U.S. patent application number 10/502230 was filed with the patent office on 2005-12-08 for caterpillar traction apparatus.
Invention is credited to Jenkins, Daniel Owen, Jenkins, Peter David.
Application Number | 20050269187 10/502230 |
Document ID | / |
Family ID | 9929793 |
Filed Date | 2005-12-08 |
United States Patent
Application |
20050269187 |
Kind Code |
A1 |
Jenkins, Peter David ; et
al. |
December 8, 2005 |
Caterpillar traction apparatus
Abstract
A caterpillar traction apparatus (110), wherein two pairs of
pulleys (122 & 123, 132 & 133) can be driven at different
speeds, so that the linear member (40) being driven by the
mechanism is subjected to either compression or extension
forces.
Inventors: |
Jenkins, Peter David; (
Framlingham, GB) ; Jenkins, Daniel Owen;
(Framlingham, GB) |
Correspondence
Address: |
Edward M Keating
Cook Alex McFarron Manzo Cummings & Mehler
200 W Adams Street
Suite 2850
Chicago
IL
60606
US
|
Family ID: |
9929793 |
Appl. No.: |
10/502230 |
Filed: |
July 19, 2005 |
PCT Filed: |
January 24, 2003 |
PCT NO: |
PCT/GB02/00273 |
Current U.S.
Class: |
198/626.5 ;
198/626.1 |
Current CPC
Class: |
B29C 48/355 20190201;
B65G 37/005 20130101; B65G 15/14 20130101; Y10T 156/1741 20150115;
B65G 2201/0217 20130101; B29C 48/06 20190201; B65H 51/14 20130101;
B29C 48/09 20190201 |
Class at
Publication: |
198/626.5 ;
198/626.1 |
International
Class: |
B65H 005/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 26, 2002 |
GB |
0201793.7 |
Claims
1. A caterpillar traction apparatus comprising first and second
extensive traction members, the first traction member being driven
by and entrained around first and second rotatable members and the
second traction member being driven by and entrained around third
and fourth rotatable members, each of the rotatable members being
addressed by drive means such that the first and third rotatable
members can be driven at a first speed and the second and fourth
rotatable members can be driven at a second speed, the first speed
not being equal to the second speed.
2. A caterpillar traction apparatus according to claim 1, wherein
the difference between the first speed and the second speed is
between 1% and 10%.
3. A caterpillar traction apparatus according to claim 2, wherein
the difference between the first speed and the second speed is
4%.
4. A caterpillar traction apparatus according to claim 1, wherein
the second speed is less than the first speed.
5. A caterpillar traction apparatus according to any one of claims
1 to 3, wherein the second speed is greater than the first
speed.
6. A caterpillar traction apparatus according to claim 1, in which
the first and second extensible traction members are extended in a
direction significantly parallel to their direction of motion.
7. A caterpillar traction apparatus according to claim 1, in which
the first and second extensible traction members are extended in a
direction significantly perpendicular to their direction of
motion.
8. A caterpillar traction apparatus according to claim 1, wherein
the first and second extensible traction members are capable of
sustained extensions of 10% or greater.
9. A caterpillar traction apparatus according to claim 8, wherein
the extensible traction members comprise rubber.
10. A caterpillar traction apparatus according to claim 8 or claim
9, wherein the extensible traction members comprise a compressible
polymer.
11. A method of processing a linear member within a mechanical
caterpillar apparatus according to any of claims 1 to 4 and 6 to 9,
wherein the processing of the linear member is effected by the
difference between the first speed and the second speed.
12. A method of processing a linear member according to claim 1,
wherein the difference between the first speed and the second speed
compresses linearly the linear member.
13. A method of processing a liner member according to claim 1,
wherein the difference between the first speed and the second speed
extends linearly the linear member.
Description
[0001] This invention relates to the field of caterpillar traction
apparatuses.
[0002] Caterpillar traction apparatus are commonly used in the
manufacturing industry to transport products along assembly lines
and from one stage in the manufacturing process to the next. In
particular, the cable manufacturing industry uses caterpillar
traction apparatus to transport extruded plastic tubes and other
cable elements between different pieces of equipment, for example
between an extruder and a stranding machine.
[0003] According to a first aspect of the invention there is
provided a caterpillar traction apparatus comprising first and
second extensible traction members, the first traction member being
driven by and entrained around first and second rotatable members
and the second traction member being driven by and entrained around
third and fourth rotatable members, each of the rotatable members
being addressed by drive means such that the first and third
rotatable members can be driven at a first speed and the second and
fourth rotatable members can be driven at a second speed, the first
speed not being equal to the second speed.
[0004] The difference between the first speed and the second speed
may be between 1% and 10%, and in particular the difference between
the first speed and the second speed may be 4%. The second speed
may be less than the first speed or alternatively the second speed
may be greater than the first speed. The first and second
extensible traction members may be extended in a direction
significantly parallel to their direction of motion and/or the
first and second extensible traction members may be extended in a
direction significantly perpendicular to their direction of
motion.
[0005] The first and second extensible traction members are
preferably capable of sustained extensions of 10% or greater, and
they may comprise rubber and/or a compressible polymer.
[0006] According to a second aspect of the invention there is
provided a method of processing a linear member within a
caterpillar traction apparatus according to the first aspect,
wherein the processing of the linear member is effected by the
difference between the first speed and the second speed. The
difference between the first speed and the second speed may
compress linearly the linear member or alternatively the difference
between the first speed and the second speed may extend linearly
the linear member.
[0007] The invention will now be described, by way of example only,
with reference to the following Figures in which:
[0008] FIG. 1 shows a schematic depiction of a known caterpillar
traction mechanism;
[0009] FIG. 2 shows a schematic depiction of a caterpillar traction
mechanism according to the present invention; and
[0010] FIG. 3 shows an alternative embodiment of schematic
depiction of a caterpillar traction mechanism according to the
present invention.
[0011] FIG. 1 shows a schematic depiction of a known caterpillar
traction apparatus. The caterpillar traction apparatus 10 comprises
an upper half 20 and a lower half 30 that co-operate to advance a
linear member 40, such as an extruded tube, pipe or cable.
[0012] The upper half 20 comprises a first belt 21, first and
second pulleys 22, 23 and a plurality of compression rollers 24,
25, 26, 27, 28. The first belt 21 is substantially un-extended
under the tensile loads experienced during normal operation of the
apparatus 10. Typically such belts have a soft rubber outer layer
in order to increase the grip on the linear member 40 being driven
by the apparatus and comprise a substantially inextensible strength
member, for example, woven aramid fibres or braided steel, in the
centre of the belt, to provide the belt's capacity to resist
extension. The belt may also have a tread pattern on its inner
surface to increase the traction between the first belt and the
first and second pulleys.
[0013] The first pulley 22 is a driven pulley, which is in
driveable connection with a motor (not shown) whilst second pulley
23 is an idle pulley. The compression rollers 24-28 are free to
rotate but act to urge the first belt against the linear member 40,
thereby increasing the grip between the first belt and the linear
member.
[0014] The lower half is of a similar construction to the upper
half and comprises a second belt 31, third and fourth pulleys 32,
33 and a plurality of compression rollers 34, 35, 36, 37, 38. The
second belt 31 is substantially un-extended under the tensile loads
experienced during normal operation of the apparatus 10 and has a
similar construction and performance to the first belt (see
above).
[0015] The third pulley 32 is a driven pulley, which is in
driveable connection with a motor (not shown) whilst fourth pulley
33 is an idle pulley. The compression rollers 34-38 are free to
rotate but act to urge the second belt against the linear member
40.
[0016] The traction apparatus advances the linear member by the
action of the motor causing the first pulley 22 to rotate in a
counter-clockwise direction and the third pulley 32 to rotate in a
clockwise direction. The two sets of compression rollers work in
combination to improve the grip of the first and second belts on
the linear member, increasing the efficiency with which the linear
member is moved by the traction apparatus.
[0017] FIG. 2 shows a caterpillar traction apparatus according to
the present invention, which comprises an upper half 120 and a
lower half 130 that co-operate to advance a linear member 40, such
as an extruded tube, pipe or cable. The upper half 120 comprises a
first belt 121, first and second pulleys 122, 123 and a plurality
of compression rollers 124, 125, 126, 127, 128. The first belt 121
has a soft rubber outer layer in order to increase the grip on the
linear member 40 being driven by the apparatus and a tread pattern
on the inner surface to increase the traction between the first
belt and the first and second pulleys. Both the first pulley 122
and the second pulley 123 are driven pulleys, which have a
respective driveable connection with a motor (not shown). The
compression rollers 124-128 are free to rotate but act to urge the
first belt against the linear member 40.
[0018] The lower half is of a similar construction to the upper
half and comprises a second belt 131, third and fourth pulleys 132,
133 and a plurality of compression rollers 134, 135, 136, 137, 138.
The second belt 131 has a soft rubber outer layer and a tread
pattern on its inner surface, in a similar manner to the first
belt. The third pulley 132 and fourth pulley 133 are driven
pulleys, which have a respective driveable connection with a motor
(not shown). The compression rollers 134-138 are free to rotate but
act to urge the second belt against the linear member 40. Both sets
of compression rollers, 124-128 & 134-138 act in a direction
that is substantially normal to the linear member being passed
through the apparatus
[0019] In contrast to the known arrangement described above and
shown in FIG. 1, both the first and second belts 121, 131 are
elastic and are capable of sustaining a significant elongation, for
example of 10-15%. Additionally, the second and fourth pulleys 123,
133 can be moved parallel to the axis of the linear member to
stretch the first and second belts respectively.
[0020] The traction apparatus 110 according to the present
invention can be used to linearly compress a linear member 40 as it
passes through the apparatus. The second and fourth pulleys are
moved so as to extend the first and second belts into the positions
indicated by the dotted lines in FIG. 2. This strains the first and
second belts, giving an extension of, for example, 5%. The belts
are then rotated by driving each of the pulleys. The first and
second pulleys 122, 123 are both driven in a counter-clockwise
direction and the third and fourth pulleys 132, 133 are driven in a
clockwise direction The second and fourth pulleys 123, 133 are
driven at a lower speed than are the first and third pulleys 122,
132, for example 4% slower than the first and third pulleys. Each
pulley may have a dedicated motor and drive circuitry, all of which
are controlled centrally, or the apparatus may have a single motor
that is connected to each pulley via respective gearings and drive
circuitry.
[0021] This differential speed for the two sets of pulleys means
that the first and second belts will be subject to different levels
of strain in different regions of each belt. In the `interior
portion` of the two belts, where the first belt is advanced from
the first pulley to the second pulley and the second belt is
advanced from the third pulley to the fourth pulley, the first and
second belts are relaxed by 4% due to the speed differential,
leaving the belts strained at 1%. Similarly, in the `exterior
portion` of the two belts, where the first belt is returned from
the second pulley to the first pulley and the second belt is
returned from the fourth pulley to the third pulley, the first and
second belts are strained by a further 4%, giving a 9% strain in
the `exterior portion` of the first and second belts.
[0022] As the linear member passes through the apparatus it is
pulled into the apparatus by the first and second pulleys at a
speed that is 4% greater than the speed at which the third and
fourth pulleys are driving the linear member out of the apparatus.
Thus, the linear member is subjected to a 4% compression whilst it
is being driven through the apparatus. If necessary, the force
applied by the compression rollers can be increased to reduce the
possibility that the compressive forces induce buckling in the
linear member.
[0023] By compressing the linear member the linear member can be
conditioned by reducing the level of strain energy stored within
the member. This strain energy is incorporated within the linear
member during extrusion (or other manufacturing processes). The
reduction of the stored strain energy reduces the potential for the
linear member to relax. This is advantageous because it makes the
subsequent storage and processing of the linear member more simple.
Any such relaxation could cause an undesired change in length of
the linear member, during future temperature or other environmental
changes. This is of advantage when used with the tube processing
equipment described in our European patent EP-B-0 765 214.
[0024] Furthermore, the apparatus of the present invention can be
operated in a different manner to provide a tensile strain on the
linear member, rather than a compressive strain, as it is driven
through the apparatus.
[0025] To provide a tensile strain it is necessary to drive the
second and fourth pulleys faster than the first and third pulleys,
such that the `interior portion` of the two belts experiences a
greater strain than the `exterior portion` of the two belts,
causing the linear member to be pulled out of the apparatus by the
second and fourth pulleys at a greater speed than it is driven into
the apparatus by the first and third pulleys. The advantage of
subjecting the linear member to a tensile strain is that polymer
chains in an extruded tube can obtain a greater degree of
orientation, leading to an increased tensile strength.
[0026] From the foregoing discussion it will be apparent that the
capacity of the apparatus to apply compression (or extension) to a
linear member is determined by the amount of strain that the first
and second belts can withstand, and the frictional grip between the
belts and the driven pulleys. Known belts for caterpillar apparatus
are designed to operate without undergoing significant extension,
as the energy that is used to extend the belts is lost from the
primary purpose of the caterpillar, that is transporting an item.
For example, a typical known belt for a caterpillar apparatus would
have a normal working strain range of 2-5% with an ultimate tensile
strain of 10%. For the present invention it is envisaged that the
extensible belts would have a normal working strain range of 10-20%
with a much greater ultimate tensile strain value.
[0027] FIG. 3 shows an alternative embodiment of the present
invention, in which the second and fourth pulleys are not moved to
extend the belts. Instead, the belts are extended by providing a
plurality of rollers 300, 301, 302 & 303. The rollers are free
to rotate and can be moved outwards (as shown in FIG. 3) in order
to extend the belts. The rollers are mounted on sliding blocks
which comprise tensioning members such that the blocks can be
secured in position. The degree of belt extension will increase
with the distance that the rollers are moved from their initial
positions. The position of the extended belts are shown using
broken lines in FIG. 3. It will be understood that that the method
of extending the belts described in relation to FIG. 2 could be
combined with the method of extending the belts described in
relation to FIG. 3.
[0028] FIG. 4 shows a further embodiment of the present invention
in which eight additional guide rollers 201, 202, . . . , 208 are
provided. Guide rollers 201, 202, 203 and 204 co-operate with the
first extensible belt 121 whilst guide rollers 205, 205, 207 and
208 co-operate with the second extensible belt 131. FIG. 4a shows
guide rollers 202, 204 and 206 and FIG. 4b, which is a section of
FIG. 4a along the line AA, shows guide rollers 201, 202, 203 and
204. Guide rollers 205 and 207 are behind guide rollers 206 and 208
respectively in FIG. 4a and beneath guide rollers 201 and 203
respectively in FIG. 4b.
[0029] All of the guide rollers 201-208 are free to rotate and act
as guides to maintain their respective extensible belts
symmetrically positioned on the driven rollers 121, 123 and 131,
133 respectively. When the extensible belts are under compression
in the `interior portion`, i.e. the speed differential is such that
all of the extensive strain is relieved and compressive stain is
now occurring in the belts 121 and 131, they have a tendency to
`snake` across the compression rollers 124-128 and 134-138
respectively. This `snaking` can lead to the belts drifting off the
driven rollers. The addition of the guide rollers 201-208 maintain
the position of the extensible belts relative to the compression
rollers and the drive rollers. It will be understood that the
embodiment of the invention described above with reference to FIG.
4 may be used in conjunction with any of the other embodiments of
the invention described above.
[0030] It will be understood that rather than moving the second and
fourth pulleys to strain the belts, the belts could be provided
`too short` for the distance between the first and third pulleys
and the second and fourth pulleys, such that the belts are
tensioned by fitting them over their respective pairs of pulleys.
However, this alternative method is not preferred due to the
increased difficulty of fitting the strained belts over the
pulleys.
[0031] Furthermore, it is possible to operate the apparatus
according to the present invention without pre-straining the belts
by moving the pulleys or by using belts that are too short and this
is achieved by providing the differential strain in the `interior
portion` and the `exterior portion` solely by varying the first and
second speeds, however it is believed that the tensioning of the
belt will require so much energy from the driven pulleys that there
will be less energy available to process the linear member being
driven through the apparatus and under certain conditions it may
not be possible to transfer sufficient energy to the linear member
to achieve the desired degree of processing.
[0032] It is also believed that the differential speed between the
two sets of pulleys can be increased by driving the slower moving
set of pulleys in the reverse direction to that described above,
however this will lead to significant heat generation and increased
wear occurring to the inner surface of the belts. Conventionally,
caterpillar machines are arranged to provide maximum drive transfer
and to minimise belt slippage, but some features, such as
`multi-vee` drive pulleys and belt profiles, may be altered in
order to allow significant slippage to enable one set of pulleys to
be driven in reverse without causing any significant problems.
[0033] It is a known characteristic of rubber that it is
incompressible. Therefore, if an extensible belt comprises a
significant proportion of rubber it will be necessary to extend the
belt before any compression can be developed within a region of the
belt. Furthermore, as the compression is being developed by working
against the extension previously generated within the belt, the
level of compression that can be developed will be limited by the
level of extension present in the belt. Clearly belts could be made
with other materials, either in place of or in addition to rubber,
such as a foamed polymer, that are capable of being compressed and
thus do not need to be extended before compression can be developed
in a region of the belt.
* * * * *