Severing by tearing or breaking – Methods
Reexamination Certificate
2001-03-05
2003-06-03
Shoap, Allan N. (Department: 3724)
Severing by tearing or breaking
Methods
C225S097000, C225S103000
Reexamination Certificate
active
06571999
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a machine for fracture separating a connecting rod and a method for fracture separating a connecting rod using the machine. More particularly, it relates to a machine and a method for fracture separating a connecting rod, in which a half-split type mandrel is fitted into an opening of a large end portion of a connecting rod to expand the opposed half portions of the mandrel and thus separate said opening portion, and the large end portion of said connecting rod is thereby fracture separated into a cap portion and a rod portion along embrittled portions, which are provided in advance on the inner surface of the opening portion.
2. Related Arts
A connecting rod (hereinafter referred to as a con-rod) is to connect between the crankshaft and the piston head of an engine. The con-rod has a bearing portion or an opening of the large end portion (hereinafter referred to as a large end bearing) and another bearing portion or a small end portion (hereinafter referred to as a small end bearing). The large end bearing supports a journal of said crankshaft, while the small end bearing supports the piston pin. The piston pin is allowed to penetrate the small end bearing and both ends thereof are supported by the bearings of the piston head. On the other hand, the large end bearing is separated into halves, or rod and cap portions, at a predetermined diametric position to encircle a journal of the crankshaft. After that, the rod and cap portions are bolted securely to each other to support said journal.
There is an FS (Fracture Separation) technique available for separating the large end portion of the con-rod into halves or rod and cap portions.
FIG. 1
is an explanatory view illustrating the fracture of the con-rod by a related FS technique. As shown in
FIG. 1
, along the axial direction, provided are in advance embrittled portions, for example, notch grooves
2
a,
2
a
subject to a concentrated stress at predetermined diametrical positions of the large end bearing
2
of the integral preform con-rod
1
. Then, the large end bearing
2
is mated with the half portions
4
a,
4
b
of a half-split type mandrel
4
which are separated into halves at the positions corresponding to the notch grooves
2
a
. Thereafter, a wedge
5
is inserted in between the mandrel half portions
4
a,
4
b
to provide a separating force therebetween, thereby fracture separating a large end portion
1
a
starting from the notch grooves
2
a,
2
a
. The present fracture separation method is to thus fracture separate the con-rod
1
into a rod portion
1
A and a cap portion
1
B.
Now, a con-rod fracture machine is considered which causes fracture separation of the large end portion
1
a
of the con-rod into the rod portion
1
A and the cap portion
1
B in accordance with the aforementioned FS technique. In the machine, any one of the mandrel half portions
4
a,
4
b,
for example, the mandrel half portion
4
a
is fixed to a support member
7
, whereas the other mandrel half portion
4
b
is fixed to a support member
8
which is slidable apart from the mandrel half portion
4
a
. On the support member
8
, there is provided a clamp member
9
for clamping the small end portion
1
b
of the con-rod
1
. Also provided thereon are clamp members
10
,
10
and
11
,
11
for clamping both right and left shoulder portions of and both sides of the rod portion
1
A of the large end portion
1
a.
Moreover, provided on the support member
7
are clamp members
12
,
12
for clamping both right and left shoulder portions of the cap portion
1
B.
Upon fracture of the large end portion
1
a,
each of the clamp members
9
-
12
first clamps securely the con-rod
1
at the front, back, right, and left thereof. Subsequently, the wedge
5
is used to expand the mandrel half portions
4
a,
4
b
and thus fracture separate the large end portion
1
a,
or the large end bearing
2
along the notch grooves
2
a,
2
a
. As the large end portion
1
a
is fracture separated, the support member
8
moves in the direction shown by the arrow to cause the con-rod
1
to be separated into halves, or the rod portion
1
A and the cap portion
1
B.
However, the aforementioned con-rod fracture machine clamps both the right and left shoulder portions of the rod portion
1
A of the con-rod
1
or the vicinity thereof, both the right and left side portions, the large end portion
1
a,
and the small end portion
1
b.
This clamping arrangement readily causes the aforementioned con-rod fracture machine to provide chipping upon fracture and a bad surface property (surface roughness) for the fracture planes. In addition, movement of only one half of the mandrel or the mandrel half portion
4
b
(one-half movable mandrel) will not allow the large end bearing
2
to be uniformly loaded for expansion. Therefore, such a problem is introduced that the con-rod fractured by the aforementioned con-rod fracture machine is provided with a large amount of strain and an unstable shape of split planes.
SUMMARY OF THE INVENTION
The present invention was developed in view of the aforementioned problems. An object of the present invention is to provide a con-rod fracture machine which eliminates chipping upon fracture and provides stable properties for fracture surfaces. Another object is to provide a method for fracturing a con-rod using the machine.
To achieve the aforementioned object, the con-rod fracture machine according to the present invention comprises first and second support members for horizontally supporting a large end portion and a rod portion of a con-rod. The first and second support members are arranged movably apart from each other on a base of a pallet for placing thereon the con-rod to be fractured. The machine also comprises a half-split type mandrel, vertically provided on said first and second support members, comprising two mandrel half portions with each outer peripheral surface thereof fitted into and in contact with an inner surface of an opening of said large end portion. Moreover, the machine comprises a wedge, with tapered surfaces in contact with opposite edge surfaces of said mandrel half portions, for separating said mandrel half portions uniformly apart from each other. The machine also comprises an actuator for applying a load to said wedge. Furthermore, the machine comprises control means for applying an initial load to said actuator to bring each of said mandrel half portions into contact with said inner surface of the opening and thereafter applying a fracture load to instantaneously fracture said opening.
On the other hand, the method for fracture separating a con-rod according to the present invention comprises a step of placing a con-rod to be fractured on a pallet. The method further comprises a step of holding said con-rod by supporting a large end portion and a rod portion of said con-rod by means of first and second support members arranged on a base of said pallet movably apart from each other. Furthermore, the method comprises a step of bringing each outer peripheral surface of a half-split type mandrel mateably into contact with the inner surface of an opening of said large end portion. Here, the half-split type mandrel is vertically provided on said first and second support members and comprises two mandrel half portions. The method also comprises a step of applying an initial load to the inner surface of said opening using a wedge to bring each of said mandrel half portions into contact with the inner surface of said opening. The wedge has tapered surfaces in contact with opposite edge surfaces of said mandrel half portions. Finally, the method comprises a step of fracturing said opening instantaneously by applying a fracture load to the inner surface of said opening using said wedge.
As described above, the half-split type mandrel is mated with the opening of the large end portion of the con-rod. Then, the opposite mandrel half portions are expanded to expand said opening in order to fracture separate said con-rod into cap an
Frishauf Holtz Goodman & Chick P.C.
Prone Jason
Shoap Allan N.
Yasunaga Corporation
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