Apparatus for build-up welding with cooling of a sealed and lubricated track link

A method and apparatus for feeding coolant to the interior of a connecting pin during build-up welding of a track link assembly, for protecting the peripheral seal members of the connecting pin from the welding heat, comprising a coolant charging and discharging adapter having a forcibly butting conical shaped end to be placed in contact with an opening in the lateral end face of the connecting pin and an elongate pipe for feeding a coolant through said adapter into said connecting pin interior. The coolant is removed continuously or intermittently during welding through an annular passageway formed in the adapter concentrically about the pipe, or through a passageway similarly formed by an insertion portion carried by said adapter. The adapter is supported by a suitable support member, being aided by a compression spring disposed therebetween, and connected to a retractable mounting plate urged by fluid pressure operated cylinder and piston means for maintaining the adapter forcibly butted against the end face of the connecting pin.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a process for the build-up welding, or 
submerged arc welding, of the worn surface of the sealed and lubricated 
track link with its joint portion having the lubricating oil seal, and 
also to a cooling device for the protection of the seal members. 
2. Description of the Prior Art 
As the conventional track link is constructed simply by combining each pair 
of adjacent links with a single connecting pin, these links can be welded 
in a build-up process on a work bed of a build-up welding machine, after a 
series of connected links have been removed from a drive unit of a 
bulldozer. 
However, the build-up welding of a sealed and lubricated track link 
assembly, which has recently come into general use, presents an 
inconvenience since the connecting bushings and pins must be first removed 
to disassemble the track link assembly into a unit link, in order to 
insure that the seal members will not be degraded or damaged by the 
welding heat. 
SUMMARY OF THE INVENTION 
A primary object of the present invention, therefore, is to provide a 
method of continuous build-up welding of a sealed and lubricated track 
link assembly, similar to the welding methods employed with the 
conventional link assembly. 
Thus, the apparatus of the present invention is designed to take advantage 
of the fact that the connecting pins of a sealed and lubricated track link 
assembly have oil holes at each end, and to circulate continuously a 
coolant, such as cooling water, all through the inside of the oil holes 
during the build-up welding, thus preventing the burning-out of the seal 
members. 
Accordingly, the foregoing object and others as well are achieved by a 
process for build-up welding of a sealed and lubricated track link 
assembly which features inserting, or forcibly butting, an adapter having 
two fluid passages for charging and discharging coolant against an oil 
hole formed in the lateral end surface of a link connecting pin to create 
a water-tight fit therewith, and feeding and draining a coolant 
continuously or intermittently into the oil hole, with the track link to 
be welded being cooled from its inside, while simultaneously performing a 
build-up welding operation thereon. 
An apparatus for feeding coolant to the interior of a connecting pin during 
build-up welding of the track link assembly according to the method just 
described, so as to protect the peripheral seal members of the connecting 
pin from the welding heat, comprises a coolant charging and discharging 
adapter having a forcibly butting conical-shaped end to be placed in 
forced contact with an opening in the lateral end face of the connecting 
pin for the sealed and lubricated track link assembly and an insertion 
portion connected to the forcibly butting conical face for being inserted 
into an oil hole in the link connecting pin. Arranged within both the 
conical butting face and the insertion portion of the adapter are at least 
two fluid passages designed for charging and discharging the coolant. The 
adapter is supported by a suitable support member, being aided by a 
compression spring disposed therebetween, and connected to a convenient 
retractable means for generating compression power on the compression 
spring for maintaining the the adapter forcibly butted against the end 
face of the connecting pin. 
The foregoing mode of structure further permits eliminating the disassembly 
of the link assembly to save working hours and also permits cleaning the 
inside of the oil holes to remove solid mass therein which is undesirable 
to lubrication.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
Referring now to the drawings, and more particularly to FIG. 1 thereof, in 
the usual structure of a sealed and lubricated track link assembly, the 
link elements 1, 2, 3 and 4 are connected together by a bushing 5 and a 
connecting pin 6. Seal members 7 are disposed in the external end planes 
of the bushing 5 and are fitted concentrically about the pin 6. The seal 
members 7 consist of radially inwardly disposed thrust rings 8 and 
radially outwardly disposed oil-resistant rings 9, of polyethylene or 
other suitable material. An oil hole 10 formed axially in the connecting 
pin 6 has an opening 11 at one end, a rubber stopper 12 and a plug 13 
disposed in the opening 11, and a fine oil feed orifice 14 formed radially 
in the side wall of the pin 6. 
The apparatus of the present invention will now be described. A coolant 
feeding adapter 20 of substantially cylindrical configuration has a 
conical end portion 21 providing a face which may be forcibly abutted with 
the opening 11 of a connecting pin 6. A tubular insertion portion 22 of 
the adapter 20 may be readily inserted into the oil hole 10 and the 
coolant may be introduced through an elongate pipe 23 which protrudes 
along the center axis of the adapter 20 and is, at least along a part of 
its length, concentric with the tubular insertion portion 22. An annular 
returning passage 24 is formed inside the adapter between the coolant 
introducing pipe 23 and the tubular insertion portion 22. A radial drain 
hole 25 formed in the adapter 20 is connected to the returning passage 24 
adjacent one end thereof, being closed by a plug 26, through which a 
flexible hose 27 is connected to the drain hole and returning passage. A 
coolant feeding hose 28, on the other hand, is connected through a plug 29 
to a water feed hole 30 formed in the adapter and connected to the pipe 
23. The rear end of the pipe 23 is closed by a blind cover 31 fitted 
thereto. The hoses 27 and 28 are connected to common pipes 270 and 280, 
respectively, as shown in FIG. 4. 
As further shown in FIG. 4, a compression spring 32 is utilized to apply 
thrust to the adapter. Support members 33, being provided one each for 
each adapter, are mounted to a mounting plate 34 so as to be variable in 
pitch, according to the respective link pitch. The mounting plate 34 is 
connected to a retractable mechanism for generating compression power, 
such as a cylinder 35, which may be actuated pneumatically or 
hydraulically, through a rod 36 and a bracket 37 secured on the mounting 
plate. A bracket 38 for the other end of the cylinder 35 is incorporated 
in a fixed member 39, such as a welding bed, and a stopper 40 is mounted 
opposite the mounting plate 34, but lower than the link. 
As regards the operation of the apparatus, the track link, first being 
dismounted by removing the rubber stopper 12 and the plug 13 and by 
draining lubricant from its pin 6, is placed on the welding bed, as shown 
in FIG. 4. The cylinder 35 is then actuated to advance the mounting plate 
34 and, after the coolant introducing pipe 23 is inserted into the oil 
hole 10 of the pin 6, while the tapered face of forcibly-butting face 21 
of the adapter is brought into close contact with the opening 
circumference of the oil hole, the coolant feeding pump, not shown, is 
actuated to forcibly feed coolant. Thereafter, the welding arc is ignited 
to initiate the build-up welding process. 
In this case, the insertion portion 22 of the adapter 20 need not be in 
close contact with the internal face of the oil hole, because the butting 
face 21 of the adapter is pressed tightly and almost uniformly to the 
circumference of the opening by the effect of the compression coil spring 
32 so as to maintain the water tightness thereof. The forcibly-fed coolant 
passes from the hose 28, through the pipe 23, and is discharged from the 
end of the pipe 23, and, after filling outside the pipe or the whole zone 
of the oil hole and taking the welding heat transmitted to the pin and the 
bushing, passes through the annular returning path 24 to flow out through 
the drain hose 27. The direction of coolant circulation is illustrated by 
the arrows in FIG. 2. 
The coolant preferably should be forcibly fed, not only during the welding 
operation, but also after the completing of the welding operation for 
removing the heat remaining therefrom. 
According to this invention, as the seal members fitted to the periphery of 
the pins are maintained at a temperature below their heat-resisting 
temperature, the seal members are prevented from thermal degeneration, so 
that the track links may be subjected to the build-up welding without 
removal of the pins. 
Obviously, many modifications and variations of the present invention are 
possible in light of the foregoing teachings. 
For example, in the embodiment illustrated in FIG. 3, wherein a 
modification of the adapter 20 is illustrated, the insertion portion 22 is 
essentially eliminated and the conical end face 21 of the adapter 20 is so 
tapered as to be slightly insertable into the oil hole 10 of the 
connecting pin 6. In this case, the returning passage 24 is constituted by 
the annular space defined between the internal periphery of a bore 
provided in the adapter 20 and the coolant introducing pipe 23. Obviously, 
the drain hole 25 continues to be connected to the passage 24, as in the 
embodiment of FIG. 2, and the rear of the bore forming the passage 24 must 
be closed in a suitable manner. As with the embodiment of FIG. 2, in this 
case also, the butting face 21 of the adapter is pressed tightly and 
uniformly against the circumference of the opening of the oil hole by the 
effect of the compression coil spring 32 so as to maintain the water 
tightness thereof. 
Thus, according to the present invention, the design and arrangement of the 
coolant feeding piping and the circulation passage for the adapter are 
discretional, and also the mounting position of each hose is not critical. 
Furthermore, the feeding direction of the coolant may be reversed, and the 
feed system may be a suction system, rather than the forcible feeding 
system described herein. 
Accordingly, it is to be understood that within the scope of the appended 
claims, the present invention may be practiced otherwise than as 
specifically described herein.