U.S. patent application number 10/580127 was filed with the patent office on 2008-11-06 for crawler belt, crawler unit and method for manufacturing crawler belt.
This patent application is currently assigned to The Circle for the Promotion of Science and Engineering. Invention is credited to Shigeo Hirose, Shingo Tsukui.
Application Number | 20080272647 10/580127 |
Document ID | / |
Family ID | 34616336 |
Filed Date | 2008-11-06 |
United States Patent
Application |
20080272647 |
Kind Code |
A9 |
Hirose; Shigeo ; et
al. |
November 6, 2008 |
Crawler belt, crawler unit and method for manufacturing crawler
belt
Abstract
Means to Solve A crawler belt 20 comprises an endless steel belt
21 (high-tensile-strength belt) and a belt main body 22 made of
rubber and attached around an outer periphery of the steel belt 21.
The steel belt 21 has engagement holes 21a arranged at even
intervals in a circumferential direction thereof. The belt main
body 22 has escape recesses 23a formed therein. A wheel 10 has
projections 12a arranged at even intervals in a circumferential
direction on an outer peripheral surface thereof. The projections
12a are adapted to be engaged with the engagement holes 21a of the
steel belt 21 and at the same time to enter the escape recesses 23a
of the belt main body 22.
Inventors: |
Hirose; Shigeo; (Tokyo,
JP) ; Tsukui; Shingo; (Aichi, JP) |
Correspondence
Address: |
OSHA LIANG L.L.P.
1221 MCKINNEY STREET
SUITE 2800
HOUSTON
TX
77010
US
|
Assignee: |
The Circle for the Promotion of
Science and Engineering
2-12-1, Ookayama, Meguro-ku
Tokyo
JP
152-8550
Topy Kogyo Kabushiki Kaisha
5-9, Yonbancho, Chiyoda-ku
Tokyo
JP
102-8448
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20070145820 A1 |
June 28, 2007 |
|
|
Family ID: |
34616336 |
Appl. No.: |
10/580127 |
Filed: |
November 18, 2004 |
PCT Filed: |
November 18, 2004 |
PCT NO: |
PCT/JP04/17161 |
371 Date: |
May 19, 2006 |
Current U.S.
Class: |
305/167 |
Current CPC
Class: |
B62D 55/244 20130101;
B62D 55/24 20130101 |
Class at
Publication: |
305/167 |
International
Class: |
B62D 55/24 20060101
B62D055/24 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 20, 2003 |
JP |
2003-390483 |
Claims
1. A crawler belt comprising an endless high-tensile-strength belt
(21) and a belt main body (22) made of elastic material and
attached to an outer periphery of said high-tensile-strength belt,
said high-tensile-strength belt (21) having engagement holes (21a)
arranged at even intervals in a circumferential direction thereof,
said belt main body (22) having escape recesses (23a) formed at
locations corresponding to said engagement holes of said
high-tensile-strength belt.
2. A crawler unit comprising a plurality of wheels (10) disposed
separately in a front and rear direction and a crawler belt (20)
trained about said wheels, wherein said crawler belt (20) comprises
an endless high-tensile-strength belt (21) and a belt main body
(22) made of elastic material and attached to an outer periphery of
said high-tensile-strength belt, said high-tensile-strength belt
(21) having engagement holes (21a) arranged at even intervals in a
circumferential direction thereof, said belt main body having
escape recesses (23a) formed at locations corresponding to said
engagement holes of said high-tensile-strength belt, and wherein a
driving wheel of said plurality of wheels (10) has engagement
projections (12a) arranged at even intervals in a circumferential
direction on an outer peripheral surface thereof, said engagement
projections (12a) being adapted to be engaged with said engagement
holes (21a) of said high-tensile-strength belt (21) of said crawler
belt (20) and at the same time to enter said escape recesses (23a)
of said belt main body (22).
3. A crawler unit according to claim 2, wherein outer peripheral
surfaces of said plurality of wheels (10) are generally cylindrical
surfaces.
4. A crawler unit according to claim 3, wherein said engagement
holes (21a) of said high-tensile-strength belt (21) have a
generally circular shape and said engagement projections (12a) of
said wheel (10) have a generally semi-spherical shape.
5. A crawler unit according to claim 2, wherein said crawler unit
further comprises a pair of side plates (30) extending in a front
and rear direction to cover opposite side surfaces of said
plurality of wheels (10), said belt main body (22) comprising an
endless base part (23) and shielding brims (24, 24') continuously
formed along an entire length on opposite sides of said base part,
edges of said shielding brims contacting peripheral edges of said
side plates.
6. A crawler unit according to claim 2, wherein said belt main body
(22) includes an endless base part (23) and a plurality of tread
lugs (26) formed spacedly on an outer periphery of and extending in
a width direction of said base part (23), said tread lugs having a
planer shape bent at least at one point, height of said tread lugs
being not less than 3 times and not greater than 7 times as large
as its thickness.
7. A method for manufacturing a crawler belt, the method comprising
steps of: preparing a first mold (70) having a plurality of mold
projections (74a) arranged at even intervals on a molding surface
thereof and a second mold (80) having a plurality of lug mold
recesses (86) opening at a molding surface thereof; setting an
endless high-tensile-strength belt (21) having engagement holes
(21a) arranged at even intervals in a circumferential direction
thereof on said first mold (70) with said mold projections (74a)
fitted into said engagement holes; and molding an elastic material
between said first mold and said second mold to obtain a belt main
body (22) or a part (22') of said belt main body (22) attached to
an outer periphery of at least a part of said high-tensile-strength
belt, at the same time forming escape recesses (23a) by allowing
said molding projections (74a) of said first mold (70) to press
into said elastic material and forming tread lugs (26) by allowing
said elastic material to enter said lug mold recesses (86) of said
second mold (80).
8. A method for manufacturing a crawler belt, the method comprising
steps of: preparing a lower mold (70) having a plurality of mold
projections (74a) arranged at even intervals on an upper surface
thereof and an upper mold (80) having a plurality of lug mold
recesses (86) opening at an lower surface thereof; positioning an
endless high-tensile-strength belt (21) having engagement holes
(21a) arranged at even intervals in a circumferential direction
thereof by placing a part of said high-tensile-strength belt (21)
on said lower mold (70) and by fitting said mold projections (74a)
of said lower mold into said engagement holes of said
high-tensile-strength belt; placing an elastic material on said
lower mold and lowering said upper mold to mold a part (22') of a
belt main body (22) on an outer periphery of said
high-tensile-strength belt (21) between said upper mold and said
lower mold, at the same time forming escape recesses (23a) by
allowing said mold projections (74a) of said lower mold (70) to
press into said elastic material and forming tread lugs (26) by
allowing said elastic material to enter said lug mold recesses (86)
of said upper mold (80); and molding said endless belt main body
(22) all around the periphery of said high-tensile-strength belt
(21) by moving said high-tensile-strength belt (21) to place a new
part of said high-tensile-strength belt (21) on said lower mold
(70), said new part adjoining said part where said part (22') of
said belt main body (22) was molded, molding another part (22') of
said belt main body on said new part of said high-tensile-strength
belt in the foregoing way, and by repeating the procedure.
9. A method for manufacturing a crawler belt according to claim 8,
wherein mold pins (74) are removably inserted into said upper
surface of said lower mold (70) and head parts of said mold pins
are provided as said mold projections (74a).
Description
TECHNICAL FIELD
[0001] This invention relates to a crawler belt and a crawler unit
used in a crawler structure of a light-weight robot, etc. and a
method for manufacturing the crawler belt.
BACKGROUND ART
[0002] Rubber crawler belts to be used in a light-weight robot,
etc. have been developed. The crawler belts have tread lugs on
outer periphery thereof and equally-spaced projections for engaging
with a wheel or a sprocket on inner periphery thereof. Such crawler
belts, however, tend to stretch too much, go slack and come off the
wheel after long use. Sometimes they may break due to lack of
strength. If the crawler belts are increased in thickness to
overcome these shortcomings, they are increased in weight, too.
[0003] To address the above-mentioned problem, technologies have
been developed to reinforce the crawler belts by embedding an
endless high-tensile-strength belt made of thin metal belt, etc. in
a rubber-made main body of the crawler belt as disclosed in the
patent documents 1 to 3 listed below.
Patent Document 1: Japanese Patent Application Laid-Open No.
H6-156333
Patent Document 2: Japanese Patent Application Laid-Open No.
H6-199253
Patent Document 3: Japanese Patent Application Laid-Open No.
H6-329057
DISCLOSURE OF THE INVENTION
Problem to be Solved by the Invention
[0004] Crawler belts disclosed in the Patents Documents 1 to 3 may
be enhanced in strength, but can be reduced in weight only to a
limited degree due to projections for engaging with a wheel or a
sprocket.
[0005] Recently, a robot for searching and rescuing people trapped
under the rubble at the time of disasters such as an earthquake and
other light-duty robots have been developed. In such light-weight
robots, further reduction in weight of a crawler unit is desired.
However, reinforced crawler belts as disclosed in the above-listed
patent documents fail to meet the demand of weight reduction.
MEANS FOR SOLVING THE PROBLEM
[0006] The present invention has been made in order to solve the
above mentioned problem. According to the present invention, there
is provided a crawler belt comprising an endless
high-tensile-strength belt (21) and a belt main body (22) made of
elastic material and attached to an outer periphery of the
high-tensile-strength belt, the high-tensile-strength belt (21)
having engagement holes (21a) arranged at even intervals in a
circumferential direction thereof, the belt main body (22) having
escape recesses (23a) formed at locations corresponding to the
engagement holes of the high-tensile-strength belt.
[0007] According to the present invention, there is also provided a
crawler unit comprising a plurality of wheels (10) disposed
separately in a front and rear direction and a crawler belt (20)
trained about the wheels, wherein
[0008] the crawler belt (20) comprises an endless
high-tensile-strength belt (21) and a belt main body (22) made of
elastic material and attached to an outer periphery of the
high-tensile-strength belt, the high-tensile-strength belt (21)
having engagement holes (21a) arranged at even intervals in a
circumferential direction thereof, the belt main body having escape
recesses (23a) formed at locations corresponding to the engagement
holes of the high-tensile-strength belt, and wherein
[0009] a driving wheel of the plurality of wheels (10) has
engagement projections (12a) arranged at even intervals in a
circumferential direction on an outer peripheral surface thereof,
the engagement projections (12a) being adapted to be engaged with
the engagement holes (21a) of the high-tensile-strength belt (21)
of the crawler belt (20) and at the same time to enter the escape
recesses (23a) of the belt main body (22).
[0010] In the crawler belt and the crawler unit as constructed
above, owing to the endless high-tensile-strength belt incorporated
in the crawler belt, the crawler belt has a high tensile strength
and is free from undesirable events such as having been stretched
too much and coming off the wheel. It is free from breakage,
either. Moreover, since the engagement holes are formed on the
high-tensile-strength belt and the projections of the wheel are
adapted to be engaged with the engagement holes, the belt main body
made of elastic material is not required to have projections for
engaging with a wheel. This further contributes to the reduction of
weight.
[0011] Preferably, outer peripheral surfaces of the plurality of
wheels (10) are generally cylindrical surfaces. More preferably,
the engagement holes (21a) of the high-tensile-strength belt (21)
have a generally circular shape and the engagement projections
(12a) of the wheel (10) have a generally semi-spherical shape. This
contributes to the reduction of noise.
[0012] Preferably, the crawler unit further comprises a pair of
side plates (30) extending in a front and rear direction to cover
opposite side surfaces of the plurality of wheels (10), the belt
main body (22) comprising an endless base part (23) and shielding
brims (24, 24') continuously formed along an entire length on
opposite sides of the base part, edges of the shielding brims
contacting peripheral edges of the side plates. The shielding brims
serves to shield an inner space between the side plates, thus
preventing foreign substances such as sand and dusts from entering
between the crawler belt and the wheels.
[0013] More preferably, the shielding brim has a tapered
cross-section and is elastically deformed as it contacts
semi-circular peripheral edges of a front and rear end portions of
the side plate. A part of the crawler belt which is placed around
the wheel is subjected to a force to cause the edge of the
shielding brim to be waved. But the edge of the shielding brim can
contact the side plate securely without being waved because the
edge part of the shielding brim is elastically deformed as it
contacts the side plates.
[0014] More preferably, upper and lower edges of the side plates
located between the wheels are made of a seal member, the seal
member having smaller elastic coefficient than the shielding brim,
the seal member being deformed as it contacts the edge of the
shielding brim. This permits the shielding brim and the seal member
to be securely maintained in contact with each other even when the
crawler belt flap between the wheels.
[0015] Preferably, the belt main body (22) includes an endless base
part (23) and a plurality of tread lugs (26) formed spacedly on the
outer periphery of and extending in a width direction of the base
part (23), the tread lugs having a planer shape bent at least at
one point, height of the tread lugs being not less than 3 times and
not greater than 7 times as large as its thickness. This enables a
robot, etc. to keep running without slipping even if it encounters
the rubble, etc. as it runs on the unleveled ground, by allowing
the tread lugs to be elastically deformed and grip the rubble, etc.
Moreover, although the tread lugs are high and slim, they can
support the self-weight of the robot, etc. since they have bent
planer shapes.
[0016] According to the present invention, there is provided a
method for manufacturing a crawler belt, the method comprising
steps of:
[0017] preparing a first mold (70) having a plurality of mold
projections (74a) arranged at even intervals on a molding surface
thereof and a second mold (80) having a plurality of lug mold
recesses (86) opening at a molding surface thereof;
[0018] setting en endless high-tensile-strength belt (21) having
engagement holes (21a) arranged at even intervals in a
circumferential direction thereof on the first mold (70) by fitting
the mold projections (74a) into the engagement holes; and
[0019] molding an elastic material between the first mold and the
second mold to obtain a belt main body (22) or a part (22') of the
belt main body (22) attached to an outer periphery of at least a
part of the high-tensile-strength belt, at the same time forming
escape recesses (23a) by allowing the molding projections (74a) of
the first mold (70) to press into the elastic material and forming
tread lugs (26) by allowing the elastic material to enter the lug
mold recesses (86) of the second mold (80).
[0020] In the method described above, a positioning device is not
necessary because the engagement holes of the high-tensile-strength
belt can be used as a positioning device. Moreover, the tread lugs
can be molded easily and inexpensively because molding is
accomplished by allowing the elastic material to enter the lug mold
recess.
[0021] According to the present invention, there is further
provided a method for manufacturing a crawler belt, the method
comprising steps of:
[0022] preparing a lower mold (70) having a plurality of mold
projections (74a) arranged at even intervals on an upper surface
thereof and an upper mold (80) having a plurality of lug mold
recesses (86) opening at an lower surface thereof;
[0023] positioning an endless high-tensile-strength belt (21)
having engagement holes (21a) arranged at even intervals in a
circumferential direction thereof by placing a part of the
high-tensile-strength belt (21) on the lower mold (70) and by
fitting the mold projections (74a) of the lower mold into the
engagement holes of the high-tensile-strength belt;
[0024] placing an elastic material on said lower mold and lowering
said upper mold to mold a part (22') of a belt main body (22) on an
outer periphery of the high-tensile-strength belt (21) between the
upper mold and the lower mold, at the same time forming escape
recesses (23a) by allowing the mold projections (74a) of the lower
mold (70) to press into the elastic material, and forming tread
lugs (26) by allowing the elastic material to enter the lug mold
recesses (86) of the upper mold (80); and
[0025] molding the endless belt main body (22) all around the
periphery of the high-tensile-strength belt (21) by moving the
high-tensile-strength belt (21), to place a new part of the
high-tensile-strength belt (21) on the lower mold (70), the new
part adjoining the part where the part (22') of the belt main body
(22) was molded, molding another part (22') of the belt main body
on said new part of said high-tensile-strength belt in the
foregoing way, and by repeating the procedure.
[0026] In the method described above, the crawler belt can be
manufactured easily and inexpensively without using expensive
equipment. Moreover, a positioning device is not necessary because
the engagement holes of the high-tensile-strength belt can be used
as a positioning device. Moreover, the tread lugs can be molded
easily and inexpensively because molding is accomplished by
allowing the elastic material to enter the lug mold recess.
Furthermore, crawler belts of various circumferential lengths can
be manufactured with the same equipment.
[0027] Preferably, mold pins (74) are removably inserted into the
upper surface of the lower mold (70) and head parts of the mold
pins are provided as the mold projections (74a). By this, after
molding, the molded part of the belt main body and the
high-tensile-strength belt can be removed from the lower mold
without substantial resistance, which contributes to significantly
improve productivity.
ADVANTAGEOUS EFFECT OF THE INVENTION
[0028] According to the present invention, a crawler belt with high
strength and light weight can be obtained. By using the method
according to the present invention, a crawler belt incorporating a
high-tensile-strength belt can be manufactured easily and
inexpensively.
BEST MODE FOR CARRYING OUT THE INVENTION
[0029] First embodiment of the present invention is described below
referring to FIGS. 1 to 11. FIG. 1 shows a crawler structure A,
which constitutes a lower body of a light-duty robot. The crawler
structure comprises a mounting base 1 and a pair of crawler units 2
attached to the left and right of the mounting base 1. An upper
body of the robot is mounted on the mounting base 1. The upper body
may be of various constructions, according to the role of the
robot. For example, a robot for searching people trapped under the
rubble at the time of disasters such as an earthquake has a camera,
a detection sensor and an illuminating device, and a grasping
mechanism for grasping light-weight items, according to
necessity.
[0030] As shown in FIGS. 1and 2, each of the crawler units 2
comprises wheels 10 in the front and rear, an endless crawler belt
20 trained about the wheels 10 and a pair of side plates 30
rotatably supporting the wheels 10 in the front and rear. The side
plate 30 of each of crawler units 2 located on an inner side is
attached to the mounting base 1 at the central portion of the side
plate 30.
[0031] The left and right crawler units 2 are substantially of the
same construction. In each of the crawler units 2, either one of
the wheels 10 in the front or in the rear is connected to an
actuator (not shown) such as an electric motor provided on the side
plate 30 on the inner side and serves as a driving wheel and the
other of the wheels serves as a trailing wheel.
[0032] As shown in FIGS. 2 and 4, outer peripheral surface of the
each of the wheels 10 is a cylindrical surface. The wheel 10 has
semi-spherical engagement projections 12a arranged at even
intervals in a circumferential direction at a center in a width
direction of the outer peripheral surface thereof. In this
embodiment, a diameter of the engagement projection 12a is around 3
millimeters while a width of the wheel 10 is 30 millimeters.
[0033] As shown in FIGS. 2 and 4, the pair of side plates 30 are
disposed to the left and right of the pair of wheels 10. Each of
the side plates 30 is in a shape of an oblong plate elongated in a
front and rear direction. Front and rear end portions of the side
plates 30 cover opposite side surfaces of the pair of wheels 10.
Peripheral edges of front and rear end portions of the side plates
30 are of a semi-circular shape corresponding to the shape of
peripheral edges of the wheel 10.
[0034] As shown in FIG. 4, the peripheral edge of the side plate 30
has a tapered cross section all around the periphery and its outer
face is an inclined surface 30c.
[0035] As shown in FIG. 3, the crawler belt 20 includes an endless
steel belt 21 made of stainless steel (or a thin metal belt or a
high-tensile-strength belt) and an endless belt main body 22, the
belt main body 22 being made of rubber (or an elastic material)
such as SBR and urethane rubber and being attached all around the
outer periphery of the steel belt 21 by vulcanization bonding,
etc.
[0036] The steel belt 21 is constructed by welding opposite ends of
an elongated thin belt of a thickness of from 0.05 to 1.0
millimeters (0.15 millimeters in this embodiment). A width of the
steel belt 21 is generally same as that of the wheel 10. The steel
belt 21 has circular engagement holes 21a arranged at even
intervals (the same interval as that of the engagement projections
12a of the wheel 10) in a circumferential direction at a center in
the width direction thereof. A diameter of the engagement holes 21a
is the same as or a slightly greater than that of the engagement
projections 12a.
[0037] The steel belt 21 according to this embodiment is extremely
thin compared with a base part 23 (of a thickness of 3 millimeters)
to be described later. The thickness of the steel belt 21 is
exaggerated in drawings.
[0038] As shown in FIGS. 1 and 3, the belt main body 22 integrally
includes an endless base part 23 of a width greater than that of
the steel belt 21, a shielding brim 24 formed on opposite sides in
a width direction of the base part 23 and tread lugs 26 spacedly
formed on an outer periphery of the base part 23. The base part 23
has generally semi-spherical escape recesses 23a arranged at center
in the width direction thereof, at locations corresponding to the
engagement holes 21a of the steel belt 21 to communicate with the
engagement halls 21a.
[0039] The crawler belt 20 is placed around half of the periphery
of the wheels 10 in the front and rear. As shown in FIG. 4, in an
area covering half of the periphery of the wheel 10, the steel belt
21 contacts the outer peripheral surface of the wheel 10 directly,
the engagement projections 12a of the wheel 10 engaging the
engagement holes 21a of the steel belt 21 and at the same time
entering the escape recesses 23a of the base part 23.
[0040] The shielding brim 24 is formed continuously all around the
periphery of the belt main body 22. The shielding brim 24 extends
radially inward from the base part 23. The outer surface of the
edge of the shielding brim 24 is an inclined surface. By this, the
shielding brim 24 is given a tapered cross section, thereby being
allowed to be deformed easily.
[0041] The tread lug 26 extends in a width direction of the crawler
belt 20 and has a trapezoidal longitudinal section. In this
embodiment, a thickness of the tread lug 26 is 5 millimeters in
lower base and 3 millimeters in upper base in longitudinal section
while its height is 15 millimeters. The tread lug 26 is of an
extremely small thickness for its height and, therefore, has a
small flexural rigidity. As a result, the tread lug 26 is easy to
bend when a force in a longitudinal direction of the crawler belt
20 is applied. Preferably, the height of the tread lug 26 is not
less than 3 times and not greater than 7 times as large as its
thickness (an average thickness or a thickness at center in a
height direction). More preferably, the height of the tread lug 26
is not less than 3.5 times and not greater than 5 times as large as
its thickness. If the height of the tread lug 26 is less than 3
times as large as its thickness, the flexural rigidity of the tread
lug 26 is not small enough. If the height of the tread lug 26 is
greater than 7 times as large as its thickness, the tread lug 26 is
not strong enough in the height direction. The tread lug 26 has a
planer shape bent at the center as shown in FIG. 1. The bending
adds to the strength of the tread lug 26 against load in height
direction, i.e. self-weight of the robot. In this embodiment, as
shown in FIG. 6, bending direction of the tread lugs 26 is changed
every few tread lugs 26.
[0042] In a robot of the above mentioned construction, when the
actuators of the crawler units 2 in the left and right are driven,
the crawler belt 20 is rotated by rotation of the wheels 10
connected to the actuators. As a result, the robot moves.
[0043] Although the belt main body 22 used in the crawler belt 20
is made of rubber, since it is reinforced with the steel belt 21,
it does not stretch even after long use and can be prevented from
coming off the wheel 10. Moreover, the crawler belt 20 can be
greatly reduced in weight. The first reason is that the crawler
belt 20 is reinforced with the thin steel belt 21 without being
increased in thickness. The second reason is that the belt is
engaged with the wheel 10 via the steel belt 21, which eliminates
the necessity of forming projections for engaging with the wheel 10
or a sprocket on the belt main body 22 (refer to the
above-mentioned prior art documents).
[0044] The crawler belt 20 can be surely prevented from coming off
the wheel 10 in a left and right direction since the projections
12a of the wheel 10 fit into the engagement holes 21a of the steel
belt 21.
[0045] In this embodiment, since flexible tread lugs 26 are
provided, the robot can easily move over relatively low rubble S'
having a flat surface as shown in FIG. 7. It is because the tread
lugs 26 are elastically deformed and, accordingly, contact area
with the rubble S' is increased. This allows the tread lugs 26 to
grip the rubble S' well without slipping, and therefore idle
running of the crawler belt 20 can be avoided. This function is
very helpful especially when the rubble S' is wet or sands adhere
to the rubble S'. As shown in FIG. 7, the rubble S' can be gripped
more securely with the two adjoining tread lugs 26 by reducing
interval between adjoining tread lugs 26.
[0046] Although the tread lug 26 is easy to bend, it is strong
enough and is not deformed too much against load in height
direction, i.e. the self-weight of the robot, which allows the
robot to keep moving smoothly. It is because the tread lug 26 has a
bent planer shape, and therefore has high strength in height
direction.
[0047] The shielding brim 24 of the belt main body 22 contacts the
inclined surface 30c of the side plate 30 at the peripheral edge of
the side plate 30 with the shielding brim being elastically
deformed. As a result, an inner space surrounded by the crawler
belt 20 and the pair of side plates 30 is sealed, thereby
preventing foreign substances such as water, sands and dust from
entering into the inner space.
[0048] A part of the crawler belt 20 which is placed around half of
the periphery of the wheels 10 is subjected to a force to cause the
shielding brim 24 to be waved. But the shielding brim 24 can
contact the peripheral edge of the side plate 30 securely without
being waved because the shielding brim 24 is elastically deformed
as it contacts the peripheral edge of the side plates 30.
[0049] Manufacturing equipment and a method for manufacturing the
crawler belt 20 will be described hereinafter. As shown in FIG. 8,
the manufacturing equipment comprises a lower mold 70 (or a first
mold) and an upper mold 80 (or a second mold) that moves up and
down with respect to the lower mold 70.
[0050] The lower mold 70 includes a base section 71 and a molding
section 72 having an inverted U-shaped cross-section, which are
detachable from each other. The lower mold 70 has a hollow
rectangular parallelepiped shape with both ends open. As shown in
FIG. 9, the molding section 72 has receiving holes 72a arranged at
even intervals in a longitudinal direction on an upper surface
thereof. Mold pins 74 are removably received in the receiving holes
72. The mold pin 74 includes a head portion having a semi-spherical
shape and being provided as a mold projection 74a. A pair of linear
auxiliary mold recesses 73 for molding the shielding brim 24 are
formed sandwiching a row of the mold projections 74a on the lower
mold 70.
[0051] The upper mold 80 has a shape of a rectangular plate. The
upper mold 80 has a shallow and wide mold recess 81 extending in a
longitudinal direction thereof formed on a lower surface thereof.
The upper mold 80 also has six lug mold recesses 86 formed
therethrough from top to bottom. The lug mold recess 86 has a shape
corresponding to that of the tread lug 26.
[0052] The steel belt 21 is passed through the hollow lower mold 70
and a part of the steel belt 21 is placed on the upper surface of
the lower mold 70. At that time, the mold projections 74a of the
lower mold 70 are fitted into the engagement holes 21a of the steel
belt 21, thereby positioning the steel belt 21.
[0053] With the steel belt 21 positioned in the above described
manner, a raw rubber sheet (elastic material, not shown) containing
a vulcanizing agent and of a predetermined length is placed on the
upper surface of the molding section 72 of the lower mold 70.
[0054] Then the upper mold 80 is lowered to press the raw rubber
sheet and the molds 70, 80 are heated, thereby
vulcanization-bonding (vulcanization-molding) a part 22' of the
belt main body 22 (a part divided in a circumferential direction of
the belt main body 22 to be formed to be endless) to the outer
periphery of the steel belt 21 as shown in FIG. 9. It is preferable
that primer (adhesive) is applied to an outer peripheral surface of
the steel belt 21 beforehand to enhance strength of adhesion
between the part 22' of the belt main body 22 and the steel belt
21.
[0055] At the time of the molding, a part of the base part 23 is
molded with the mold recess 81, a part of the shielding brim 24 is
molded with the auxiliary mold recess 73, the escape recess 23 is
molded by allowing the mold projection 74a to press into the rubber
material and the tread lug 26 is molded by allowing the rubber
material to enter the lug mold recess 86. A part of the rubber
material protruded from an upper opening of the lug mold recess 86
is removed with a spatula, etc.
[0056] After the molding is done as described above, the upper mold
80 is lifted. Then as shown in FIG. 10, the steel belt 21 is peeled
off the lower mold 70. Since the molding of the rubber as described
above involves contraction, the mold projection 74a is attached
strongly to the rubber, and therefore the mold pin 74 is removed
from the lower mold 70 together with the steel belt 21 and the part
22' of the belt main body 22.
[0057] Next, the mold pin 74 is removed from the steel belt 21 and
the part 22' of the belt main body 22 as shown in FIG. 11. Since
the mold pin 74 is separate from the lower mold 70, the mold pin 74
can be easily detached from the escape recess 23a of the part 22'.
The productivity is improved compared to a case where mold
projections are integrally formed with the lower mold.
[0058] Next, a new part of the steel belt 21 is positioned on the
lower mold 70, the new part adjoining the part to which the part
22' of the belt main body 22 is vulcanization-bonded, by moving the
steel belt 21 in a circumferential direction, and another part 22'
of the belt main body 22 is molded in the foregoing way. By
repeating the procedure, the belt main body 22 can be attached to
the entire periphery of the steel belt 21. The part 22' of the belt
main body 22 newly molded is made continuous to the previously
molded part 22', thereby making the adjoining parts 22' of the belt
main body 22 substantially integral with each other. According to
this method, the crawler belt 20 including the shielding brim 24
and the tread lug 26 can be manufactured inexpensively by using the
lower mold 70 and the upper mold 80, both of simple construction,
without using a split mold.
[0059] Other embodiments of the present invention are described
below referring to FIGS. 12to 17. Same numbers are used for the
components corresponding to those of the first embodiment and a
detailed description thereof is omitted.
[0060] In a second embodiment as shown in FIG. 12, an outer
peripheral surface of the wheel 10 is a generally-cylindrical
surface. To be more specific, the outer edge of the cross section
of the wheel has a crowned shape of a large radius of curvature
with a central part elevated from opposite ends. In other words,
outer diameter of the wheel 10 is gradually reduced as it goes from
a center toward opposite ends in a width direction. Although
exaggerated in the drawings, the difference between the diameters
at the center and at the both ends of the wheel 10 is, in fact, not
substantial: the diameter at the center is 100 millimeters and the
diameter at the both ends is smaller than that by 0.3 millimeters
in the wheel 10 having a width of 30 millimeters in this
embodiment.
[0061] A third embodiment as shown in FIG. 13is identical to the
second embodiment except the following: the steel belt 21 is
embedded in the base part 23 of the belt main body 22 and a thin
rubber layer 29 is formed on an inner periphery of the steel belt
21. The rubber layer 29 has an inner peripheral surface
corresponding to the outer peripheral surface of the wheel 10. When
the wheel 10 is made of metal, the rubber layer 29 serves to
prevent abrasion caused by metal-to-metal contact between the steel
belt 21 and the wheel 10.
[0062] In a fourth embodiment as shown in FIGS. 14 to 16, the wheel
10 is made of resin, etc. and its outer peripheral surface is a
cylindrical surface. Engagement pins 12 made of metal are embedded
and arranged at even intervals in a circumferential direction at a
center in the width direction of the outer peripheral surface of
the wheel 10. A head part of the engagement pin 12 having a
semi-spherical shape projects from the outer peripheral surface of
the wheel 10 and is provided as an engagement projection 12a.
[0063] A shielding brim 24' is formed continuously all around
periphery of the belt main body 22 and projects in an oblique
direction from an outer peripheral surface of the base part 23. The
shielding brim 24' has a tapered cross-section and is easy to be
elastically deformed.
[0064] As shown in FIG. 16, the side plate 30 comprises a metal
plate 31 and a pair of seal members 32. As shown in FIG. 15, the
metal plate 31 has a front and rear end edges 31a, each having a
semi-circular shape corresponding to a shape of a peripheral edge
of the front and rear wheels 10, respectively. The front and rear
end edges 31a are, as shown in FIG. 15, cut away from inside to be
reduced in thickness.
[0065] As shown in FIG. 16, the seal member 32 is detachably
attached to an upper and lower parts of the peripheral edges of the
metal plate 31, the upper and lower parts having a linear shape. To
be more specific, the seal member 32 is made of rubber material
having smaller elastic coefficient than the belt main body 22 of
the crawler belt 20 to be described later. The seal member 32 is
attached to a bracket 33 having a linear shape with a L-shaped
cross section by vulcanization bonding, etc. and the bracket 33 is
removably fixed to upper and lower parts of the peripheral edge of
the side plate 30 with a screw 34. The seal member 32 includes a
thin raised wall 32a.
[0066] In the part of the crawler belt 20 which is placed around
the wheels 10 in the front and rear, the edge of the shielding brim
24 contacts the end edges 31a in the front and rear of the side
plate 30. In the other part of the crawler belt 20 which is placed
between the wheels 10 in the front and rear, the edge of the
shielding brim 24' contacts the raised wall 32a of the seal member
32. As a result, the inner space surrounded by the crawler belt 20
and the pair of side plates 30 is sealed, thereby preventing
foreign substances such as water, sands and dust from entering into
the inner space.
[0067] In the part of the crawler belt 20 which is placed around
half of the periphery of the wheels 10, the crawler belt 20 is
bent, and therefore, the shielding brim 24' is warped away from the
end edge 31a of the side plate 30. But the edge of the shielding
brim 24' can contact the end edge 31a securely despite the warping
because the edge of the shielding brim 24' is elastically deformed
as it contacts the end edge 31a of the side plate 30. When the
shielding brim 24' of the crawler belt 20 contacts the seal member
32 at the upper and lower parts of the peripheral edge of the side
plate 30, the seal member 32 is deformed more greatly than the
shielding brim 24' because the seal member 32 has smaller elastic
coefficient and is thinner than the shielding brim 24'. This
permits the seal member 32 and the shielding brim 24' to be
maintained in contact with each other even when the crawler belt 20
flaps in an area not restrained by the wheels 10 because the seal
member 32 is deformed following the flapping of the belt 20. The
seal member 32 is coated with teflon.RTM., etc., which serves to
reduce friction between the seal member 32 and the shielding brim
24'.
[0068] The lower mold 70 and the upper mold 80 as shown in FIG.
17are used to mold the crawler belt 20 according to the fourth
embodiment of the present invention. In this embodiment, a pair of
auxiliary mold recesses 82 having a linear shape are formed along
opposite sides of the mold recess 81 of the upper mold 80. The
auxiliary mold recess 82 has a cross-section corresponding to the
shield brim 24'. The molds 70 and 80 are used in the same manner as
in the first embodiment as described above.
[0069] The present invention is not limited to the above
embodiments, but various modifications can be made without
departing from the scope of the invention. For example, the pair of
crawler units may be driven by both of front and rear wheels.
[0070] Another wheel may be deployed between the wheels in the
front and rear.
[0071] A trailing wheel may not be engaged with the crawler belt as
far as it restricts movements of the crawler belt in the width
direction.
[0072] The tread lug 26 may have a planer shape of a wave being
bent at a plurality of points.
[0073] The tread lug 26 according to the first and second
embodiments may not have a trapezoidal longitudinal section but may
be formed with a uniform thickness.
[0074] Two rows of short helical engagement projections running in
different directions (double helical) may be formed on the wheel 10
and engagement holes corresponding to the helical engagement
projections may be formed in the high-tensile-strength belt so that
the crawler belt is surely prevented from meandering.
[0075] The entire periphery of the belt main body may be molded at
one time by insert injection molding, etc.
[0076] The actuator may not be an electric motor but a hydraulic
motor or an engine.
[0077] Application of the crawler unit according to the present
invention is not limited to the rescue robots. It may be applied to
other light weight robots such as those used for cleaning hospitals
or may be applied to light construction machines other than
robots.
BRIEF DESCRIPTION OF DRAWINGS
[0078] FIG. 1is a perspective view of a crawler structure of a
robot having a pair of left and right crawler units according to a
first embodiment of the present invention.
[0079] FIG. 2is a side view of the crawler unit.
[0080] FIG. 3is a longitudinal sectional view of a crawler belt
used in the crawler unit with a thickness of a steel belt
exaggerated.
[0081] FIG. 4is a longitudinal sectional view of the crawler belt
in a state of being placed around a wheel.
[0082] FIG. 5is a side view of the crawler belt.
[0083] FIG. 6is a plan view of the crawler belt.
[0084] FIG. 7is a schematic view of tread lugs of the crawler belt
as they are gripping rubble.
[0085] FIG. 8is a perspective view of equipment used for
manufacturing the crawler belt.
[0086] FIG. 9is an enlarged longitudinal view of a main part of the
equipment showing a belt main body of the crawler belt being
molded.
[0087] FIG. 10is an enlarged longitudinal view of a main part of
the equipment showing a molded part of the belt main body and the
steel belt being removed from a lower mold.
[0088] FIG. 11is an enlarged longitudinal view of a main part of
the equipment showing a mold pin being removed form a molded part
of the belt main body and the steel belt.
[0089] FIG. 12is a longitudinal sectional view of a crawler unit
according to a second embodiment of the present invention.
[0090] FIG. 13is a longitudinal sectional view of a crawler unit
according to a third embodiment of the present invention.
[0091] FIG. 14is an enlarged longitudinal sectional view of a
crawler belt according to a fourth embodiment of the present
invention.
[0092] FIG. 15is a longitudinal sectional view showing a seal
structure between the crawler belt and an end edge of a side plate
according to the fourth embodiment of the present invention.
[0093] FIG. 16is a longitudinal sectional view showing a seal
structure between the crawler belt and a middle part of the side
plate according to the fourth embodiment of the present
invention.
[0094] FIG. 17is a perspective view of equipment used for
manufacturing the crawler belt according to the fourth embodiment
of the present invention.
DESCRIPTION OF REFERENCE NUMERALS
[0095] 2 crawler unit [0096] 10 wheel [0097] 12a engagement
projection [0098] 20 crawler belt [0099] 21 steel belt (thin metal
belt, high-tensile-strength belt) [0100] 22 belt main body [0101]
23 base part [0102] 24, 24' shielding brim [0103] 26 tread lug
[0104] 30 side plate [0105] 70 lower mold (first mold) [0106] 74
mold pin [0107] 74a mold projection [0108] 80 upper mold (second
mold) [0109] 86 lug mold hole (lug mold recess)
* * * * *