Flexible shoe for a bending machine

A flexible shoe for a bending machine which includes a pair of flexible resilient spring-like shafts. A flexible web extends between and is secured to the pair of shafts.

FIELD OF THE INVENTION 
The present invention relates to a flexible shoe for a bending machine and, 
in particular, pipe bending machines used to bend large diameter pipe for 
oil and gas pipelines. 
BACKGROUND OF THE INVENTION 
Pipe bending machines used to bend large diameter pipe for oil and gas 
pipelines have at least one flexible shoe that engages the pipe and 
accommodates the bending moment. With an end-pull style pipe bending 
machines, a single flexible shoe is positioned on top of the pipe. A sling 
is then used to pull one end of the pipe, thereby forcing the pipe 
upwardly against the flexible shoe. With center-push style pipe bending 
machines three flexible shoes are used; two lower shoes and one upper 
shoes. The two lower shoes support the pipe in spaced relation. The upper 
shoe exerts a downward force between the two lower shoes to bend the pipe. 
The flexible shoes presently consist of a plurality of closely spaced 
parallel arcuate segments. The segments are generally made of metal and 
coated with rubber or urethane, so as not to damage the pipe. An inherent 
problem with such flexible shoes is that they require frequent and costly 
repairs, as tears in the rubber or urethane coating commonly occur and 
recoating is required. 
SUMMARY OF THE INVENTION 
What is required is a flexible shoe that requires less maintenance and is 
less expensive to repair. 
According to the present invention there is provided a flexible shoe for a 
bending machine which includes a pair of flexible resilient spring-like 
shafts. A flexible web extends between the pair of shafts. Means is 
provided for securing the flexible web to the shafts. 
The flexible shoe, as described above, is easy to maintain and inexpensive 
to maintain in comparison with the flexible shoes that consist of a 
plurality of arcuate coated segments. If wear occurs in the flexible web, 
a replacement for the flexible web can be substituted in a matter of 
minutes. The preferred manner of attaching a flexible shoe for a pipe 
bending machine which includes a pair of sleeves secured to the flexible 
web in parallel spaced relation. One of the flexible resilient spring-like 
shafts is disposed in each of the sleeves. There are a variety of ways in 
which the flexible shoe, as described above, can be secured to a flexible 
shoe mounting of a pipe bending machine. It is preferred that each of the 
sleeves have radial slots. Remote ends of the arms of the flexible shoe 
mounting of the pipe bending machine can be inserted through the radial 
slots and then the shafts extended through apertures in the remote ends of 
the arms to secure flexible shoe to the arms. This manner of mounting is 
viewed as being the simplest and most cost effective. 
Although beneficial effects may be obtained through the use of the flexible 
web, as described above, another problem present in the prior art is that 
the pressure exerted by flexible shoes made from segments is mostly on the 
top of the pipe. This uneven pressure results in some "egging" of the pipe 
occurring. Even more beneficial effects may, therefore be obtained when a 
plurality of rollers are mounted on each shaft. The rollers secured as 
they are to the ends of the flexible web, wrap around the pipe and apply 
side pressure. This provides more even pressure and prevents "egging" of 
the pipe from occurring. The rollers also provide a number of secondary 
functions. Depending upon the types of mounting used, they assist with the 
positioning of the pipe. They also increase the surface area over which 
the force is spread. This decreases the pressure exerted per square inch 
upon the flexible web. 
Although beneficial results may be obtained through the use of the flexible 
shoe, as described above, even more beneficial effects can be obtained 
when the flexible shoe is used in combination with a pipe bending machine 
that has a mounting suited to emphasize its advantages. According to 
another aspect of the present invention there is the flexible shoe used in 
combination with a pipe bending machine having a mounting for a flexible 
shoe that includes a support and a first pair of spaced apart mounting 
arms. At least one of the arms is pivotally mounted to the support for 
movement toward and away from the other of the arms. Each of the arms has 
a remote end with an aperture. A second pair of spaced apart arms is also 
provided. At least one of the arms is pivotally mounted to the support for 
movement toward and away from the other of the arms. Each of the arms has 
a remote end with an aperture. The apertures in the second pair of arms 
are in placed in axial alignment with the apertures in the first pair of 
arms. The mounting arms of the pipe bending machine extend through slots 
in the flexible web. The shafts extend through the apertures at the remote 
ends of the arms to couple the sleeves to the arms with the flexible web 
suspended between. This form of mounting with one movable arm helps 
cooperate with the rollers and the flexible web to provide an even 
pressure upon the pipe.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The preferred embodiment, a flexible shoe for a pipe bending machine 
generally identified by reference numeral 10, will now be described with 
reference to FIGS. 1 through 4. 
Referring to FIGS. 1 and 2, flexible shoe 10 is illustrated mounted on a 
unique flexible shoe mounting 12. Shoe mounting 12 is supported by a 
mounting adaptor 14 of conventional construction from a pipe bending 
machine. Flexible shoe mounting 12 is especially adapted to get the best 
results out of the present invention, as will hereinafter be further 
described. Flexible shoe mounting 12 consists of a support 16 which is 
pivotally mounted by means of a pin 18 to mounting adaptor 14. Referring 
to FIG. 1, a first pair of spaced apart mounting arms 20 and a second pair 
of mounting arms 22 are provided. Referring to FIG. 2, mounting arms 20 
are illustrated. It will be understood that although second pair of 
mounting arms 22 are not shown they are identical in construction to first 
pair of mounting arms 20. First pair of mounting arms 20 include a 
stationary arm 24 and a movable arm 26 which is pivotally mounted to 
support 16 for movement toward and away from stationary arm 24. There are 
a number of alternative mounting apertures 27, provided providing a number 
of alternative mounting positions for movable arm 26. Each of first pair 
of arms 20 and second pair of arms 22 have a remote end 28 with an 
aperture 30 extending therethrough. Apertures 30 in second pair of arms 22 
are in axial alignment with apertures 30 in first pair of arms 20. 
Referring to FIGS. 1 and 2, flexible shoe 10 includes an elongate flexible 
fabric web 32 having a first longitudinal sleeve 34 positioned along a 
first side 36 and a second longitudinal sleeve 38 positioned along a 
second side 40. A first flexible resilient spring-like shaft 42 is 
positioned in first longitudinal sleeve 34. A second flexible resilient 
spring-like shaft 44 is positioned in second longitudinal sleeve 38. Three 
flexible tubular rollers 46 extend over each of first shaft 42 and second 
shaft 44. Rollers 46 engage first longitudinal sleeve 34 and second 
longitudinal sleeve 38. Each of first longitudinal sleeve 34 and second 
longitudinal sleeve 38 have a pair of spaced apart slots 48 through which 
first pair of mounting arms 20 and second pair of mounting arms 22 of shoe 
mounting 12 extend. First shafts 42 and second shaft 44 extend through 
apertures 30 at remote ends 28 of first pair of arms 20 and second pair of 
arms 22 to couple first longitudinal sleeve 34 and second longitudinal 
sleeve 38 to first pair of arms 20 and second pair of arms 22 with 
flexible web 32 suspended between stationary arm 24 and movable arm 26. 
Locking Fasteners 50 are placed on remote ends 52 of first shaft 42 and 
second shaft 44 to prevent their removal. In the description which follows 
a pipe will be generally identified by reference numeral 54. 
The use and operation of flexible sleeve 10 will now be described with 
reference to FIGS. 1 through 4. The component parts of flexible shoe 10 
must be assembled in situ onto shoe mounting 12. This is accomplished by 
positioning one of rollers 46 within first longitudinal sleeve 34 and 
extending stationary arm 24 of first pair of arms 20 and stationary arm 24 
of second pair of arms 22 through slots 48. First shaft 42 is then 
extended through apertures 30 at remote ends 28 of stationary arms 24 and 
through roller 46. The other rollers 46 are then placed on either end of 
first shaft 42. Locking fasteners 50 are then placed on remote ends of 
first shaft 42 to prevent rollers 46 from being removed. Of course, this 
also prevents first shaft 42 from being withdrawn from apertures 30. The 
process is repeated on the other side, with one of rollers 46 positioned 
within second longitudinal sleeve 38 and movable arm 26 of first pair of 
arms 20 and movable arm 26 of second pair of arms 22 being extended 
through slots 48. Second shaft 44 is then extended through apertures 30 at 
remote ends 28 of movable arms 26 and through roller 46. The other rollers 
46 are then placed on either end of second shaft 44. Locking fasteners 50 
are then placed on remote ends of second shaft 44 to prevent rollers 46 
from being removed. FIG. 3 illustrates flexible shoe 10 in use on an 
end-pull style of pipe bending machine 15. FIG. 4 illustrates flexible 
shoe 10 in use on a center-push style of pipe bending machine 17. 
Referring to FIG. 2, it is to be noted how flexible shoe 10 wraps around 
pipe 54 with rollers 46 engaging and applying side pressure to pipe 54. 
This enables more even pressure to be applied to prevent pipe 54 from 
"egging". Rollers 46 also help position pipe 54 relative to arms 24 and 
26. Referring to FIGS. 3 and 4, it is to be noted the manner in which 
first shaft 42, second shaft 44 and rollers 46, flex to accommodate the 
bending of pipe 54. First shaft 42, second shaft 44 and rollers 46 are 
both flexible and resilient. They spring back to their original 
configuration when the bending of pipe 54 is completed and pipe 54 is 
withdrawn from flexible shoe 10. Rollers 46 are flexible in order to 
accommodate the movement of spring-like shafts 42 and 44. Rollers 46 must 
also be able to withstand the compression force placed upon them during 
the bending operation. Shoe mounting 12 assists the operation of flexible 
shoe 10. Movable arm 26 works in conjunction with rollers 46 to enable 
rollers 46 to apply greater side pressure than would be possible with a 
fixed mounting. Pivot pin 18 allows shoe mounting 12 to pivot during the 
bending process. The selection of one of mounting apertures 27 for movable 
arm 26 is made depending upon the size of pipe being bent and the amount 
of side pressure required. 
It will be apparent to one skilled in the art the manner in which flexible 
shoe 10 overcomes the disadvantages inherent in the prior art. Flexible 
shoe 10 is easy, quick and inexpensive to maintain. Maintenance on 
flexible shoe 10 is primarily limited to replacement of flexible web 32 
when it becomes worn. Rollers 46 provide side pressure on pipe 54 as it is 
being bent to provide a better quality of bend. A conventional segmented 
flexible shoe is approximately 28 inches in length. Flexible web 32 can be 
made longer (44 inches or more), which also seems to improve the quality 
of the bend. 
It will be apparent to one skilled in the art that modifications may be 
made to the illustrated embodiment without departing from the spirit and 
scope of the invention as hereinafter defined in the Claims.