Flexible molded core shaft

Details Flexible molded core shaft Flexible molded core shaft

1999-10-25

2002-01-22

Browne, Lynne H. (Department: 3629)

Rotary shafts, gudgeons, housings, and flexible couplings for ro

Torque transmitted via flexible element

Nonmetallic element

C264S279100, C464S903000, C464S182000, C464S181000

Reexamination Certificate

active

06340333

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to shaft for use in machines. In particular, the present invention relates to flexible shafts comprised of at least two rigid, tubular, shell-like portions containing, and linked together by a flexible, moldable material.
BACKGROUND OF THE INVENTION
While the present invention has utility in apparatus comprising various mechanical components, it has particular application, and will therefore be described with reference to, electrostatographic printers.
FIG. 1
illustrates an exemplary electrostatographic printer
8
. That printer includes a photoconductive drum
10
that rotates in the direction
11
. The surface of the drum
10
is charged to a substantially uniform potential by a corotron
12
. The charged drum is then exposed to a light image of an original document
15
on an exposure platen
16
by means of an exposure lamp
17
. The original document is moved over the exposure platen such that the full document is exposed to light from the exposure lamp. The light image of the original document discharges the charged surface of the drum so as to create an electrostatic latent image of the original document. A developer
20
then deposits toner on the electrostatic latent image so as to produce a toner image of the images on the original document
15
. The toner image is comprised of charged toner particles that triboelectrically adhere to the electrostatic latent image. The toner image is subsequently transferred at a transfer station
24
onto a substrate
21
, which is fed by a paper tray feeder
22
into intimate transfer contact with the toner image. The transferred toner image is then permanently affixed to the substrate by heat and/or pressure in a fuser
23
. After transfer, residual toner, paper particles, dust, or other debris on the drum
10
is removed by a cleaner
26
in preparation for the next imaging cycle.
While
FIG. 1
provides a simplified description of an exemplary electrostatographic printer, in practice such printers are far more complex. For example, such printers include numerous electrical subsystems, such as digital controllers and power supplies, and mechanical subsystems that rotate the drum, move substrates through the machine, and sort and staple image-bearing substrates together. For example,
FIG. 2
illustrates a simplified view of the paper tray feeder
22
. That feeder includes a tray for holding substrates
30
and an upper frame member
26
that closes over the tray. The upper frame member selectively removes the top substrate from the paper tray and feeds it as described above. To assist removal and feeding, the upper frame member includes two shafts, the shafts
32
and
34
. Those shafts retain gears, rolls, pulleys, and friction surfaces, may include retention or location features such as, snaps, fitting elements or stops, and may contain other features such as bearings, bushings, rollers, journals and
0
-rings. When a gear
36
on the shaft
32
is rotated by an external drive, a friction surface
38
contacts the topmost substrate and advances it toward the shaft
34
. The shaft
34
is rotated by a drive belt
35
connected on a pulley
37
and a pulley
39
. The shaft
34
includes rollers that further advance the substrate into the remainder of the printer.
In the prior art most electrostatographic printing machines used shafts made from solid materials such as steel and aluminum. Functional features or elements, such as rollers or gears, were then individually mounted on the shaft or were formed in place using metal working techniques such as turning, milling and grinding. Therefore, the completed shaft required significant manual labor. While satisfactory in many respects, the resulting shaft assemblies were rigid, heavy, and costly.
While rigid shafts are beneficial in many applications, in other applications some flexibility is beneficial. For example, when a rigid shaft is used to couple a driven element to a drive element careful alignment is required. Even a relatively minor misalignment can introduce destructive bending, vibration, and torque. However, flexible shafts can reduce alignment problems. In addition to reducing alignment problems highly flexible shafts can transmit forces around bends and corners.
Attempts have been made to provide shaft assemblies with reduced weight and cost. One approach is to use a composite shaft process. The composite shaft process may be more fully understood with reference to U.S. Pat. No. 5,439,916; U.S. Pat. No. 5,876,288; and U.S. Pat. 5,683,641. The composite shaft process utilizes a hollow metal tube into which slits or holes are machined through the wall of the tube. The tube is then placed in a molding machine and a moldable material is injected into the opening on the end of the tube and passed through the slits or holes to fill functional features formed in a mold cavity. While the composite shaft process provides for improved performance and reduce costs, the use of a cylindrical metal tube adds costs to the shaft assembly.
U.S. patent application Ser. No. 09/293,346, entitled “Hollow Shafts with Gas Assist Molding,” filed on Apr. 16, 1999 and U.S. patent application Ser. No. 09/293,098, entitled “Plastic Shafts with Molded Core and External Feature,” filed on Apr. 16, 1999 teach a molding process for plastic tubes. According to those patents a hollow plastic tube having slits or holes is placed in a molding machine. A moldable material is injected into the slits or holes via the end of the tube. The moldable material passes through the slits or holes to fill functional features in a mold cavity.
While the teachings of U.S. patent application Ser. No. 09/293,346 and U.S. patent application Ser. No. 09/293,098 are beneficial, they produce rigid shafts. Therefore, it would be even more beneficial to extend those teachings to enable production of flexible shaft assemblies.
SUMMARY OF THE INVENTION
The principles of the present invention provide for molded, flexible shaft assemblies. A molded, flexible shaft assembly according to the principles of the present invention is comprised of at least two rigid, tubular, shell-like portions containing, and linked together by, a flexible, moldable material. Beneficially the moldable material is polyurethane.


REFERENCES:
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patent: 4917653 (1990-04-01), Collucci
patent: 5439416 (1995-08-01), Jaskowiak
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patent: 5744238 (1998-04-01), Limperis et al.
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patent: 5893210 (1999-04-01), Takei et al.
patent: 5989473 (1999-11-01), Haverty
patent: 6117018 (2000-09-01), Tanada
U.S. Pat. application Ser. No. 09/293,346, filed on Apr. 16, 1999, entitled “Hollow Shafts with Gas Assist Molding”.
U.S. Pat. application Ser. No. 09/293,098, filed on Apr. 16, 1999, entitled “Plastic Shafts with Molded Core and External Feature”.

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