Metal working – Means to assemble or disassemble – Spring applier or remover
Reexamination Certificate
2002-09-05
2003-11-04
Vidovich, Gregory (Department: 3726)
Metal working
Means to assemble or disassemble
Spring applier or remover
C029S235000, C029S243560, C029S451000, C029S522100
Reexamination Certificate
active
06640405
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a ring installation method and a ring installation jig used for assembling an anti-slip-off ring into a joint part at which a link and a link coupling pin are coupled to each other, when assembling a link chain that constitutes a crawler belt particularly for use in a crawler-mounted construction machine.
BACKGROUND ART
As shown in
FIG. 9
, a known crawler belt
1
for use in construction machines such as hydraulic excavator and bulldozers is comprised of a plurality of track shoes
2
that serve to contact the ground. The track shoes
2
are respectively attached, by means of attachment bolts, to links
4
that constitute an endless link chain
3
. This link chain
3
is assembled by successively forcing link-coupling pins
6
(hereinafter simply referred to as “pin”) into tubular bushings
5
such that both ends of each pin project outwards from the respective ends of the right and left links
4
. In the link chain
3
, the adjacent links
4
are articulately connected to each other by the pins
6
at their ends in such a condition that these ends are spaced apart from each other. At the end of each link
4
, there are disposed (i) a lubricant sealing member which hermetically seals a lubricant for preventing an internal wear occurring between each pin
6
and each bushing
5
and (ii) a spacer for preventing crushing of the lubricant sealing member so that the lubricant stored within the pin
6
can be supplied to the space between the pin
6
and the bushing
5
.
The link chain
3
of such a crawler belt
1
exerts a great force on the pins
6
in a thrusting direction, when the crawler belt
1
is in service. Therefore, each pin
6
is provided with an anti-slip-off means at both ends thereof. A typical anti-slip-off means for the pin
6
is designed such that a groove is inscribed in its circumferential direction in both ends of the pin
6
and an anti-slip-off ring is fitted in each groove so as to prevent the pin
6
from falling out. Herein, an expandable/contractible ring made of an elastic metal material such as snap rings is used as the anti-slip-off ring.
Japanese Patent Application No. 11-182264 (1999) associated with a previous invention filed by the inventors of the present invention discloses a means for preventing slip-off of pins in the link chain of a crawler belt, as a fixing arrangement for crawler belt links and pins. In the previous invention, as shown in
FIGS. 10A
,
10
B, a link chain
3
has annular space sections
9
each of which is formed between the periphery of the open end of a pin insertion hole
7
in each of right and left links
4
and an end of a pin
6
. An anti-slip-off ring A is fitted in each annular space section
9
so that the pin
6
is prevented from moving in its axial direction and falling out. For this arrangement, the periphery of the open end of each pin insertion hole
7
has a tapered inner face
7
a
which gradually expands outwardly from the pin insertion hole
7
. The pin
6
has, at both ends thereof, a tapered outer face
6
b
which faces the tapered inner face
7
a
. The inclination angle of the tapered outer face
6
b
with respect to the axial center line of the pin
6
is slightly smaller than the inclination angle of the tapered inner face
7
a
. Each annular space portion
9
defined by the tapered outer face
6
b
and the tapered inner face
7
a
expands outward in a flared fashion. The anti-slip-off ring A is circular in section and assumes the form of a partly cut-away annular ring. In addition, the anti-slip-off ring A is made of an elastic metal material so that it can be expanded and contracted, increasing and decreasing in diameter.
As described earlier, in the conventional crawler belt
1
, the anti-slip-off ring A, which is used as a means for preventing the slip-off of the pin
6
for coupling the link chain
3
, is formed from an elastic metal material. When mounting the anti-slip-off ring A in a groove formed at an end of the pin or a recess defined by the inclined surfaces, such an operation becomes necessary that the ring A is enlarged (i.e., expanded in diameter) so as to be wider than the diameter of the pin
6
and then pushed inward. In cases where the aforesaid snap ring is fitted in the groove formed at the end of the pin as the anti-slip-off ring, the snap ring is first expanded by widening a ring enlargement hole formed at the ring's ends, using known pliers which is a specialized tool for mounting a snap ring, and then fitted in the pin engagement groove. In this case, the workman has to manually attach the snap ring one by one. Since the width of the groove into which the ring is to be fitted should be provided with a margin in order to facilitate the fitting of the ring into the groove, the pin moves the distance corresponding to the margin after the installation of the ring. In addition, there is such a risk that if great external force is exerted in a thrusting direction, the anti-slip-off ring or the groove might be broken, resulting in falling out of the pin.
Since the anti-slip-off ring A used in the anti-slip-off means is in the form of a partly cut-out annular ring having a circular section and is made of an elastic metal material, when expanded by a specialized tool similar to the aforesaid pliers, the ring A cannot be uniformly enlarged but is just widened at its cut-out portion because of its inherent structure. Therefore, an extremely large power is necessary for the expansion of the ring so that the ring fitting work needs to be carried out by substantially two workers and it takes a long time (about 3 minutes) to fit one ring. As a result, sequential operations for coupling a number of links involves prolonged assembling which inevitably entails increased cost. Another problem is that it is currently difficult to automate the process of mounting the anti-slip-off rings.
The present invention is directed to overcoming the above problems and a prime object of the invention is therefore to provide a ring installation method capable of efficiently carrying out an operation when expanding an anti-slip-off ring and mounting it on an end of a link coupling pin, the operation being such that the anti-slip-off ring can be uniformly widened to be fitted on the end of the pin, then pushed until it reaches an engagement position and mounted thereat. Another object of the invention is to provide a ring installation jig used for carrying out the above ring installation method.
DISCLOSURE OF THE INVENTION
In accomplishing the above prime object, there has been provided, in accordance with the invention, a ring installation method for mounting an anti-slip-off ring used for securely attaching a link coupling pin to links in a crawler belt of a vehicle, wherein the anti-slip-off ring is mounted on an annular open space defined between an open end of a pin insertion hole in a link and an insertion end of the pin exposed within the open end, by pressing the anti-slip-off ring against the outer periphery of an end of the pin while the anti-slip-off ring is expanded and by pushing the anti-slip-off ring in its expanded state with a pusher to slide it from the end of the pin to a predetermined position.
According to the invention, when successively coupling links with coupling pins during a link-chain assembling operation, an anti-slip-off ring is mounted on an insertion end of a pin, the insertion end being exposed within the open end of a pin insertion hole in a link. For installing the anti-slip-off ring, the anti-slip-off ring is firstly expanded from its bore side by use of a ring installation jig so as to be brought into a condition in which the ring can be fitted on the outer periphery of the pin. The ring is then pressed against the outer periphery of the pin's end. With this procedure, the anti-slip-off ring is substantially uniformly expanded so that it can be easily fitted on the pin. Thereafter, the anti-slip-off ring is slid to a predetermined position on the pin by pushing it with a pusher while the ring being kept in its
Armstrong Westerman & Hattori, LLP.
Komatsu Ltd.
Omgba Essama
Vidovich Gregory
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