U.S. patent application number 17/299010 was filed with the patent office on 2022-02-17 for cutting edge for work machine, blade for work machine, and work machine.
This patent application is currently assigned to KOMATSU LTD.. The applicant listed for this patent is KOMATSU LTD.. Invention is credited to Yohei HASHIMOTO, Akira HOSOKAWA, Takeshi KAMIMAE, Shintaro KOBAYASHI, Shu TAKEDA.
Application Number | 20220049455 17/299010 |
Document ID | / |
Family ID | 1000005983712 |
Filed Date | 2022-02-17 |
United States Patent
Application |
20220049455 |
Kind Code |
A1 |
KOBAYASHI; Shintaro ; et
al. |
February 17, 2022 |
CUTTING EDGE FOR WORK MACHINE, BLADE FOR WORK MACHINE, AND WORK
MACHINE
Abstract
A cutting edge has an attachment portion and a wear portion. The
attachment portion has a first thickness, which is a maximum value
of a thickness between a first surface and a second surface. The
wear portion includes a first portion having a third surface
contiguous to the first surface and a fourth surface facing away
from the third surface, and having a second thickness between the
third surface and the fourth surface and smaller than the first
thickness, and an edge located opposite to the attachment portion.
The second portion extends on the first portion from a portion of
the fourth surface toward a side opposite to the third surface, and
also extends on the first portion from the edge toward the
attachment portion.
Inventors: |
KOBAYASHI; Shintaro;
(Minato-ku, Tokyo, JP) ; KAMIMAE; Takeshi;
(Minato-ku, Tokyo, JP) ; TAKEDA; Shu; (Minato-ku,
Tokyo, JP) ; HOSOKAWA; Akira; (Kanazawa-shi,
Ishikawa, JP) ; HASHIMOTO; Yohei; (Kanazawa-shi,
Ishikawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KOMATSU LTD. |
Minato-ku, Tokyo |
|
JP |
|
|
Assignee: |
KOMATSU LTD.
Minato-ku, Tokyo
JP
|
Family ID: |
1000005983712 |
Appl. No.: |
17/299010 |
Filed: |
January 29, 2020 |
PCT Filed: |
January 29, 2020 |
PCT NO: |
PCT/JP2020/003082 |
371 Date: |
June 2, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E02F 3/8152
20130101 |
International
Class: |
E02F 3/815 20060101
E02F003/815 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 28, 2019 |
JP |
2019-063736 |
Claims
1. A cutting edge for a work machine attached to the work machine,
comprising: an attachment portion having a first surface and a
second surface facing away from each other, and a first thickness
being a maximum value of a thickness between the first surface and
the second surface; and a wear portion integrated with the
attachment portion, the wear portion having a first portion having
a third surface contiguous to the first surface and a fourth
surface facing away from the third surface, and having a second
thickness between the third surface and the fourth surface, the
second thickness being smaller than the first thickness, and an
edge located opposite to the attachment portion, and a second
portion extending from a portion of the fourth surface of the first
portion toward a side opposite to the third surface, and extending
from the edge of the first portion toward the attachment
portion.
2. The cutting edge for a work machine according to claim 1,
wherein the attachment portion has a through hole, and the through
hole has a diameter-expanded portion connected to the first
surface.
3. The cutting edge for a work machine according to claim 1,
wherein the second thickness is fixed from the edge of the first
portion to an end of the first portion located closer to the
attachment portion.
4. The cutting edge for a work machine according to claim 1,
wherein a ratio of the second thickness to the first thickness is
50% or less.
5. The cutting edge for a work machine according to claim 1,
further comprising an intermediate portion located between the
attachment portion and the wear portion, wherein the intermediate
portion has a thickness decreasing from the attachment portion
toward the wear portion.
6. The cutting edge for a work machine according to claim 1,
wherein the second portion is a reinforcing rib.
7. The cutting edge for a work machine according to claim 1,
wherein the second portion configures a recess recessed toward the
fourth surface of the first portion with respect to the third
surface of the first portion.
8. The cutting edge for a work machine according to claim 1,
wherein the second portion reaches the attachment portion.
9. The cutting edge for a work machine according to claim 1,
wherein the second portion has a first end portion connected to the
fourth surface and a second end portion opposite to the first end
portion, and the second end portion has a portion located opposite
to the fourth surface with respect to the second surface of the
attachment portion.
10. A blade for a work machine comprising: the cutting edge for the
work machine according to claim 1; and a blade body to which the
cutting edge is attached.
11. A work machine comprising: the blade for the work machine
according to claim 10; and a body of the work machine to which the
blade for the work machine is attached.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a cutting edge for a work
machine, a blade for a work machine, and a work machine.
BACKGROUND ART
[0002] There is a demand for work machines such as a motor grader
to work more efficiently. Working more efficiently includes better
performance for excavation, a cutting edge enhanced in durability,
and the like. A cutting edge that addresses this issue is disclosed
for example in U.S. Pat. No. 3,021,626 (PTL 1).
[0003] The cutting edge disclosed in PTL 1 has a front surface with
a raised portion and a rear surface with a reinforcing rib.
CITATION LIST
Patent Literature
[0004] PTL 1: U.S. Pat. No. 3,021,626
SUMMARY OF INVENTION
Technical Problem
[0005] The cutting edge disclosed in PTL 1, however, has an edge
with low rigidity and is thus difficult to be enhanced in
durability.
[0006] An object of the present disclosure is to provide a cutting
edge for a work machine, a blade for a work machine, and a work
machine, that can provide satisfactory performance for excavation
and be easily improved in durability.
Solution to Problem
[0007] The presently disclosed cutting edge for a work machine is a
cutting edge for a work machine attached to the work machine, and
including an attachment portion and a wear portion. The attachment
portion has a first surface and a second surface facing away from
each other, and a first thickness being a maximum value of a
thickness between the first surface and the second surface. The
wear portion is integrated with the attachment portion. The wear
portion has a first portion and a second portion. The first portion
has a third surface continuous to the first surface and a fourth
surface facing away from the third surface, and has a second
thickness between the third surface and the fourth surface, and an
edge located opposite to the attachment portion. The second
thickness is smaller than the first thickness. The second portion
extends from a portion of the fourth surface of the first portion
toward a side opposite to the third surface, and extends from the
edge of the first portion toward the attachment portion.
Advantageous Effects of Invention
[0008] According to the present disclosure, a cutting edge for a
work machine, a blade for a work machine, and a work machine, that
provides satisfactory performance for excavation and is easily
improved in durability can be implemented.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is a perspective view showing a configuration of a
motor grader as a work machine according to a first embodiment.
[0010] FIG. 2 is a side view showing a configuration of a blade for
a work machine included in the work machine shown in FIG. 1.
[0011] FIG. 3 is a front perspective view of a cutting edge
included in the FIG. 2 blade for the work machine.
[0012] FIG. 4 is a rear perspective view of the cutting edge
included in the FIG. 2 blade for the work machine.
[0013] FIG. 5 is a cross section taken along a line V-V indicated
in FIG. 4.
[0014] FIG. 6 is a cross section taken along a line VI-VI indicated
in FIG. 5.
[0015] FIG. 7 is a front, partial perspective view of a
configuration of a cutting edge included in a work machine
according to a second embodiment.
[0016] FIG. 8 is a rear, partial perspective view of the
configuration of the cutting edge included in the work machine
according to the second embodiment.
[0017] FIG. 9 is a cross section taken along a line IX-IX indicated
in FIG. 8.
[0018] FIG. 10 is a cross section taken along a line X-X indicated
in FIG. 8.
DESCRIPTION OF EMBODIMENTS
[0019] Hereinafter, embodiments of the present disclosure will be
described in detail with reference to the drawings. In the
specification and drawings, identical or corresponding components
are identically denoted and will not be described redundantly. In
the drawings, configuration may be omitted or simplified for
convenience of description. Each embodiment and each variation may
at least partially be combined together.
First Embodiment
Configuration of Work Machine
[0020] Initially, a configuration of a motor grader which is an
example of a work machine to which the concept of the present
disclosure is applicable, will be described. Note that the present
disclosure is also applicable to other work machines than the motor
grader having a blade.
[0021] FIG. 1 is a perspective view schematically showing a
configuration of a motor grader according to a first embodiment. As
shown in FIG. 1, a motor grader 10 according to the present
embodiment mainly includes a work implement 1, a body frame 2, a
cab (or driver's compartment) 3, and traveling wheels 4 and 5.
Motor grader 10 includes components such as an engine disposed in
an engine compartment 2aa. Work implement 1 for example includes a
blade 11. Motor grader 10 can perform operations such as a land
grading operation, a snow plowing operation, a light cutting
operation, and a material mixing operation by blade 11.
[0022] In the following description for the drawings, a direction
in which motor grader 10 travels straight forward/backward is
referred to as a forward/backward direction of motor grader 10. In
the forward/backward direction of motor grader 10, a side on which
front wheel 4 is located with respect to work implement 1 is
defined as a forward direction. In the forward/backward direction
of motor grader 10, a side on which rear wheel 5 is located with
respect to work implement 1 is defined as a backward direction. A
rightward/leftward direction of motor grader 10 is a direction
orthogonal to the forward/backward direction in a plan view. When
looking in the forward direction, a right side and a left side in
the rightward/leftward direction are a rightward direction and a
rightward direction, respectively. An upward/downward direction of
motor grader 10 is a direction orthogonal to a plane defined by the
forward/backward direction and the rightward/leftward direction. In
the upward/downward direction, a side on which the ground is
present is a downward side, and a side on which the sky is present
is an upward side.
[0023] Body frame 2 includes a rear frame 2a and a front frame 2b.
Rear frame 2a supports an exterior cover 2ab and components such as
the engine disposed in engine compartment 2aa. Exterior cover 2ab
covers engine compartment 2aa. For example, four rear wheels 5 are
attached to rear frame 2a. Four rear wheels 5 can each be rotatably
driven by a driving force received from the engine.
[0024] Front frame 2b has a base end portion coupled to rear frame
2a and a foremost end portion opposite to the base end portion.
Front frame 2b has the base end portion coupled to a foremost end
portion of rear frame 2a by a center pin extending in the
upward/downward direction.
[0025] An articulation cylinder (not shown) is attached between
front frame 2b and rear frame 2a. Front frame 2b is provided
articulatably with respect to rear frame 2a as an articulation
cylinder extends and retracts.
[0026] Front frame 2b has its foremost end portion for example with
two front wheels 4 rotatably attached thereto. Front wheel 4 is
attached to front frame 2b pivotably as a steering cylinder 6
extends and retracts. Motor grader 10 can change in which direction
it proceeds by extending and retracting steering cylinder 6.
[0027] Cab 3 is mounted on front frame 2b. Inside cab 3 is provided
an operation unit (not shown) such as a handle, a transmission
lever, a lever operated to control work implement 1, a brake, an
accelerator pedal, and an inching pedal, etc. Cab 3 may be mounted
on rear frame 2a.
[0028] Work implement 1 mainly includes, for example, blade 11, a
drawbar 12, a circle 13, lift cylinders 14 and 15, a drawbar shift
cylinder 16, a blade shift cylinder 17, and a hydraulic motor
18.
[0029] Drawbar 12 is disposed below front frame 2b. Drawbar 12 has
a front end portion coupled with the foremost end portion of front
frame 2b via a ball bearing. Drawbar 12 has the front end portion
attached to the foremost end portion of front frame 2b so as to be
capable of swinging.
[0030] Drawbar 12 has a rear end portion supported by front frame
2b via a pair of lift cylinders 14 and 15. As the pair of lift
cylinders 14 and 15 extends and retracts, drawbar 12 can have the
rear end portion moved upward/downward with respect to front frame
2b. Further, as the paired lift cylinders 14 and 15 differently
extend and retract, drawbar 12 can swing about an axis extending in
the forward/backward direction.
[0031] Circle 13 is disposed below drawbar 12. Circle 13 is
pivotably (rotatably) attached to the rear end portion of drawbar
12. Circle 13 can be driven by hydraulic motor 18 to pivot both
clockwise and counterclockwise with respect to drawbar 12, as seen
above work machine 10.
[0032] Blade 11 is supported by circle 13. As circle 13 is driven
to rotate, blade 11 has a blade angle adjusted. The blade angle is
a tilt angle of blade 11 with respect to the forward/backward
direction of motor grader 10, as seen at a point above work machine
10 (in plan view).
[0033] Blade 11 is disposed between front wheel 4 and rear wheel 5.
Blade shift cylinder 17 is attached to circle 13 and blade 11 and
is disposed longitudinally of blade 11. Blade 11 is movable by
blade shift cylinder 17 in the rightward/leftward direction with
respect to circle 13.
[0034] A tilt cylinder (not shown) is attached to circle 13 and
blade 11. As the tilt cylinder extends and retracts, blade 11 can
swing with respect to circle 13 about an axis extending
longitudinally of blade 11 to have a tilt angle changed with
respect to a direction in which blade 11 proceeds.
[0035] Blade 11 is thus attached to the body of the work machine
composed of traveling wheels 4 and 5, body frame 2, and cab 3.
Blade 11 is configured to be capable, via drawbar 12 and circle 13,
of: moving up and down with respect to the body of the work
machine; swinging about an axis extending in a direction in which
work machine 10 proceeds; changing a tilt angle with respect to the
forward/backward direction; moving in the rightward/leftward
direction; and swinging about an axis extending longitudinally of
blade 11.
Configuration of Blade 11
[0036] Hereinafter, a configuration of blade 11 included in work
machine 10 (a blade for a work machine) will be described with
reference to FIG. 2.
[0037] FIG. 2 is a side view showing a configuration of a blade for
a work machine included in the work machine shown in FIG. 1. As
shown in FIG. 2, blade 11 has a blade body 11a and a cutting edge
20. Blade body 11a has a front surface 11aa and a rear surface 11ab
facing away from each other. Blade body 11a has front surface 11 as
and rear surface 11ab each curved in a cross section of blade body
11a taken vertically (or in a direction along a shorter side of
blade 11).
[0038] Blade body 11a has rear surface flab with a pair of rails
11d attached thereto via a holding frame 11e. The pair of rails 11d
is supported by a guide bracket (not shown) slidably along blade
11. Blade 11 is attached to the body of the work machine via a
blade supporting mechanism (not shown) including the guide
bracket.
[0039] Blade body 11a has a lower end portion to which cutting edge
20 is attached. Cutting edge 20 is fixed to blade body 11a for
example with a bolt 11b and a nut 11c. Specifically, bolt 11b is
inserted from a front side into a through hole 20h of cutting edge
20 and a through hole 11f of blade body 11a, and fastened by nut
11c behind blade body 11a. Cutting edge 20 is thus fixed to blade
body 11a.
Configuration of Cutting Edge 20
[0040] Hereinafter, a configuration of cutting edge 20 included in
blade 11 will be described with reference to FIGS. 3 to 6.
[0041] FIGS. 3 and 4 are a front perspective view and a rear
perspective view, respectively, of a configuration of a cutting
edge included in the FIG. 2 blade for the work machine. FIGS. 5 and
6 are a cross section taken along a line V-V indicated in FIG. 4
and a cross section taken along a line VI-VI indicated in FIG. 5,
respectively.
[0042] As shown in FIG. 5, cutting edge 20 has an attachment
portion 21, a wear portion 22, and an intermediate portion 23.
Attachment portion 21, wear portion 22 and intermediate portion 23
are integrated together.
[0043] Attachment portion 21 has a first surface 20A and a second
surface 20B facing away from each other. First surface 20A is a
front surface of attachment portion 21, and second surface 20B is a
rear surface of attachment portion 21. Attachment portion 21 has a
thickness t1 (a first thickness), which is a maximum value of a
thickness between first surface 20A and second surface 20B.
[0044] Attachment portion 21 has first surface 20A and second
surface 20B in parallel from a bonding portion of attachment
portion 21 and intermediate portion 23 to a position 21M. A
thickness of attachment portion 21 from the bonding portion of
attachment portion 21 and intermediate portion 23 to position 21M
is thickness t1 and thus fixed.
[0045] Second surface 20B is inclined with respect to first surface
20A such that first surface 20A and second surface 20B approach
each other from position 21M toward an edge 21T. Therefore, a
thickness of attachment portion 21 from position 21M to edge 21T of
attachment portion 21 decreases from position 21M toward edge
21T.
[0046] Attachment portion 21 has a portion 20h for attachment to
blade body 11a. Portion 20h is disposed between the bonding portion
of attachment portion 21 and intermediate portion 23 and position
21M. Portion 20h is located at a portion of attachment portion 21
having maximum thickness t1.
[0047] Portion 20h for attachment to blade body 11a is for example
a through hole 20h receiving bolt 11b, as described above. Through
hole 20h penetrates through attachment portion 21 from first
surface 20A to second surface 20B. Through hole 20h has a
diameter-expanded portion 20ha expanding in diameter while
extending from second surface 20B toward first surface 20A, and a
radially fixed portion 20hb extending from diameter-expanded
portion 20ha toward second surface 20B while maintaining a
diameter. Diameter-expanded portion 20ha is for example in the form
of a truncated cone, and radially fixed portion 20hb is for example
in the form of a prism.
[0048] Wear portion 22 is located below attachment portion 21. Wear
portion 22 has a first portion 22a and a second portion 22b. Second
portion 22b is located behind first portion 22a.
[0049] First portion 22a has a third surface 20C and a fourth
surface 20D facing away from each other. Third surface 20C is a
front surface of first portion 22a, and fourth surface 20D is a
rear surface of first portion 22a. Third surface 20C is contiguous
to first surface 20A.
[0050] First portion 22a has a thickness t2 (a second thickness)
between third surface 20C and fourth surface 20D. Thickness t2 is
smaller than thickness t1 of attachment portion 21. A ratio of
thickness t2 to thickness t1 (i.e., t2/t1) is 50% or less.
[0051] First portion 22a has an edge 22T located on a side opposite
to attachment portion 21. Third surface 20C and fourth surface 20D
of first portion 22a are in parallel. Thus, first portion 22a
extends from an end portion thereof closer to attachment portion 21
to edge 22T while maintaining thickness t2. Thickness t2 is fixed
from edge 22T to a bonding portion of first portion 22a and
intermediate portion 23.
[0052] Second portion 22b extends from a portion of fourth surface
20D of first portion 22a toward a side opposite to third surface
20C. Second portion 22b extends from edge 22T of first portion 22a
toward attachment portion 21 in the upward/downward direction
(i.e., a direction along a shorter side of cutting edge 20). Second
portion 22b is in contact with fourth surface 20D of edge 22T.
Second portion 22b extends in the upward/downward direction from
edge 22T to at least a portion at which first portion 22a is
connected to intermediate portion 23, and second portion 22b is
thus connected to first portion 22a.
[0053] Second portion 22b has a first end portion 22F connected to
first portion 22a on fourth surface 20D, and a second end portion
22R facing away from first end portion 22F. Second end portion 22R
is located rearwardly of first end portion 22F.
[0054] Second end portion 22R of second portion 22b has a portion
located rearwardly of second surface 20B of attachment portion 21.
Specifically, second end portion 22R of second portion 22b at a
base portion 22b2 is located rearwardly of second surface 20B of
attachment portion 21. Second end portion 22R has a portion located
on a side opposite to fourth surface 20D with respect to second
surface 20B. Specifically, second end portion 22R at base portion
22b2 is located on a side opposite to fourth surface 20D with
respect to second surface 20B. Thus, a total t4 in thickness of
first portion 22a and base portion 22b2 of second portion 22b (see
FIG. 6) is larger than thickness t1 of attachment portion 21 (FIG.
5).
[0055] Second portion 22b has a tip portion 22b1 and base portion
22b2. Tip portion 22b1 is located below base portion 22b2. Tip
portion 22b1 is a portion extending toward attachment portion 21
from edge 22T of first portion 22a. Base portion 22b2 is a portion
connected to tip portion 22b1 and located closer to attachment
portion 21 than tip portion 22b1.
[0056] Second end portion 22R at tip portion 22b1 is inclined with
respect to fourth surface 20D so as to approach fourth surface 20D
as second end portion 22R approaches edge 22T. Second end portion
22R at base portion 22b2 is parallel to fourth surface 20D.
[0057] Intermediate portion 23 is located between attachment
portion 21 and wear portion 22. Intermediate portion 23 has a fifth
surface 20E and a sixth surface 20F facing away from each other.
Fifth surface 20E is a front surface of intermediate portion 23,
and sixth surface 20F is a rear surface of intermediate portion 23.
Fifth surface 20E is contiguous to each of first surface 20A and
third surface 20C.
[0058] Intermediate portion 23 has a thickness t3 (a third
thickness) between fifth surface 20E and sixth surface 20F.
Intermediate portion 23 has thickness t3 reduced from attachment
portion 21 toward wear portion 22. Intermediate portion 23 has
sixth surface 20F inclined with respect to fifth surface 20E so as
to approach fifth surface 20E from attachment portion 21 toward
wear portion 22. Intermediate portion 23 has sixth surface 20F so
as to form a step between second surface 20B of attachment portion
21 and fourth surface 20D of wear portion 22.
[0059] Wear portion 22 has second portion 22b connected to
intermediate portion 23 at sixth surface 20F. Second portion 22b is
connected throughout sixth surface 20F in the upward/downward
direction from a connecting portion between intermediate portion 23
and first portion 22a to a connecting portion between intermediate
portion 23 and attachment portion 21. Second portion 22b reaches
second surface 20B of attachment portion 21. Second portion 22b is
connected to a portion of second surface 20B.
[0060] First surface 20A of attachment portion 21, third surface
20C of first portion 22a, and fifth surface 20E of intermediate
portion 23 define a front surface FS of cutting edge 20.
[0061] As shown in FIG. 3, first surface 20A of attachment portion
21 and fifth surface 20E of intermediate portion 23 are
continuously connected without making a break or a step. Fifth
surface 20E of intermediate portion 23 and third surface 20C of
first portion 22a are continuously connected without making a break
or a step. Thus, front surface FS composed of first surface 20A of
attachment portion 21, fifth surface 20E of intermediate portion
23, and third surface 20C of first portion 22a configure a single
surface.
[0062] As shown in FIG. 4, cutting edge 20 has a plurality of
second portions 22b. The plurality of second portions 22b are
aligned in a longitudinal direction LD of cutting edge 20. The
plurality of second portions 22b are equally spaced in longitudinal
direction LD of cutting edge 20. The plurality of second portions
22b are disposed in parallel.
[0063] As shown in FIG. 5, front surface FS is curved in a cross
section taken in the upward/downward direction from edge 21T of
attachment portion 21 to edge 22T of first portion 22a. In this
cross section, a portion sandwiched between both edges 21T and 22T
is recessed with respect to both edges 21T and 22T.
[0064] As shown in FIG. 6, second portion 22b is a reinforcing rib
for reinforcing first portion 22a in strength. Total t4 in
thickness of first portion 22a and second portion 22b is larger
than thickness t2 of first portion 22a.
[0065] Thickness t2 of first portion 22a is equal to or smaller
than a thickness of second portion 22b (i.e., t4-t2). A ratio of
thickness t2 of first portion 22a to thickness (t4-t2) of second
portion 22b (i.e., t2/(t4-t2)) is 50% or less.
[0066] A pitch P of the plurality of second portions 22b has a
dimension for example of five times a width W of second portion
22b.
[0067] Front surface FS extends linearly in the cross section taken
in longitudinal direction LD shown in FIG. 6. First surface 20A of
attachment portion 21, third surface 20C of first portion 22a, and
fifth surface 20E of intermediate portion 23 each extend linearly
in the cross section taken in longitudinal direction LD shown in
FIG. 6.
Effect
[0068] The present embodiment has an effect, as will be described
below:
[0069] According to the present embodiment, as shown in FIG. 5, a
second thickness t2 of first portion 22a is smaller than a first
thickness t1 of attachment portion 21. This helps first portion 22a
to dig into a target of excavation. Satisfactory performance for
excavation can thus be provided.
[0070] The present inventors conducted a simulation of a phenomenon
of excavation, and as a result have found that contact stress (=a
wear rate) is hardly affected even when a contact area between
cutting edge 20 and a target of excavation (e.g., the ground) is
increased. Therefore, by reducing second thickness t2 of first
portion 22a, an area of contact with the target of excavation can
be reduced, and excavation resistance (i.e., reaction force with
respect to a fixed cut amount) can be reduced while a wear rate is
held equally. This allows reduced force to be applied to press
blade 11 against the target of excavation to excavate it, and thus
improves fuel efficiency.
[0071] Further, as excavation resistance is reduced, blade 11 can
be increased in width in the rightward/leftward direction when
cutting edge 20 is pressed against the target of excavation with a
given force. As a result, an increased amount of work and hence
better performance for excavation can be achieved.
[0072] Further, second portion 22b extends from a portion of fourth
surface 20D of first portion 22a toward a side opposite to third
surface 20C. Second portion 22b thus reinforces first portion 22a
in strength. This enhances cutting edge 20 in rigidity.
[0073] Further, second portion 22b is also disposed at edge 22T of
first portion 22a. This allows cutting edge 20 to have an edge
(i.e., edge 22T of first portion 22a) enhanced in rigidity, and
thus enhances cutting edge 20 in rigidity.
[0074] Furthermore, according to the present embodiment, it is
unnecessary to attach a high-hardness bit to cutting edge 20 or add
a wear-resistant alloy thereto. This allows cutting edge 20 to be
manufactured with a reduced cost.
[0075] Further, in the present embodiment, as shown in FIG. 5,
first portion 22a has second thickness t2 fixed from edge 22T of
first portion 22a to an end portion of first portion 22a located
closer to attachment portion 21. Thus, even when first portion 22a
has edge 22T worn through excavation, performance for excavation
equivalent to that when its use is started can be obtained.
Further, as first portion 22a has second thickness t2 fixed,
resistance when cutting edge 20 digs into a target of excavation
can be held low.
[0076] Further, in the present embodiment, as shown in FIG. 5, a
ratio of second thickness t2 of first portion 22a to first
thickness t1 of attachment portion 21 (i.e., t2/t1) is 50% or less.
First portion 22a having thus reduced second thickness t2 allows
further better performance for excavation.
[0077] Further, in the present embodiment, as shown in FIG. 5,
intermediate portion 23 has thickness t3 reduced from attachment
portion 21 toward wear portion 22. As intermediate portion 23 has
thickness t3 thus gradually changed, there is no portion with
abrupt variation in thickness. A portion with abrupt variation in
thickness is likely to experience stress concentration during
excavation, and is thus damageable. In the present embodiment,
there is no such damageable portion.
[0078] Further, in the present embodiment, as shown in FIG. 5,
second portion 22b is a reinforcing rib. Thus, first portion 22a is
reinforced by second portion 22b and thus enhanced in rigidity.
[0079] Further, in the present embodiment, as shown in FIG. 5,
second portion 22b reaches attachment portion 21. Second portion
22b extending in the upward/downward direction throughout first
portion 22a having small thickness t2 can provide further enhanced
rigidity.
[0080] Further, in the present embodiment, as shown in FIG. 5,
second portion 22b has second end portion 22R having a portion
located on a side opposite to fourth surface 20D with respect to
second surface 20B of attachment portion 21. Second portion 22b can
thus have a thickness (t4-t2) increased to provide further enhanced
rigidity.
[0081] Further, if cutting edge 20 has front surface FS with
unevenness in a cross section taken in longitudinal direction LD,
cutting edge 20 is less likely to cause soil to flow in
longitudinal direction LD thereof.
[0082] In the present embodiment, in contrast, as shown in FIG. 3,
cutting edge 20 has front surface FS composed of a single surface
(a curved face). Further, as shown in FIG. 6, cutting edge 20 has
front surface FS linearly or in a single curved shape in a cross
section taken in longitudinal direction LD. This facilitates
ejecting soil and the like outside cutting edge 20 in longitudinal
direction LD, and thus allows a land grading operation to be
performed more efficiently.
Second Embodiment
Configuration of Cutting Edge 20
[0083] Hereinafter, a configuration of a cutting edge in a second
embodiment will be described with reference to FIGS. 7 to 10.
[0084] FIGS. 7 and 8 are a front perspective view and a rear
perspective view, respectively, of a configuration of a cutting
edge included in a work machine according to the second embodiment.
FIGS. 9 and 10 are a cross section taken along a line IX-IX
indicated in FIG. 8 and a cross section taken along a line X-X
indicated in FIG. 8, respectively.
[0085] As shown in FIG. 7, cutting edge 20 of the present
embodiment is different from the configuration of the first
embodiment in that cutting edge 20 has front surface FS provided
with a recess 20G.
[0086] A plurality of recesses 20G are aligned in longitudinal
direction LD of cutting edge 20. The plurality of recesses 20G are
provided at equal intervals for example. Each recess 20G extends
from edge 22T of first portion 22a toward edge 21T of attachment
portion 21.
[0087] As shown in FIG. 8, recess 20G is defined by second portion
22b. Second portion 22b has an inclined portion 22ba, a rear end
portion 22bb, and a pair of side portions 22bc.
[0088] Paired side portion 22bc each extend from a portion of
fourth surface 20D of first portion 22a toward a side opposite to
third surface 20C. Paired side portions 22bc are spaced from each
other. Paired side portions 22bc extend in parallel, for
example.
[0089] Inclined portion 22ba and rear end portion 22bb are disposed
so as to bridge paired side portions 22bc. Paired side portion 22bc
each connect fourth surface 20D of first portion 22a and a side end
portion of inclined portion 22ba. Further, paired side portions
22bc each connect fourth surface 20D of first portion 22a and a
side end portion of rear end portion 22bb.
[0090] As shown in FIG. 9, inclined portion 22ba extends toward
attachment portion 21 from a position corresponding to edge 22T of
first portion 22a. Inclined portion 22ba is inclined with respect
to front surface FS of cutting edge 20 so as to approach front
surface FS of cutting edge 20 as inclined portion 22ba approaches
the position corresponding to edge 22T of first portion 22a.
[0091] Rear end portion 22bb is connected to an end portion of
inclined portion 22ba that is closer to attachment portion 21. Rear
end portion 22bb extends toward attachment portion 21 from the end
portion of inclined portion 22ba that is closer to attachment
portion 21. Rear end portion 22bb reaches attachment portion 21
beyond intermediate portion 23. Rear end portion 22bb is connected
to attachment portion 21. A portion of rear end portion 22bb that
extends toward attachment portion 21 from a portion of rear end
portion 22bb connected to inclined portion 22ba extends parallel to
front surface FS of cutting edge 20.
[0092] Inclined portion 22ba and rear end portion 22bb each have a
front surface forming a bottom surface of recess 20G. Paired side
portions 22bc have their respective side surfaces to define those
of recess 20G.
[0093] Second end portion 22R at rear end portion 22bb on a side
opposite to front surface FS is located farther from front surface
FS than second surface 20B of attachment portion 21. A distance t4
from front surface FS to second end portion 22R at rear end portion
22bb is larger than thickness t1 of attachment portion 21.
[0094] Note that the configuration of a cross section taken along
line V-V indicated in FIG. 8 is the same as the configuration of
the first embodiment shown in FIG. 5.
[0095] As shown in FIG. 10, side portion 22bc of second portion 22b
functions as a reinforcing rib for reinforcing first portion 22a in
strength.
[0096] Distance t4 from front surface FS to second end portion 22R
at rear end portion 22bb is larger than a sum of thickness t2 of
first portion 22a and a thickness t5 of rear end portion 22bb.
Recess 20G has a depth D larger than thickness t2 of first portion
22a.
[0097] Note that the configuration of cutting edge 20 of the
present embodiment other than the above is substantially the same
as that of the first embodiment, and accordingly, any component
identical to that of the first embodiment is identically denoted
and will not be described redundantly.
Effect
[0098] According to the present embodiment, as shown in FIG. 5,
second thickness t2 of first portion 22a is smaller than first
thickness t1 of attachment portion 21. This, as well as the first
embodiment, enables satisfactory performance for excavation and
allows reduced force to be applied to press blade 11 against a
target of excavation to excavate it.
[0099] Further, second portion 22b has side portion 22bc extending
from a portion of fourth surface 20D of first portion 22a toward a
side opposite to third surface 20C. Side portion 22bc reinforces
first portion 22a in strength. This enhances cutting edge 20 in
rigidity.
[0100] Further, side portion 22bc is also disposed at edge 22T of
first portion 22a. This allows cutting edge 20 to have an edge
(i.e., edge 22T of first portion 22a) enhanced in rigidity, and
thus enhances cutting edge 20 in rigidity.
[0101] The presently disclosed embodiments are to be considered as
illustrative in any respect and not restrictive. The scope of the
present invention is not indicated by the above description but by
the scope of the claims, and is intended to include meanings
equivalent to the scope of the claims and any modifications within
the scope.
REFERENCE SIGNS LIST
[0102] 1 work implement, 2 body frame, 2F front end, 2a rear frame,
2aa engine compartment, 2ab exterior cover, 2b front frame, 3 cab,
4 front wheel, 5 rear wheel, 6 steering cylinder, 10 work machine
(motor grader), 11 blade, 11a blade body, 11aa, FS front surface,
11ab rear surface, 11b bolt, 11c nut, 11d rail, 11e holding frame,
11f, 20h through hole, 12 drawbar, 13 circle, 14, 15 lift cylinder,
16 drawbar shift cylinder, 17 blade shift cylinder, 18 hydraulic
motor, 20 cutting edge, 20A first surface, 20B second surface, 20C
third surface, 20D fourth surface, 20E fifth surface, 20F sixth
surface, 20h portion, 20ha diameter-expanded portion, 20hb radially
fixed portion, 21 attachment portion, 21M intermediate position,
21T, 22T edge, 22 wear portion, 22F first end portion, 22R second
end portion, 22a first portion, 22b second portion, 22b1 tip
portion, 22b2 base portion, 22ba inclined portion, 22bb rear end
portion, 22bc side portion, 23 intermediate portion.
* * * * *