Information
-
Patent Grant
-
6174125
-
Patent Number
6,174,125
-
Date Filed
Wednesday, September 29, 199924 years ago
-
Date Issued
Tuesday, January 16, 200123 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Bryant; Joy L.
- Singer; Bart A.
-
CPC
-
US Classifications
Field of Search
US
- 294 93
- 294 981
- 414 618
- 414 7465
- 414 910
-
International Classifications
-
Abstract
The present invention is directed towards a method for racking or unracking pipe to or from a rack and a device to facilitate the process. The method provides a controllable procedure for inserting or withdrawing the pipe that is less dangerous than prior art methods and does not damage the pipe end. The method entails inserting a pipe gripper having an expansion sleeve into an accessible end of a pipe. The expansion sleeve is forced against an inner wall of the pipe, coupling the pipe gripper to the pipe. Depending upon the application, the pipe is then either pushed fully onto the rack or is pulled partially off the rack. For unracking operations, a crane sling is attached to the partially unracked pipe and the pipe is further manipulated off the rack.
Description
FIELD OF THE INVENTION
The present invention relates to racking and unracking a pipe. In particular, it relates to a method and apparatus for racking and unracking pipe wherein the apparatus has an expansion sleeve.
BACKGROUND OF THE INVENTION
As shown in
FIG. 1
, pipes
100
are often warehoused in tiered racks
110
. Three tiers are shown in
FIG. 1
, but pipe racks having five or more tiers are common in practice. Typically, the warehouse will have an overhead crane for moving the pipes. However, wrapping a crane sling around a pipe
100
disposed in a rack
110
is difficult, especially if the pipe
100
is not located on the top tier. Therefore, it is necessary to partially withdraw the pipe
100
from the rack
110
before the crane sling is wrapped around it. Prior methods of accomplishing this task were dangerous and often resulted in damage to an end of the pipe
100
.
The present invention eliminates these drawbacks by providing a controllable means for withdrawing the pipe and reducing the possibility of damage to the pipe. The present invention also provides a useful means for inserting a pipe into a rack with minimal risk of damaging the pipe. A number of prior inventions disclose mechanisms for gripping and manipulating tubular structures, but none will perform satisfactorily when used to rack or unrack pipe.
Cullen et al. (U.S. Pat. No. 4,687,244) describe a lifting and reorienting mechanism. The device includes a probe for insertion into an axially extending opening of a structure to be moved. When fully inserted, movement of an outer sleeve deploys tooth-like retractable projections that extend radially from the probe. The retractable projections are forced against the inner wall of the structure to be moved. An important feature of the Cullen et al. device is a dual-arm telescoping actuator that facilitates pivoting of the probe and the structure to be moved. Although this device is capable of performing many useful functions, it is not well suited for the racking and unracking of pipes. The pivoting capability of the device is not required for pipe racking and unracking and might pose a safety hazard should it be accidentally activated. In addition, the retractable projections of the device are likely to damage the inner surface of the pipe.
Marzoli (U.S. Pat. No. 4,777,792) discloses a tube gripping device that is designed to be used in textile machines to automatically replace with empty tubes those tubes that have been wrapped with yarn. The gripping device comprises a substantially cylindrical central steel element that has its lower end of frusto-conical shape and is free to slide axially in a cylindrical gripping element. The cylindrical gripping element has its bottom shaped to receive the lower end of the cylindrical steel element. An axial upward movement of the cylindrical central element forces a localized region of the cylindrical gripping element radially outward, thereby pressing that region of the cylindrical gripping element against the inner wall of the tube. The radially outward movement of the cylindrical gripping element is localized in the vicinity of the frusto-conical lower end of the cylindrical central element. In addition, the radial motion is a direct response to the radial component of the force exerted on the cylindrical gripping element by the frusto-conical lower end of the cylindrical central element. The localized nature of the gripping force is not desirable for the pipe racking and unracking application being considered herein.
Mistrater et al. (U.S. Pat. No. 5,322,300) describe several variants of a device for supporting hollow cylinders while they are coated with an electrophotographic-imaging layer. The devices comprise an elongated arm with a shaft extending therethrough. The shaft includes a presser means at one end. An expandable disk shaped member is coaxially aligned with and slidably mounted on the shaft between the presser means and an end of the elongated arm. In an undeformed state, the expandable disk shaped member fits in a hollow cylinder with a preferred clearance of about 250 micrometers (0.01 in). Expansion of the disk shaped member is achieved by compressing the member between the presser means and the end of the elongated arm. Additional features of the Mistrater et al. device ensure that a constant force is applied to the hollow cylinder in spite of temperature variations. However, the Mistrater et al. device fails to provide a means for self-orienting the device coaxially with the hollow cylinder.
SUMMARY OF THE INVENTION
The present invention includes a method for racking and unracking pipe and a device to facilitate the process. For the case in which a pipe needs to be removed from a rack (unracking), the method involves providing a pipe gripper having an expansion sleeve and inserting the pipe gripper into an accessible end of a pipe. After insertion, the pipe gripper is activated, thereby forcing the expansion sleeve against an inner wall of the pipe. With the expansion sleeve pressed against the pipe inner wall, the pipe gripper moves so as to slide a portion of the pipe off the pipe rack. With one end of the pipe supported by the pipe gripper and the other end still supported by the pipe rack, a crane sling is attached to the pipe and the pipe is further manipulated off the rack. The use of a forklift coupled to the pipe gripper further facilitates the process. The new method eliminates the dangerous conditions of prior unracking methods and also avoids the need to repair pipe ends.
The case in which a pipe is to be inserted onto a rack (racking) is similar to the unracking process. In the racking process, a pipe that is supported in a crane sling is manipulated so as to place a first end of the pipe on the rack. A pipe gripper having an expansion sleeve is inserted into an accessible end of the pipe and the crane-sling support is removed. The pipe gripper is activated, thereby forcing the expansion sleeve against an inner wall of the pipe and the pipe gripper then moves so as to slide the pipe fully onto the pipe rack. To facilitate the processes, a sophisticated pipe gripper is used. The pipe gripper comprises an expansion sleeve having a distal end a proximal end, and a bore therethrough. A proximal pressure plate abuts the proximal end of the expansion sleeve. A nosepiece is located at the distal end of the expansion sleeve. The nosepiece assists in orienting the pipe gripper coaxially with a pipe to be gripped. A mandrel passes through the bore of the expansion sleeve and is attached to the nosepiece. Tension in the mandrel axially squeezes the expansion sleeve between the nosepiece and the proximal pressure plate. The squeezing forces a radial expansion of the expansion sleeve against an inner wall of the pipe. When pressed against the inner wall of the pipe, the expansion sleeve frictionally couples the pipe to the pipe gripper, thereby allowing the pipe to be moved along its axis.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be obtained by means of instrumentalities in combinations particularly pointed out in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings illustrate a complete embodiment of the invention according to the best modes so far devised for the practical application of the principles thereof, and in which:
FIG. 1
shows pipes in a three-tiered pipe rack.
FIG. 2
shows a preferred embodiment of a pipe gripper in its deactivated mode.
FIG. 3
illustrates a pipe gripper coupled with a forklift.
FIG. 4
displays a preferred embodiment of a pipe gripper after being activated.
FIG. 5
shows a forklift in position to insert a pipe gripper into a pipe on a rack.
FIG. 6
displays a forklift and pipe gripper supporting an end of a pipe and a crane sling wrapped around the middle portion of the pipe.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, where similar elements are numbered the same,
FIG. 2
illustrates a pipe gripper
130
in its deactivated mode. The pipe gripper
130
comprises an expansion sleeve
140
having a bore
141
therethrough. The expansion sleeve
140
is preferably made from an elastomeric substance, which most preferably has a durometer value ranging from about 70 to about 80. All durometer values reported herein use Shore A. The proximal end
146
of the expansion sleeve
140
abuts against a proximal pressure plate
150
. The distal end
144
of the expansion sleeve
140
is preferably shaped to have an external bevel
148
. A mandrel
180
, having a proximal end
182
and a distal end
184
passes through the bore
141
in the expansion sleeve
140
. The distal end
184
of the mandrel
180
extends beyond the distal end
144
of the expansion sleeve
140
and is attached to a nosepiece
170
. In preferred embodiments, the distal end
184
of the mandrel terminates in an endcap
188
embedded in the nosepiece
170
. In some embodiments the endcap
188
is integral with the mandrel
180
, although in other embodiments the endcap
188
is a separate piece that is secured to the mandrel
180
. Because the radius of the endcap
188
is greater than that of the adjacent portion of the mandrel
180
, the nosepiece
170
is securely attached to the mandrel
180
in this preferred embodiment.
The preferred nosepiece
170
has an external shape that is generally cylindrical near its base
174
changing to generally conical near its tip
172
. Preferably, the tip
172
is rounded and the base
174
has an internal bevel
176
. The internal bevel
176
of the base
174
is angled to mate with the external bevel
148
of the distal end
144
of the expansion sleeve
140
. As will be discussed in more detail later, the mating beveled portions of the nosepiece
170
and the expansion sleeve
140
control the bulging of the expansion sleeve
140
when it is axially compressed. Preferably the nosepiece
170
is made from an elastomeric substance with a durometer value of approximately 90.
In the most preferred embodiments of the pipe gripper
130
, a distal pressure plate
160
is secured to the mandrel
180
in the region where the nosepiece
170
and the expansion sleeve
140
meet. As shown in
FIG. 2
, the mandrel
180
preferably includes a flare
186
adjacent to the distal pressure plate
160
. As with the endcap
188
, the flare
186
and the distal pressure plate
160
can be either integral with the mandrel
180
or separate pieces that are secured to the mandrel
180
.
In operation, the nosepiece
170
and the expansion sleeve
140
of the pipe gripper
130
are inserted into a pipe. Preferred embodiments include a limiter that limits the axial motion of the pipe gripper
130
. The term “limiter” is intended to include devices such as sophisticated electronic sensors coupled in a feedback loop with the source of axial motion. In the most preferred embodiments (shown in
FIGS. 2
,
4
,
5
, and
6
) the limiter
200
is a bumper pad coupled to the proximal pressure plate
150
. Contact of the bumper pad
200
with an end of a pipe prevents further insertion of the pipe gripper
130
into the pipe. In the most preferred embodiments, the bumper pad
200
is a radial extension of the proximal pressure plate
150
, both pieces being fabricated as a single integral piece of material. The proximal pressure plate
150
is an annular portion of the material contacting the expansion sleeve
140
while the bumper pad
200
extends outside of the region of contact with the expansion sleeve
140
. Most preferably the material is made of an elastomer with a durometer value ranging from about 85 to about 95. In other embodiments the bumper pad
200
is not disposed in the same plane as the proximal pressure plate
150
. Such an arrangement would be preferable if deeper insertion of the expansion sleeve
140
into the pipe were desired. Although the coupling between the bumper pad
200
and the expansion sleeve
140
is indirect, their spatial relationship determines how deeply the expansion sleeve
140
can be inserted into the pipe.
With reference again to
FIG. 2
, in the preferred embodiments, the pipe gripper
130
includes an actuator
210
, a transmission
230
, and a retaining device shown here as a quick-change retainer pin
220
. The quick-change retainer pin
220
couples the proximal end
182
of the mandrel
180
to the transmission
230
. The transmission
230
transforms and transmits the motion of the actuator
210
into axial motion of the mandrel
180
.
Preferably, the retaining device allows the assembly that includes the mandrel
180
, the expansion sleeve
140
, and the nosepiece
170
(as well as any parts secured thereto) to easily disconnect from the transmission
230
and be replaced with a new assembly that is sized for a different diameter pipe. The use of a quick-change retainer pin
220
as the retaining device facilitates rapid removal and attachment of the assembly. Whether or not the proximal pressure plate
150
and the bumper pad
200
are also exchanged when a newly sized assembly is put in place depends on the arrangement itself. Exchange of the material used for the proximal pressure plate
150
and the bumper pad
200
is dependent in part upon the size of the material and whether the proximal pressure plate
150
is secured to the expansion sleeve
140
or simply abuts against it.
In the most preferred embodiments the transmission
230
comprises a vertical link
238
connected to the actuator
210
, a horizontal link
236
coupled to the mandrel
180
through the use of the quick-change retainer pin
220
, and a bell crank
232
. One lever arm of the bell crank
232
is coupled to the vertical link
238
and the other lever arm of the bell crank
232
is coupled to the horizontal link
236
. In this arrangement, vertical motion from the actuator
210
is transformed to horizontal motion and transmitted to the mandrel
180
.
The most preferred embodiments include a housing
250
, which is coupled to the proximal pressure plate
150
. Most preferably, the proximal pressure plate
150
and the bumper pad
200
simply abut against a portion of a housing
250
. In addition, the housing
250
most preferably provides an opening
252
for the mandrel
180
to pass therethrough and an opening
251
for the transmission
230
. Support for the axis of the bell crank
232
is not shown, but the design of such a support is straightforward to those skilled in the art.
A forklift bracket
260
is also included in the most preferred embodiments. In the embodiment illustrated in
FIG. 2
, the actuator
210
is supported by a flange
211
of the forklift bracket
260
.
FIG. 3
shows the pipe gripper
130
attached to a forklift
270
through the forklift bracket
260
. Most preferably, a standard side-shifting forklift is used. In particular, the pipe gripper
130
is intended to be coupled with the Model H60XM 3-ton forklift built by the Hyster Company. This forklift
270
can deliver hydraulic pressure to attachments, therefore the use of a hydraulic actuator
210
is preferred.
The principles involved in the operation of the pipe gripper
130
are easily surmised through a comparison of the pipe gripper
130
in its undeployed and deployed states in
FIGS. 2 and 4
, respectively. In the undeployed state in
FIG. 2
, the expansion sleeve
140
has a substantially constant radius along its length (except for the external bevel
148
at its distal end
144
). To deploy the pipe gripper
130
, the actuator
210
draws the vertical link
238
upward, thereby rotating the bell crank
232
about its axis and pulling the horizontal link
236
. This applies a tension to the mandrel
180
, thereby pulling the nosepiece
170
and the distal pressure plate
160
toward the proximal pressure plate
150
. This action compresses the expansion sleeve
140
axially, which results in a radial bulging of the expansion sleeve
140
, as shown in FIG.
4
. Reversing the process allows the expansion sleeve
140
to return to its original shape.
In the embodiment of
FIGS. 2 and 4
, both the nosepiece
170
and the distal pressure plate
160
exert compressive forces on the distal end
144
of the expansion sleeve
140
. In some other embodiments, only the distal pressure plate
160
exerts a compressive force on the distal end
144
of the expansion sleeve
140
, and in still other embodiments, only the nosepiece
170
exerts a compressive force on the distal end
144
of the expansion sleeve
140
. In embodiments in which the base
174
of the nosepiece
170
is beveled, the angle of the bevel controls the bulging of the expansion sleeve
140
. Large bevel angles tend to direct the bulging to the middle portion of the expansion sleeve
140
while small bevel angles (or no bevel) often lead to somewhat increased bulging at the proximal
146
and distal
144
ends of the expansion sleeve
140
. When used to grip a pipe, the radial bulging of the expansion sleeve
140
forces the expansion sleeve
140
against an inner wall of the pipe. Large frictional forces between the expansion sleeve
140
and the pipe allow the pipe to be pushed or pulled by the pipe gripper
130
.
Although the pipe gripper embodiments described above are preferred, the main feature of the pipe gripper is that it has an expansion sleeve that can be forced outward into engagement with an inner wall of a pipe.
FIGS. 5 and 6
show a preferred embodiment of a new pipe unracking method that employs the pipe gripper
130
described above. A pipe
100
is stored on a rack
110
. A pipe gripper
130
is shown coupled to a forklift
270
. In
FIG. 5
, the expansion sleeve
140
and the nosepiece
170
of the pipe gripper
130
are shown. Preferably a variety of differently sized expansion sleeves
140
can be installed on the pipe gripper
130
. The expansion sleeve
140
chosen is sized to fit inside the pipe
100
with little clearance. With the appropriate expansion sleeve
140
installed, the operator uses the forklift
270
to insert the pipe gripper
130
into an accessible end
102
of the pipe
100
. The inclined sides of the nosepiece
170
help to self-orient the pipe gripper
130
coaxially with the pipe
100
. Interaction of the nosepiece
170
and the pipe
100
tend to push the nosepiece
170
and expansion sleeve
140
into alignment with the pipe
100
. This allows the operator to easily make minor adjustments to the position of the pipe gripper
130
during initial insertion. When the position is correct, the operator moves the forklift
270
forward until the bumper pad
200
contacts the accessible end
102
of the pipe
100
.
After the pipe gripper
130
is fully inserted in the pipe
100
, the expansion sleeve
140
of the pipe gripper
130
is forced outward against an inner wall of the pipe
100
. For example, compressive forces on the distal and proximal ends of the expansion sleeve
140
cause radial bulging, thereby forcing the expansion sleeve
140
against the inner wall of the pipe
100
. The friction force between the expansion sleeve
140
and inner wall of the pipe
100
allows the pipe to be slid partially off the rack by reversing the direction of the forklift
270
.
Referring to
FIG. 6
, when the center of gravity
104
of the pipe
100
is clear of the pipe rack
110
, a crane sling
124
is attached to the pipe
100
. In this embodiment, the crane sling
124
is supported by an overhead crane
120
via a crane hook
122
. In other embodiments, a truck-mounted crane, or any device suitable for supporting the crane sling
124
, is substituted for the overhead crane
120
. Also not shown in the figure is an alternate embodiment wherein the accessible end
102
of the pipe
100
is raised slightly by the pipe gripper
130
, thereby permitting the crane sling
124
to be manipulated into position with less of the pipe withdrawn from the rack
110
. This mode of operation is useful under certain circumstances. Referring again to
FIG. 6
, with the weight of the pipe
100
supported primarily in the crane sling
124
, the pipe
100
is manipulated off the rack
110
. The pipe gripper
130
is removed from the pipe
100
after releasing the compressive forces that forced the expansion sleeve
140
to bulge outward. Depending upon the circumstances, the pipe gripper
130
is removed from the pipe
100
either before or after the pipe
100
is fully off the rack
110
. However, the pipe gripper
130
is not removed until after the weight of the pipe
100
is substantially supported in the crane sling
124
. After the pipe
100
is clear of the rack
110
, the overhead crane
120
, or an appropriate substitute transports it.
A method for racking pipe onto a pipe rack
110
is similar to the unracking process described above practiced in reverse. With reference to
FIGS. 6 and 5
, in the racking process, a pipe that is supported in a crane sling
124
is manipulated so as to place a first end of the pipe
100
on the rack
110
. A pipe gripper
130
having an expansion sleeve
140
sized to fit in the pipe
100
is inserted into an accessible end
102
of the pipe
100
. Preferably, insertion continues until the accessible end
102
of the pipe
100
contacts the bumper pad
200
. After insertion, the pipe
100
is supported at the first end by the rack
110
and at the accessible end
102
by the pipe gripper
130
. In this configuration, the support that is provided by the crane sling
124
is unnecessary and generally undesirable, so the crane-sling support is removed. Preferably, the crane-sling support is removed by lowering the height of the crane sling
124
, thereby removing any pressure that the crane sling
124
might apply to the pipe
100
. Alternatively, the crane-sling support is removed by completely removing the crane sling
124
from around the pipe
100
. However, the preferred approach is more desirable because in it, the crane sling
124
can rapidly resupport the pipe
100
if an emergency situation develops. Either before or after removal of the crane-sling support, but after insertion of the pipe gripper
130
, the pipe gripper
130
is activated, thereby forcing the expansion sleeve
140
against an inner wall of the pipe
100
. With the expansion sleeve
140
pressed against the pipe inner wall, the pipe gripper
130
then moves so as to slide the pipe
100
fully onto the pipe rack
110
. The pipe
100
is considered to be fully on the pipe rack
110
when the pipe gripper
130
can be removed from the pipe
100
without the pipe
100
falling from the rack
110
. With the pipe
100
fully on the rack
110
, the pipe gripper
130
is removed from the pipe
100
. As with the unracking process, coupling a forklift
270
to the pipe gripper
130
greatly facilitates movement of the pipe gripper
130
.
The above description and drawings are only illustrative of preferred embodiments which achieve the objects, features and advantages of the present invention, and it is not intended that the present invention be limited thereto. Any modification of the present invention that comes within the spirit and scope of the following claims is considered part of the present invention.
Claims
- 1. A pipe gripper, comprising:an expansion sleeve having a distal end, a proximal end, and a bore the therethrough; a proximal pressure plate abutting the proximal end of said expansion sleeve; a nosepiece at the distal end of said expansion sleeve; a mandrel passing through the bore of said expansion sleeve, said mandrel having a proximal end and a distal end, the distal end being attached to said nosepiece; a distal pressure plate at the distal end of said expansion sleeve, said distal pressure plate being coupled to said mandrel such that pulling the proximal end of said mandrel axially compresses said expansion sleeve between said distal pressure plate and said proximal pressure plate; wherein pulling the proximal end of said mandrel causes both said nosepiece and said distal pressure plate to exert compressive forces on the distal end of said expansion sleeve; and wherein the distal end of said expansion sleeve has an external bevel and said nosepiece has an internal bevel for receiving the external bevel of said expansion sleeve.
- 2. A pipe gripper, according to claim 1, further comprising:a bumper pad coupled to said proximal pressure plate.
- 3. A pipe gripper, according to claim 2, further comprising:an actuator; a transmission; and a quick-change retainer pin; said quick-change retainer pin coupling the proximal end of said mandrel to said transmission, said transmission transforming and transmitting motion from said actuator into axial motion of said mandrel.
- 4. A pipe gripper, according to claim 3, further comprising:a housing coupled to said proximal pressure plate; a forklift bracket secured to said housing; and a forklift, said forklift bracket being attached thereto.
- 5. A pipe gripper, according to claim 4, wherein said expansion sleeve has a Shore A durometer value ranging from about 70 to about 80.
US Referenced Citations (11)