.106,
electroconductivity, typically 10.sup.8 to 10.sup.11 ohm cm volume
resistivity, thermal conductivity, stability, flex strength and in
certain applications, such as transfix, being capable of being
subjected to high temperatures. Other important characteristics of
the belt material include surface energy desired low for good toner
release, for example, gloss, dielectric constant and strength.
[0061] The puzzle cut pattern has been formed according to
conventional shaping technique, such as by die cutting or laser
cutting with commercially available lasers, such as a CO.sub.2
laser or excimer laser. However, the use of excimer laser puzzle
pattern cutting is preferred because it generates a beam of
sufficient width and intensity that within an acceptable time will
provide the desired cut. Following cutting by the laser beam it can
be deburred and cleaned by air, ultrasonics or brushing if
necessary. The puzzle cut pattern may be formed on each of the ends
by a male and female punch with the belt material in between which
punches out the shape. Alternatively, it could be a pattern on a
wheel which rolls over the material.
[0062] It has been found that a CO.sub.2 laser utilizing a focused
heat beam is unsuitable for the precise reshaping requirements of
this invention. Although a CO2 laser beam can be small and
localized, it melts or burns the material upon which is focused.
Because the wavelength of a CO.sub.2 laser is about 10.6
micrometers, which is in the far infrared region of the spectrum,
the CO.sub.2 laser beam apparently functions much like a heat
radiation beam that melts and burns away the material to be
removed. This is evidenced by the appearance of smoke rising from
the photoreceptor during CO.sub.2 laser beam treatment. Moreover,
the molten mass accumulation forms beads of surface protruberance
upon cooling to room ambient. Localized heating caused by a
CO.sub.2 laser also tends to distort or warp photoreceptor
substrates. In addition, when heat-type laser beams are utilized,
multiple passes are often required to control the removal of
material from both marginal end regions of the imaging member.
These multiple passes require complex equipment and prolong the
time required for material removal. Attempts to use of a YAG laser
having a wavelength of about 1.06 micrometers to remove material
from a photoreceptor merely heats the photoreceptor and discolors
the charge generator layer. Lasers that ablate photoreceptor layers
by heating also causes undesirable ripples to form in the
photoreceptor. These ripples trap toner particles which, in turn,
tend to agglomerate and form smears on the photoreceptor surface or
form particulate deposits in background areas of final imaged
copies. In addition, the ripples trap air which is heated during
impulse heat-fuse welding process to the point where expansion of
the air causes bubbles that weaken the final welded photoreceptor
seam. The presence of small bubbles (that heat up and expand during
welding) can produce a pronounced weakness in the welded seam,
particularly when the overlap of the sheet ends is relatively
small.
[0063] The puzzle cut ends of the present invention are formed by
exposing a belt to a masked excimer laser. Excimer laser has a
characteristic rectangular beam profile emission of about 3.0
cm.times.1.5 cm and exhibits an uniform top hat like energy
distribution. Excimer lasers take their name from the excited state
dimmers from which lasing occurs. Currently, the most important
excimer lasers are the rate-gas-halides such as ArF, KrF, XeCI, and
XeF which produce intense UV radiation of distinctive wavelengths
from 193 nm (ArF), 248 nm (KrF), 308 nm (XeCI), to 351 nm (XeF).
Since the excimer molecules have short life-times that exist for
only a few nanoseconds, they require a fast excitation process. The
excimer lasers, however, have no or only weakly bound ground states
and they imply high gain and high energy capabilities. Thus, in
comparison to solid state lasers, excimer lasers are easier to
operate. In commercial excimer laser technology, the excitation
process is executed by a fast high pressure electrical discharge
applied to a gas mixture which contains small amounts of a halogen
and a rate gas, diluted in helium or neon buffer gas. This results
in generation of short UV laser pulses leaving the discharge cavity
in a beam of fairly low divergence and exhibiting a characteristic
rectangular profile of approximately 3 cm.times.1.5 cm which has a
cross section of about 4.5 cm.sup.2. No heat is generated by an
excimer laser and it does not burn the substrate. Therefore, an
excimer laser does not heat or otherwise adversely affect areas
adjacent the laser path. This permits greater control during
removal of material. Upon direct exposure, excimer lasers convert
the photoreceptor materials to a gas by breaking down the molecular
chains of polymeric components of the photoreceptor into smaller
fragments. The excimer laser beam is pulsed during operation.
Satisfactory results may be achieved when the pulse frequency is
between about 50 Hz and about 500 Hz. Preferred pulse frequency
ranges from about 100 Hz to about 300 Hz. The frequency of the
pulse selected for any given set of sheet materials depends upon
the speed of traverse, distance and power of the laser beam. For
example, a slower laser beam traverse permits a lower pulse
frequency to achieve the desired removal of belt material to form
the trough. Typical traverse rates for a flexible
electrophotographic imaging member sheet are between about 30 mm
per second and about 0.5 mm per second.
[0064] FIG. 8, represents a moment frozen in time of a first
marginal end region 50 of a multi-layered, flexible
electrophotographic imaging member 52 being traversed, in a
direction from right to left, by a masked ultraviolet excimer laser
beam 46, which is incident on second major exterior surface 56
along a first edge surface 58 of imaging member 52. Original
excimer laser beam 40 is directed through a metal masking plate 42
having a rectangular opening 44 which removes the non uniform low
energy edges from beam 40 thereby providing an emerging masked
ultraviolet excimer laser beam 46 of even energy distribution for
precise coating layer material displacement when directed toward
second major exterior surface 56. Unlike infrared lasers, such as
CO.sub.2 and YAG lasers which produce intense thermal heating
effects, exposure of imaging member 52 to high energy short
wavelength UV radiation from masked ultraviolet excimer laser beam
46 can produce a number of important effects including: energy
absorption by long chain polymer molecules to elevate these
molecules to an electronic excitation state in the coating layers;
chain scission of the polymer molecules into small molecular
fragments; ablation removal of the molecular fragments away from
the surface as a puff of gas, creating a total cutting through of
the material layers adjacent first edge surface 58 of imaging
member 52. In this manner, each masked excimer laser pulse
displaces a thin layer of material 51 from imaging member 52 to
precisely remove imaging member material in full accordance with
the laser beam exposure profile of the mask to yield a
predetermined cutting pattern through the imaging member. The laser
beam 40 is pulsed during the imaging member shaping operation. The
frequency of the laser pulses is adjustable from only about a few
pulses per second to about 300 Hz. Since each laser pulse occurs on
an extremely brief time scale and provides only the energy for
molecular excitation of the polymer coating, no heat is generated
in the process to cause dimensional distortion or material melting
to the imaging member 52. The masked ultraviolet excimer laser beam
46 traverses a portion of the imaging member web to create a
cut-through 55. It is also important that original excimer laser
beam 40 is masked to achieve sharp corners at the top and bottom of
cut 55 formed during excimer laser ablation.
[0065] Any suitable masking plate material may be utilized. A
typical masking plate 42 comprises a metal. Any suitable metal may
be utilized. Typical metals include, for example, stainless steel,
carbon steel, nickel, and the like. Further, with masked excimer
laser beam 46 utilized in the process of this invention, no heat is
generated and the components of electrophotographic imaging member
52 are not degraded by heating or burning. This also avoids heat
distortion of areas adjacent the path of laser beam 46 and achieves
greater control of the shape of the cut-through 55 created by
masked ultraviolet excimer laser beam 46. Thus, masked ultraviolet
excimer laser beam 46 utilized in this invention removes coating
layers from marginal end region 50 of electrophotographic imaging
member 52 with greater precision to produce the desired cut-through
55 on electrophotographic imaging member 52.
[0066] FIG. 9 shows the mask template 42 with a puzzle cut pattern
aperture 44 formed therein to be employed for the imaging member
cutting application described in the preceding FIG. 8. In the
embodiment, it is shown that the template has a template aperture
in the form of a puzzle cut pattern; since the excimer laser
emission has an uniform radiation energy area many times wider than
the breadth of the puzzle cut pattern aperture in the mask
template, the puzzle cut pattern may be easily and quickly
generated as the excimer laser is transporting in a straight
direction over the mask template which was positioned directly
above and perpendicular to the two edges of an imaging member web.
With this cutting strategy employed for a long imaging member
webstock in a continuous production process, the pattern created at
the opposite cut ends of a resulting imaging member sheet shall
have a perfect matching male and female pairs for excellent
mechanical interlocking. However, if desired this mask template may
be split into the left half and the right half mask templates for
individual creation of left and right ends puzzle cutting in an
imaging member sheet.
[0067] The mask template of FIG. 9 can also be used to form only
one end at a time or be of any desirable pattern to form
interlocking ends, depending upon the configuration of the
template. When the pulsing excimer laser 40 traverses over the mask
template 42 and across the full width of the belt, a matching pair
of puzzle cut ends like that of the template aperture 44 is created
without the introduction of heat.
[0068] As may be observed from the drawings, the puzzle cut pattern
may take virtually any form, including that of nodes such as
identical post or neck 14 and head or node 16 patterns of male 13
and female 15 interlocking portions as illustrated in FIG. 2, or a
more mushroom like shaped pattern having male portions 18 and 19
and female portions 21 and 23 as illustrated in FIG. 3 as well as a
dovetail pattern as illustrated in FIG. 4. The puzzle cut pattern
illustrated in FIG. 5 has a plurality of male fingers 22 with
interlocking teeth 24 and plurality of female fingers 26 which have
recesses 28 to interlock with the teeth 24 when assembled. It is
important that the interlocking elements all have curved mating
elements to reduce the stress concentration between the
interlocking elements and permit them to separate when traveling
around curved members such as the rolls 12 of FIG. 1. It has been
found that with curved mating elements that the stress
concentration is lower than with square corners where rather than
the stress being uniformly distributed it is concentrated leading
to possible failure.
[0069] It has been found that with curved mating elements that the
stress concentration is lower than with square corners where rather
than the stress being uniformly distributed it is concentrated
leading to possible failure. The mechanical bonding, strength and
flexibility of the bond should be capable of supporting a belt
cycling of at least 500,000 cycles and the height differential
between the seamed portion and the unseamed portion on each side of
the seam about 0.001 inch and the seam have a tensile strength of
at least 80% and preferably 90% of the parent belt material
strength.
[0070] The following is a discussion of the interrelationship among
the various belt and material parameters involved in the mechanical
integrity of the seam. The mechanical integrity of the seam was
examined and analyzed for a number of configurations and in
particular for the preferred configuration which involves nodes
forming parts of a circle and interconnecting via a neck on the
opposite side. To determine the deflection under loading
conditions, each such node is treated as a beam fixed at the
narrowest part of the neck joining the node to the base and the
deflection of each tooth (node and neck) is calculated in terms of
the orientation of the load relative to the beam. To assure that
the seam will not come apart under load, it is imposed that the
maximum deflection of each tooth, when the load, under worse
conditions, is normal to the beam, would not exceed the thickness
of the belt itself. Clearly, if the deflection of the tooth is in
excess of the thickness of the belt then the seam will come apart.
Under the above brief analysis, a master relationship connecting a
material parameter M typical of the configuration with a geometric
parameter G such that the belt will not come apart under loading. 1
M = 1 - G ( 1 + 4 - 1 G 2 ) 3 ( 1 )
[0071] In this relationship M is a dimensionless quantity given by
2 M = 4 NR 3 Et 4 and G represents the ratio ( 2 ) G = 2 R w ( 3
)
[0072] where N is the total load per unit width (i.e. lbs/in.)
acting on the belt, E is the modulus of elasticity of the belt
material t, the thickness of the belt, R the radius of the circular
node forming the seam, and w is the wave length of one whole period
between two adjacent nodes. Equation (1) is a one-to-one
relationship between the material parameter M and the geometric
parameter G. Thus, given one of them we can find the other
parameter. Furthermore, because of the dimensionless nature of
these two parameters, a multitude of configurations are embodied in
each pair of values satisfying equation (1), by virtue of the fact
that there is an infinite number of combinations of the variables
involved in that particular pair of values of M and G. Inspection
of the geometry of the node shows that the structure is
characterized by two main features: the shoulder, or that portion
where there is interference between adjacent teeth, which supports
the seam, and the neck of each tooth which represents its strength
under loading. The size of the shoulder should be sufficient to
insure mechanical integrity of the seam without making the neck too
small as to weaken its strength. Table 1 below lists the various
parameters for the identified belt characteristics. While all
samples will function as noted above, a value of G of 0.6 is a good
compromise. Many of the samples of course are impractical to
implement relative to factors such as manufacturing ease, costs,
stress tolerance, etc. Equation (3) shows that G can only vary
between 1/2 and 1, the first value refers to the case when the
shoulder is zero, and the second value pertains to the case when
the neck of the tooth is zero and the node has no strength. Once
either M or G is known the entire configuration becomes determinate
with the help of the above equations and other standard geometric
relationships. Measurements on actual belts have generally
confirmed the above analysis. To illustrate the solution
methodology, suppose a belt material of Young's modulus
E=5.times.105 psi and thickness t=0.004" is subjected to a tension
N=2.0 lb./in. of belt width. H is the perpendicular height between
centers of one node or one side of the seam and a node on the other
side of the seam. The solution possibilities are given in Table 1
below such that the seam will not come apart. If a value G=0.6 is
chosen as a compromise between seam integrity and node strength, we
find
1 Node Diameter D = 0.448 mm Period w = 0.747 mm Neck Width g =
0.299 mm Node Height H = 0.69696 G 1/M D W g H .5000 2.000 1.0160
2.0320 1.0160 1.0160 .5100 5.5296 .7239 1.4194 .6955 .8665 .5200
7.7482 .6469 1.2440 .5971 .8246 .5300 9.7913 .5984 1.1290 .5306
.7968 .5400 11.7592 .5629 1.0424 .4795 .7755 .5500 13.6903 .5351
.9729 .4378 .7580 .5600 15.6054 .5122 .9147 .4025 .7429 .5700
17.5179 .4929 .8647 .3718 .7295 .5800 19.4383 .4761 .8208 .3448
.7174 .5900 21.3751 .4612 .7818 .3205 .7061 .6000 23.3363 .4479
.7466 .2986 .6956 .6100 25.3292 .4359 .7146 .2787 .6856 .6200
27.3614 .4248 .6852 .2604 .6760 .6300 29.4406 .4146 .6580 .2435
.6668 .6400 31.5747 .4050 .6328 .2278 .6578 .6500 33.7722 .3960
.6093 .2132 .6491 .6600 36.0424 .3875 .5872 .1996 .6405 .6700
38.3950 .3794 .5663 .1869 .6320 .6800 40.8411 .3717 .5466 .1749
.6236 .6900 43.3927 .3643 .5279 .1637 .6153 .7000 46.0632 .3571
.5101 .1530 .6070 .7200 51.8235 .3433 .4769 .1335 .5904 .7300
54.9497 .3367 .4612 .1245 .5820 .7400 58.2687 .3302 .4462 .1160
.5736 .7500 61.8060 .3238 .4317 .1079 .5651 .7600 65.5913 .3174
.4176 .1002 .5565 .7700 69.6594 .3111 .4040 .0929 .5477 .7800
74.0510 .3048 .3908 .0860 .5388 .7900 78.8149 .2986 .3779 .0794
.5297 .8000 84.0090 .2923 .3653 .0731 .5204 .8100 89.7035 .2860
.3530 .0671 .5109 .8200 95.9840 .2796 .3410 .0614 .5012 .8300
102.9563 .2731 .3291 .0559 .4911 .8400 110.7522 .2666 .3173 .0508
.4807 .8500 119.5388 .2599 .3057 .0459 .4700 .8600 129.5306 .2530
.2942 .0412 .4588 .8700 141.0081 .2459 .2827 .0367 .4472 .8800
154.3451 .2386 .2712 .0325 .4350 .8900 170.0512 .2311 .2596 .0286
.4222 .9000 188.8397 .2231 .2479 .0248 .4086 .9100 211.7410 .2148
.2360 .0212 .3942 .9200 240.2999 .2059 .2238 .0179 .3787 .9300
276.9445 .1964 .2112 .0148 .3620 .9400 325.7211 .1860 .1979 .0119
.3436 .9500 393.9129 .1746 .1838 .0092 .3231 .9600 496.0860 .1617
.1684 .0067 .2997 .9700 666.2290 .1466 .1511 .0045 .2722 .9800
1006.3020 .1277 .1303 .0026 .2376 .9900 2026.1140 .1012 .1022 .0010
.1885
[0073] To minimize any time out or nonfunctional area of the belt
it is desirable to have the seam width be as narrow as possible.
Further, this enables the seam to be indexed so that it does not
participate in belt functionality such as the formation and
transfer of a toner or developer image. Typically, the seam is from
about 1 mm to about 3 mm wide.
[0074] With reference to the embodiment illustrated in FIG. 2, the
seam may be typically of the order of one inch wide on a belt which
is 16 to 18 inches long depending on roll diameter, material
modulus or other parameters and the post and head pattern may be
formed from a male/female punch cut with each end being cut
separately and subsequently being joined to form the seam with a
roller similar to that used as a wall paper seamer rolled over the
seam by hand to complete the interlocking nature of the puzzle cut
pattern.
[0075] The two ends of the belt material are joined by physically
placing them together in interlocking relationship. This may
require the application of pressure to properly seat or mate the
interlocking elements. The adhesive material may be the same or it
may be different from the material from which the belt was
fabricated and may be selected from those materials previously
discussed. Typically, it is a heat sensitive thermoplastic or
thermoset material. It may be either chemically, and/or physically
bound to the belt material. The chemical and/or physical bond
between the adhesive and the belt material may also be formed by
the application of heat and/or pressure after the adhesive has been
applied In a particular application impulse welding may be applied
wherein heat and pressure are simultaneously applied to at least
soften the belt material and the compatible adhesive material 17
(see FIG. 7) so that it fills the kerf and forms an adhesive bond
with the belt material. In this regard, it is important that the
heat applied does not exceed that which would both form the seam
and break it by melting it or decomposing it. Other heat sources
include conventional heated rolls, a simple heated iron, ultrasonic
welding or a two roll heated nip providing a combination of heat
and pressure.
[0076] Preferably, the adhesive material applied is of a thickness
to provide a quantity of adhesive to fill the kerf spaces between
the two sides of the puzzle cut seam member. In this regard it
should also be noted that it may be possible to first apply the
heat to, the seam of the belt material and the adhesive and
subsequently apply pressure while it is still in a softened
condition to force the softened adhesive into kerf or the spaces
between the two sides of the puzzle cut seam members. The pressure
applied should be sufficient to fill the kerf and to minimize the
thickness of any bonded joint. While this process clearly provides
a physical bonding between material of the belt seam and the
adhesive material, it may also provide a chemical bond. A typical
example of this would be one wherein the belt material is a
polyimide and the adhesive is a polyimide.
[0077] Following fabrication, the belt may be finished by way of
buffing or sanding and further, may have an overcoating applied,
typically, of a thickness of 0.001 to 0.003 inch in thickness which
can be initially applied to the unseamed belt, the belt seam and
the seamed area filled from the back of the belt to maintain the
uniformity of the functional surface. Preferably, and by far the
most economical matter is to form the belt seam initially and then
apply the desired overcoating.
[0078] The seamed belt according to the present invention may be
fabricated in an environmentally acceptable manner in that no
solvents are required. The adhesive may be applied to the belt in a
suitable manner, such as by being applied from a tubular applicator
by squeezing or pushing or being applied by a spatula. It may be
applied on one or both sides of the kerf or voided area and is
preferably smoothed on it's surface to provide a smooth surface in
the seam area of the belt.
EXAMPLE 1
[0079] Using a die cutter, a one inch wide polyimide material was
mechanically cut to provide a radius of the nodes of about 0.5 mm
and the center to center spacing of about 0.70 mm. The ends of the
strip of the one inch width polyimide material were then
interlocked and rolled with the roller to flatten the seam. A
thermoplastic polyamide web material was placed on the lower jaw of
an impulse welder Vertrod Corp. Model No. 24H/HT1/4. The previously
joined seam was then centered over the webbing material, heat at
approximately 350.degree. F. and light pressure were then applied
to melt the polyamide web material into the seamed area for
approximately 20 seconds. With the seam remaining on the lower jaw
of the impulse welder, both sides of the seam were then masked with
conventional masking tape, a bead of a polyimide adhesive was
squeegeed into the area formed by the masking tape and permitted to
flash to release solvent for about 15 minutes after which the
masking is removed. The impulse welder is once again clamped again
and the seam receives two cycles of 350.degree. F. heat for 35
seconds. The seam remained in the impulse welder for 30 seconds
before it was removed and postcured at 400.degree. F. for 2 hours
and then room temperature dwell for at least 12 hours. Fourteen, 12
inch long belts were tested in the flex tester and all had flexing
cycles exceeding 750,000 with 9 samples exceeding one million
cycles. Of the nine belts, which flexed for over a million cycles,
the test was discontinued without any of the belts failing. The
samples were tested in a flex tester using two pounds in loading,
17 inch per second process speed around the 25 mm drum rollers.
[0080] Turning now to FIG. 10, which shows a front view of the die
press assembly used to cut the patterned ends of the belt. Die 102
is supported by die retainer plate 106. Punch 104 is supported over
the die 102 by punch retainer plate 108 and punch assembly retainer
120. A stripper 114 surrounds the punch 104, there being a very
small clearance between the punch and stripper. Stripper 114 has a
puzzle cut pattern which is complementary with the punch puzzle cut
pattern so that the stripper assists in locating the punch with
respect to the die. The stripper is fixed to die 102 so that a
stock gap exists for the belt material 111 to pass between the
stripper and die. The stock gap is formed by shims 140 (see FIG.
11) between the stripper and the die. The stripper 114, die 102 and
die retainer plate 106 are fixed together and remain stationary
during the belt cutting process.
[0081] Timing blocks 112 are mounted to both ends of punch
retaining plate 108 and are located above stripper 114. Timing
blocks 1 12 cooperate to keep the punch assembly level; when the
first timing block hits stripper 114 this causes the punch assembly
to level out and when the other timing block hits the stripper, the
direction of punch assembly is reversed (discussed below).
[0082] Guide posts 116 pass through punch retainer plate 108 and
die retainer 106 and assist in keeping all of the punch and die
members properly aligned. Punch return assembly 118 connects the
punch retainer plate 108 and die retainer 106 and returns the punch
to its ready to cut position once the cutting force is removed.
Punch assembly retainer 120 supports punch retainer plate 108,
punch 104 and timing blocks 112; punch assembly retainer 120, punch
plate 108, timing blocks 112 and punch 104 being fixed with respect
to each other. Punch assembly retainer 120 is a solid piece of
metal and distributes the cutting force along the full length of
punch retaining plate 108.
[0083] At the top center of the punch assembly retainer is force
receiving surface 122. Above force receiving surface 122 is force
generating assembly 124 having a force generating surface 126, a
cylinder travel gap 128 being formed between the two surfaces when
the force generating assembly is in the retracted position The
force generating assembly may be a hydraulic press or any
equivalent press which can generate sufficient force to cut the
belt material. Force generating assembly 124 provides a downward
force with force generating surface 124 contacting force receiving
surface 122 which supplies the cutting force to the punch assembly
until both timing blocks 112 contact stripper 114 (as shown). At
this time the force generating assembly force direction is reversed
and the cutting force removed. Punch assembly 120 moves upward due
to the upward force of spring 121 of punch return assembly 118, the
top of the bolt 119 limiting the upward movement of the punch.
[0084] Force generating assembly 124 is supported independently of
the punch and die members. Force generating assembly horizontal
support 130 and vertical supports 132 are attached to die table
140. Vertical supports 132 have a foot member 134. Die retainer 106
supports all of the punch members and die members and is also
attached to die table 140. As shown, die retainer 106 has cut out
portions 136 on its underside with foot members 132 captured in the
cut out portions. This configuration insures that force generator
assembly horizontal support 140 will remain stationary with respect
to the die when the cutting force is supplied is supplied by force
generating assembly 124.
[0085] Rather than having the punch assembly attached to the force
generating member as is usual for die presses, the punch members
are fixed to the die members by punch return assembly 118. The
punch return assembly 118 shown has a plurality of punch return
assembly bolts 119 and punch return assembly springs 121, which
connect the punch and die assemblies and bias the punch assembly
towards the force generating assembly, away from the die assembly,
when the cutting force is removed. This configuration allows the
punch and die to remain in close proximity and properly aligned
with one another. Any misalignment of the punch and die would
result in catastrophic failure when the next punch force is
applied.
[0086] An exploded view of the punch and die assemblies is shown in
FIG. 11. The cutting assembly 100 is formed of a die 102 and punch
104. The die and punch have complementary surfaces which form the
puzzle cut pattern when the cutting operation is performed. Die 102
has two die cutting ends 160 and 161 and two die cutting edges 162
and 163 and punch 104 has two punch cutting ends 164 and another
end(not shown) and two punch cutting edges 166 and another edge
(not shown) . Die cutting end 160 and punch cutting end 164
interact to form the puzzle cut pattern at the first end of a belt
and die cutting end 161 and the other punch cutting end interact to
form a complementary puzzle cut pattern for the second end of a
belt with die cutting edge 162 and punch cutting edge 166
interacting to form a first side of the belt and die cutting edge
163 and punch cutting edge (not shown) interacting to form a second
side of the belt. There is a very small clearance between punch
cutting edges and the die cutting edges to insure proper cutting
tolerances of belt material 111. A stock gap is formed between
stripper 114 and die 102 surfaces with shims 140 spacing the two
members for the desired stock gap width.
[0087] Stripper 114 holds the cut belt material in place as the
punch returns to its pre-cut position, thus performing its
stripping function. In operation, the die assembly cuts the first
end of belt at the same time it cuts the second end of belt. The
belt material is fed through the stock gap in any known manner, for
example as a mechanized or hand placement process, the length of
the belt being determined by the distance between the first puzzle
cut end and the second puzzle cut end of the punching template.
[0088] The first feature that required development in forming the
extremely accurate punch and die cutting edges was the proper steel
and heat treatment process to maintain less than 0.04% dimensional
change and no warpage when wire cut or ground. After several
experiments, the optimum material and process was D-2 steel, 0.5
inch thick die plates hardened to R/C 57 and drawn three times at
1875 Fahrenheit. After hardening, the plates were cryogenically
treated to -120 Fahrenheit. Then two more draw operations at 920 F.
and 950 F. were performed. A cut relief 104 was incorporated in the
center of the die to relieve stress prior to hardening. The treated
material was then cut using an EDM technique, the punch 102 and die
104 plates being formed separately. Four cutting passes were
required to maintain tolerances so that the very small nodes and
even smaller spacing tolerances required were produced in the
finished punch and die. The last cutting pass was a skimming pass
of 0.0002 inches. The length of the die depends upon the desired
belt width. The belt width can be as much as 60 inches using the
drawing and EDM cutting techniques outlined above.
EXAMPLE 2
[0089] The particular configuration of the puzzle cut with the
rounded puzzle cut pattern will be discussed (see FIG. 7 and 8),
however any desired pattern could be formed with the appropriate
punch and die pattern. The approximate clearance between the punch
and die patterned edges is 0.0002 inches, the punch and stripper
clearance is 0.0001 inches, the clearances being measured on each
side of the punch and die. The node diameter was 0.5 mm and the
kerf dimension was 25 microns. The punch assembly is returned
approximately 0.100 inches above the belt material after the cut is
made. The punch and die cutting edges may be configured so that the
seam is at a slight skew with respect to a 90 degree straight edge
belt, which increases the integrity of the seam. The belt material
used may be any material described above, for example a
photoreceptor or Mylar. The length of the puzzle cut pattern punch
cutting ends is 18 inches and the distance between punch cutting
ends is 3 feet. Using the above shapes, tolerances and materials, a
"seamless", i.e. a belt which essentially performs as a seamless
belt, puzzle cut transfer belt was produced.
[0090] The above cross referenced patent applications together with
the patents cited herein are hereby incorporated by reference in
their entirety in the instant application. It is, therefore,
apparent that there has been provided in accordance with the
present invention, a precision punch and die and a die press for
forming puzzle cut patterned belts that fully satisfies the aims
and advantages hereinbefore set forth. While this invention has
been described in conjunction with a specific embodiment thereof,
it is evident that many alternatives, modifications, and variations
will be apparent to those skilled in the art. Accordingly, it is
intended to embrace all such alternatives, modifications and
variations that fall within the spirit and broad scope of the
appended claims.
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