Coating apparatus – With means to centrifuge work – Coating inside of hollow work
Reexamination Certificate
1998-09-25
2001-02-06
Edwards, Laura (Department: 1734)
Coating apparatus
With means to centrifuge work
Coating inside of hollow work
C425S433000
Reexamination Certificate
active
06183557
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a suspension system for a pipe lining machine and more particularly, to a damping assembly for damping vibrations in the belts used to support and rotate pipes during the lining operation.
BACKGROUND OF THE INVENTION
Concrete-lined pipes of exceptionally large diameter are generally used as buried conduits for conducting drinking water, irrigation water, and other fluids. To construct such a pipe, concrete mortar is placed inside a steel pipe which is then spun to centrifugally distribute the concrete mortar in an even thin layer on the inside wall of the pipe.
A machine, generally known as lining machine, is used to perform the operation and basically consists of multiple belt assemblies, usually three to five, which are spaced apart for supporting the pipe along its length. A side view of a pre-existing lining machine
10
is illustrated in FIG.
1
. The side view shows the typical belt arrangement for each belt assembly of the lining machine. Each belt
12
is formed into a loop which wraps around a set of four pulleys, as depicted in FIG.
1
.
The pipe is supported by the belts at the portion between the two upper pulleys
14
,
16
. The left upper pulley
14
is generally fixed in position and powered by a drive motor to provide the necessary drive force to spin the pipe at sufficient rotational speeds to adequately pack the mortar on the inside wall of the pipe. The right upper pulley
16
can be adjusted toward or away from the left pulley before the spinning operation to adapt the machine to a range of pipe sizes. The right lower pulley
20
may also be adjusted. The left lower pulley
18
is fixed in position. All pulleys are fixed in position during operation.
To mortar line a pipe, the pipe is initially rotated at a steady but relatively low speed and a mortar feeding lance is moved inside the pipe to pour the mortar material along the length of the pipe. The pipe is then accelerated to a desired rotational speed to pack the mortar against the internal pipe wall for a sufficient period of time to allow the mortar to dewater.
Due to the elastic property of the belts, the generally uneven roundness of the pipe, and the imbalance in the pipe caused by an uneven mortar thickness caused by the rotation of the pipe around its mass (i.e., gravity) center, the pipe vibrates on the belts while it is rotating. The pipe and the belts together constitute an oscillating system with a particular frequency of its own, its so-called “natural frequency.” When the pipe is rotated at high speeds, the reciprocating movements of the belts come into the natural frequency range of this system. When this happens, the pipe and belts tend to move independently of the motion imparted to them by the drive motor.
The vibration of the system is especially large when in the natural frequency of the system before reaching the packing speed. If the pipe is excessively out of balance, the vibration can be very severe and the pipe can bounce off of the belts, causing the belts to slack and sometimes slip away from the pulleys. This damages the belts and may also cause the pipe to fall off of the machine, thereby creating a dangerous situation for both the equipment and human operators of the lining machine.
Accordingly, it would be desirable to provide means for dampening the vibration of the system during the spinning operation for the safety of the machine and its operators.
SUMMARY OF THE INVENTION
According to one embodiment of the invention, a pipe lining machine including several belt assemblies for supporting a pipe to be rotated is provided. The pipe lining machine also includes a base, a drive motor, and several connecting arms for each belt assembly. The connecting arms are connected at a bottom end to the base. At least one of the connecting arms per belt assembly is hingeably connected to the base. Each belt assembly includes several pulleys, each connected to the top end of each of the connecting arms. The pulleys include a drive pulley operatively connected to the drive motor and a movable pulley connected to the connecting arm hingeably connected to the base. A belt formed into a belt loop is wound around the pulleys. An interior surface of the belt loop contacts the pulleys and an exterior surface of the belt loop supports a pipe to be rotated. Means are provided for damping movement of the movable pulley.
According to another embodiment, the means for damping movement of the moveable pulley is a damping assembly operatively coupled to the moveable pulley. Preferably, the damping assembly includes a pneumatic suspension member, e.g., an air bellows, coupled to the moveable pulley, and a hydraulic damping member, e.g., a hydraulic cylinder, coupled to the moveable pulley and to the pneumatic suspension member.
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patent: 5511650 (1996-04-01), Hurworth
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patent: 5763004 (1998-06-01), Hammen
patent: 1275281 (1968-08-01), None
Ameron International, Corp.
Christie Parker & Hale LLP
Edwards Laura
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