Shearing machine for steel material

A shearing machine is provided. The machine comprises a lower stationary jaw detachably mounted on one end of an arm of a working machine for rotatable and tiltable movement, the lower stationary jaw having attached thereto a plurality of shearing blades, an upper movable jaw having a plurality of shearing blades adapted to be opened and closed in a scissors-like manner relative to the shearing blades of the lower stationary jaw so as to shear an article to be sheared, and a hydraulic cylinder for pivotally moving the upper movable jaw. The forward-end shearing blade of the lower stationary jaw and the forward-end shearing blade of the upper movable jaw are arranged in a staggered or angled manner relative to their respective adjacent shearing blades of the lower and upper jaws, respectively, so that the forward-end shearing blades of the lower and upper jaws, respectively, may be first engaged with each other, when moved in a vertical direction.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a shearing machine mounted on a tip of an arm of 
a working machine, such as a power shovel, for shearing various kinds of 
steel material. 2. Statement of the Prior Art 
When dismantling or destroying reinforcing bars, buildings of a reinforced 
concrete construction, scraps of steel, articles or chemical machinery of 
steel alloy, a steel material shearing machine is usually used, the 
machine being attached to one end of an arm of a working machine, such as 
a power shovel. An example of such shearing machines is disclosed in U.S. 
Pat. No. 4,519,135 and shown in FIG. 8. The shearing machine disclosed in 
the Patent includes a lower stationary jaw 2 integrally attached to one 
end of an arm 1 of a power shovel. An upper movable jaw 3 is connected to 
the lower stationary jaw via a support shaft 4 so that it may be opened 
and closed vertically in a scissors-like manner. The upper movable jaw 3 
may be opened and closed by means of a plurality of hydraulic cylinders 5 
mounted on the arm 1. In this manner, the movable jaw 3 is moved relative 
to the lower stationary jaw so as to shear or cut a steel material clamped 
therebetween. The lower stationary jaw 2 and upper movable jaw cooperate, 
in their engaged position, to define a central concave area, so as to 
prevent a steel material clamped therebetween from slipping off in a 
forward direction. 
The opposite surface of the lower stationary jaw 2 and upper movable jaw 3 
cooperate to form a recess 8 defined by side plates 6, 6 and a forward-end 
connection plate 7. Pressure plates 9 and 10 are disposed at a forward end 
of a recess 8 in the lower stationary jaw 2 and at a forward end of the 
upper movable jaw 3, respectively. In this manner, the pressure plate 10 
on the upper movable jaw 3, when actuated, is inserted into the recess 8 
in the lower stationary jaw 2 and abuts with the pressure plate 9, so as 
to prevent the upper movable jaw 3 from moving sideways away from the 
lower stationary jaw. The lower stationary jaw 2 and upper movable jaw 3 
include attached thereto a plurality of lower shearing blades 11 and upper 
shearing blades 12 adapted to be inter-engaged relative to one another. 
Another example of such a shearing machine is disclosed in Japanese Patent 
Publication [KOKOKU] No. 56-49273. Although not shown in the drawings, a 
shearing machine disclosed in this Publication includes a cylinder case 
detachably mounted on one end of an arm of a power shovel by means of a 
rotatable device, and a pair of cutters. Each cutter includes a shearing 
blade pivotably mounted on a support shaft extending transversely in the 
cylinder case. 
The shearing machine disclosed in the above United States Patent is 
constructed so that the upper movable jaw 3 may be inserted into the 
recess 8 formed in the lower stationary jaw 2. Further, each of the upper 
and lower jaws includes attached thereto a pressure plate 10, 9. This 
causes such a shearing machine to be relatively large in size, complicated 
in construction, and significantly heavy in weight, thus making 
manufacturing cost thereof relatively high. In addition, such a shearing 
machine requires a relatively large-sized power shovel. 
On the other hand, the shearing machine disclosed in the above Japanese 
Publication is relatively small in size and lightweight. It should be 
noted, however, that, in such a shearing machine, the cutter body tends to 
move sideways away from a steel material upon shearing thereof in a 
direction perpendicular to open close direction of the cutter. Thus, such 
a shearing machine becomes incapable of securely shearing or cutting a 
steel material over time of use. 
SUMMARY OF THE INVENTION 
Accordingly, it is a main object to provide a steel material shearing 
machine which is constructed, upon shearing of a steel material, to 
prevent an upper movable jaw from moving sideways away from a lower 
stationary jaw, so as to securely shear such a steel material. 
In order to achieve the above object, the invention provides a steel 
material shearing machine which comprises a lower stationary jaw 
detachably mounted on one end of an arm of a working machine for rotatable 
and tiltable movement, the lower stationary jaw having attached thereto a 
plurality of shearing blades, an upper movable jaw having a plurality of 
shearing blades adapted to be opened and closed in a scissors-like manner 
relative to the shearing blades of the lower stationary jaw so as to shear 
an article to be sheared, and a hydraulic cylinder for pivotally moving 
the upper movable jaw. The forward-end shearing blade of the lower 
stationary jaw and the forward-end shearing blade of the upper movable jaw 
are symmetrically arranged to the rest of the shearing blades of the jaws 
with respect to a shearing plane defined by opposite side surfaces of said 
lower stationary jaw and upper movable jaw. 
The lower stationary jaw and upper movable jaw may respectively include an 
optional number of shearing blades, for example, two or three shearing 
blades. 
When it is intended to shear a steel material, the upper movable jaw is 
pivoted toward its closed position. By this, first the forward-end 
shearing blade of the upper movable jaw becomes inter-engaged with the 
forward-end shearing blade of the lower stationary jaw. Then, the shearing 
blades of the upper and lower jaws cooperate to shear or cut a steel 
material clamped therebetween. It will be appreciated that a horizontal 
component of the shearing force acting on the upper movable jaw is borne 
or supported by the inter-engaged, forward-end shearing blades of the 
upper and lower jaws, which prevents the upper movable jaw from moving 
sideward in a direction perpendicular to the open-close direction of the 
upper jaw.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Several embodiments of a steel material shearing machine according to the 
invention will be explained in detail below with reference to FIGS. 1 
through 7. 
FIRST EMBODIMENT 
A steel material shearing machine (referred to simply as "shearing machine" 
hereinafter) 21 according to a first embodiment of the invention is 
detachably mounted on a forward end of an arm 23 of a working machine 
which could be various types of machines, such as a power shovel 22, for 
rotational and tiltable movement, as shown in FIG. 2. The shearing machine 
21 includes, as shown in FIGS. 1 and 2, a lower stationary jaw 25 having 
two lower shearing blades 24a and 24b, an upper movable jaw 27 having 
three upper shearing blades 26a, 26b and 26c adapted to be closed in a 
scissors-like manner relative to the lower shearing blades 24a and 24b of 
the lower stationary jaw 25 so as to cut a steel material, and a hydraulic 
cylinder 28 for moving the upper movable jaw 27 in a swingable manner. 
The lower stationary jaw 25 is forwardly protruded integrally from a 
rotational end place 30 and a support frame 31 fixedly connected to the 
rotational end plate. The upper movable jaw 27 is pivotally connected to 
the lower stationary jaw 25 at its upper, rearward portion via a pivot 
shaft 32, so that the upper movable jaw 27 may be closed in a 
scissors-like manner. Engagement portions 33 and 34 oppositely disposed on 
the lower stationary jaw 25 and upper movable jaw 27, respectively, 
cooperate to form a concave configuration. The lower shearing blades 24a 
and 24b and the upper shearing blades 26a, 26b and 26c are attached to the 
respective concave engagement portions 33 and 34 by means of a plurality 
of bolts 35 so that they may be engaged with each other whereby preventing 
a steel material clamped therebetween from slipping forwardly. Prevention 
of a steel material from slipping forwardly may be achieved by forming an 
obtuse abutment angle between the forward shearing blade 24a and the next 
shearing blade 24b of the lower jaw 25, and between the forward shearing 
blade 26 a and the next shearing blade 26b of the upper jaw 27. 
The shearing blades 24a and 24b of the lower jaw 25 are arranged so that 
the forward shearing blade 24a of a shorter length is offset relative to 
the shearing blade 24b of a longer length along the longitudinal 
direction, as shown in FIG. 3. The shearing blades 26a, 26b and 26c of the 
upper jaw 27 each having a relatively short length are arranged so that 
the forward-end shearing blade 26a a is offset relative to the succeeding 
shearing blades 26b and 26c along the longitudinal direction, as also 
shown in FIG. 3. Specifically, the shearing blades of the upper and lower 
jaws are so arranged that, when the jaws are closed, a side surface 24a' 
of the forward shearing blade 24a of the lower jaw 25 and a side surface 
26a' of the forward-end shearing blade 26a of the upper jaw 27 are 
slidably inter-engaged, while a side surface 24b' of the rearward shearing 
blade 24b of the lower jaw 25 and side surfaces 26b' and 26c' of the 
succeeding shearing blades 26b and 26c of the upper jaw 27 are slidably 
inter-engaged. Thus, when the shearing blades 24a and 24b of the lower jaw 
25 and the shearing blades 26a , 26b and 26c of the upper jaw 27 are 
inter-engaged, the shearing blades 26a and 24a are firstly engaged with 
each other at the respective side surfaces 26a' and 24a', so as to prevent 
the upper movable jaw 27 from moving away from the lower stationary jaw 25 
in a direction perpendicular to the open-close direction of the upper jaw 
27, by countering on the opposite side surfaces 26a', 24a''' a component 
(shown by arrow marks in FIG. 5) of the shearing force generated when the 
lower shearing blade 24b and upper shearing blades 26b, 26c are 
inter-engaged. 
A cylinder case 41 is integrally attached to the rotatable end plate 30 and 
the support frame 31, the cylinder case being extended upwardly. A pair of 
hydraulic cylinders 28 are disposed within the cylinder case 41 in 
parallel relationship with each other (only one of the cylinders is shown 
in the drawings). One end or proximal end of each of the hydraulic 
cylinders 28 is pivotally connected to the upper portion of the cylinder 
case 41 via an attachment shaft 42. A distal end of a rod 45 of each of 
the hydraulic cylinders 28 is connected to an attachment piece 46 formed 
in the upper portion of the upper movable jaw 27 via an attachment pin 47. 
Thus, reciprocal movement of the rod 45 causes the upper movable jaw 27 to 
be opened and closed in a scissors-like manner so as to shear or cut a 
steel material. 
A fixation end plate 51 is connected to the rotatable end plate 30. An 
attachment bracket 52 is fixedly connected to the fixation plate 51. The 
attachment bracket 52 is provided with two attachment arms 53, 53 
protruding from the rearward surface of the attachment bracket 52. The two 
attachment arms 53, 53 are are pivotally mounted to an arm 23 of a working 
machine 22. 
A bearing 54 having an internal gear is attached to the rotational end 
plate 30. The fixation end plate 51 houses therein a hydraulic motor 
having a pinion, or a rotational braking unit having a pinion for freely 
rotational movement and a swivel joint (none of them are shown in the 
drawings). Thus, when the internal gear is rotated by means of the pinion 
directly connected to the hydraulic motor, the rotatable end plate 30 is 
rotated so as to cause the entire shearing machine 21 to be rotated in the 
range of 360 degrees relative to the arm 23 of the working machine 22. 
Operation of the shearing machine according to the invention will be 
explained below. 
With the upper movable jaw 27 maintained in its open position, the working 
machine 22 is operated so that a steel material may be clamped between the 
lower stationary jaw 25 and the upper movable jaw 27. Then, the hydraulic 
cylinder 28 is actuated to be extended so as to close the upper movable 
jaw 27. It should be recalled that the shearing blade 24a of the lower jaw 
25 and the shearing blade 26a of the upper jaw 27 are maintained at an 
obtuse angle relative to the adjacent shearing blade 24b of the lower jaw 
25 and the adjacent shearing blade 26b of the upper jaw 27, respectively. 
Accordingly, when the upper movable jaw 27 is actuated to be closed, a 
steel material, once clamped between the jaws, will be urged by the 
forward-end shearing blade 24a of the lower jaw 25 and the forward-end 
shearing blade 26a of the upper jaw 27 inwardly or rearwardly of the lower 
stationary jaw 25 and upper movable jaw 27. Thus, such a steel material is 
clamped without slipping forwardly and sheared or cut by the cooperative 
action of the shearing blades 24a and 24b of the lower jaw 25 and the 
shearing blades 26 a, 26b and 26c of the upper jaw 27. 
It should be also recalled that the forward-end shearing blade 26a of the 
upper jaw 27 and the forward-end shearing blade 24a of the lower jaw 25 
are respectively disposed in staggered fashion with respect to the 
shearing blades 26b and 26c of the upper jaw 27 and the shearing blade 24b 
of the lower jaw 25. In other words, the blade 26a and the blade 24a are 
symmetrically arranged relative to the rest of the shearing blade of the 
jaws with respect to a shearing plane defined by opposite side surfaces of 
the lower jaw 25 and the upper jaw 27. Thus, first the forward end 
shearing blade 26a of the upper movable jaw 27 is engaged with the 
forward-end shearing blade 24a of the lower stationary jaw 25, as shown in 
FIG. 4, then the rearward shearing blade 24b of the lower stationary jaw 
25 and the rearward shearing blades 26b and 26c of the upper movable jaw 
27 are inter-engaged with each other, as shown in FIG. 5. As a result, 
transverse force, to the upper movable jaw 27, which is derived from the 
shearing force applied to the upper movable jaw 27 upon shearing a steel 
material will be borne by the opposite side surfaces 24a' and 26a' of the 
inter-engaged shearing blades 24a and 26a, which prevents the upper 
movable jaw 27 from moving away from the lower stationary jaw 25 in a 
direction perpendicular to the open-close direction of the jaws. 
Accordingly, the shearing blades 24a and 24b of the lower jaw 25 and the 
shearing blades 26a, 26b and 26c of the upper jaw 27 may cooperate to 
securely shear or cut a steel material clamped therebetween. After a steel 
material has been sheared, the hydraulic cylinder 28 is contracted, 
whereby the upper movable jaw 27 is actuated to be opened to its original 
or home position. 
SECOND EMBODIMENT 
FIG. 6 is a diagrammatic perspective view illustrating an alternative 
arrangement of shearing blades attached to the lower stationary jaw and 
upper movable jaw. In this embodiment, the upper movable jaw 27 includes 
mounted thereon a relatively short shearing blade 61a and a relatively 
long shearing blade 61b. These blades 61a and 61b respectively correspond 
to the shearing blades 24a and 24b of the lower stationary jaw 25. The 
forward shearing blade 61a of the upper jaw 27 is disposed in staggered or 
angled manner relative to the rearward shearing blade 61b. The shearing 
blade 61a is also arranged so as to be engaged with the forward shearing 
blade 24a of the lower stationary jaw 25. 
THIRD EMBODIMENT 
FIG. 7 diagrammatically illustrates a further alternative arrangement of 
shearing blades attached to the lower stationary jaw and upper movable 
jaw. In the illustrated embodiment, the lower stationary jaw 25 includes 
attached thereto three shearing blades 71a, 71b and 71c of a relatively 
short length. These shearing blades 71a, 71b and 71c respectively 
correspond to the shearing blades 26a, 26b and 26c of the upper movable 
jaw 27, such as shown in FIG. 1. The forward-end shearing blade 71a of the 
lower jaw 25 is arranged in staggered or angled manner relative to the 
remaining shearing blades 71b and 71c of the lower jaw 25, so that the 
shearing blade 71a is inter-engaged with the forward-end shearing blade 
26a of the upper jaw 27. As a modification of this embodiment, the 
shearing blades 26b and 26c of the upper jaw 27 and shearing blades 71b 
and 71c may also be arranged in a staggered or angled manner, so that a 
horizontal component of the shearing force generated upon shearing a steel 
material will be born by the shearing blades 26a, 26c and 71a, 71c of the 
upper and lower jaws 27 and 25, respectively. 
In accordance with the invention, the shearing blades of the lower 
stationary jaw and the shearing blades of the upper movable jaw, which are 
to be inter-engaged therewith, are arranged so that the forward shearing 
blade of the lower jaw and forward shearing blade of the upper jaw are 
symmetrically arranged relative to the rest of the shearing blade of the 
jaws with respect to a shearing plane defined by opposite side surfaces of 
the lower jaw and the upper jaw. Accordingly, upon shearing of a steel 
material, first the forward shearing blade of the upper jaw and forward 
shearing blade of the lower jaw are inter-engaged with each other. The 
inter-engagement of the forward shearing blades prevents the upper movable 
jaw is prevented from moving sideward from the lower stationary jaw, while 
a steel material is sheared by means of the remaining shearing blades. 
This contributes to secure shearing of a steel material. It is to be noted 
that the forward shearing blades of the upper and lower jaws are disposed 
in a simple staggered or angled manner relative to their respective 
adjacent shearing blades. This permits a shearing machine to be made 
simple and light-weight construction. Thus, the invention provides a 
shearing machine which may be produced easily and inexpensively and which 
may be rotatably mounted on an end of an arm of a working machine. 
The principles, preferred embodiments and modes of operation of the present 
invention have been described in the foregoing specification. It should be 
noted, however, that the invention is not limited by such illustrative 
embodiments. Variations and changes may be made by one having ordinary 
skill in the art without departing from the spirit of the present 
invention. Accordingly, the foregoing detailed description should be 
regarded as exemplary in nature and not limiting the scope and spirit of 
the invention set forth in the appended Claims.