GB2150050A

GB2150050A - Pipe coating apparatus

Info

Publication number: GB2150050A
Application number: GB08331142A
Authority: GB
Inventors: Alan Joseph Cole; Peter John Franklin
Original assignee: SPRACON INTERNATIONAL Ltd
Current assignee: SPRACON INTERNATIONAL Ltd
Priority date: 1983-11-22
Filing date: 1983-11-22
Publication date: 1985-06-26
Also published as: GB8331142D0; GB2150050B

Abstract

Pipe coating apparatus comprising a carriage 1 movable within a pipe to be coated by means of a pneumatic drive motor 33 and comprising a rotary atomizer provided with an internally tapered atomizer member 63. <IMAGE>

Description

SPECIFICATION Pipe coating apparatus This invention relates to pipe coating apparatus for applying protective and/or resistant coatings to the inside walls of pipes.

The pipes could be of any material, for example, metal such as steel or ductile iron, or asbestos/cement or a plastics material and the medium to be carried by the pipes could again be varied, for example, oil, gas, chemicals, aviation fuel, fresh water, salt water, sewage or other liquids or gases.

The coatings to be applied could be paint or other materials and high build coatings which are currently used for pipe linings fall into two categories, epoxy coatings and urethane coatings. Within these two categories there are numerous variations, the most difficult to apply being the "solvent free" variety which has a 100% solids content.

It has previously been known to apply pipe coatings by manually pushing or pulling apparatus through a pipe which is provided with a spraying device in the form of a flat spinning disc. A disadvantage with this equipment however is that the manual operation leads to uneven coatings and it cannot apply high build coatings or give controlled film thickness.

The present apparatus is intended to overcome the difficulties referred to above.

According to the present invention pipe coating apparatus comprises a wheeled carriage adapted to be located within a pipe to be coated, drive means for driving the carriage and a coating device carried on said carriage to move therewith and comprising a rotary atomizer provided with an internally tapered atomizer member, means for supplying coating material to the inner surface of the atomizer member, and drive means for rotating the atomizer member to cause coating materials supplied thereto to pass along the internally tapered inner surface thereof and leave the outer periphery as a spray for application onto the inner surface of the pipe with which the apparatus is to be used.

The use of power drive means for moving the carriage enables a predetermined rate of movement to be applied so as to provide a controlled film thickness of coating and the internally tapered atomizer member enables high flow rates and high viscosity coatings to be employed.

Preferably means are included for centrally locating the movable carriage within the pipe to be coated and means may also be included for adjusting the carriage to fit pipes of different diameters.

Preferably the rotary atomizer includes a delivery portion to which coating material is supplied and from which it exits centrifugally onto the inner surface of the atomizer member, said delivery member having an internal taper which is less than the taper on the inner surface of the atomizer member.

The delivery portion can be formed as a conical surface within a delivery member, and the coating material can be arranged to exit therefrom through radially directed slots at the wider end of the conical surface.

This construction enables a smooth flow to be achieved in the atomizer member.

The atomizer member is preferably secured to the delivery member and rotates therewith and the coating material can be supplied to the delivery portion through a stationary delivery orifice.

The angle of the inner surface of the rotary atomizer can be between 306 and 45 to the axis of rotation thereof and in one preferred arrangement the angle is 36 .

Again, the angle of the internal taper of the delivery portion can be between 3 and 15 to the axis of rotation thereof.

The drive means for the rotary atomizer may conveniently comprise a pneumatic motor, and a pneumatic motor may also be employed as the drive means for the carriage.

In a preferred embodiment the movable carriage comprises three or more retractable location assemblies each of which has longitudinally spaced apart wheels, and means for resiliently biasing the location assemblies towards their extended portions.

The resilient biasing may be adjustable to allow the carriage to be used in pipes of different diameters and in a convenient construction the movable carriage includes a central component on which the coating device is carried and to which the retractable assemblies are linked.

The hinges between the central component and the retractable assemblies may include parallel motion linkages and in one preferred construction two or more sets of liinkage arms of different lengths which can be substituted in the parallel motion linkages are included to provide adjustment for pipes of different diameters.

The invention can be performed in many ways but one embodiment will now be described by way of example and with reference to the accompanying drawings in which: Figure 1 is a side elevation of pipe coating apparatus according to the invention: Figure 2 is an end elevation of the apparatus shown in Figure 1 in position in a pipe to be coated; Figure 3 shows an alternative link to be used in the apparatus shown in Figure 1; Figure 4 is a cross-sectional elevation of the coating device; and, Figure 5 is a diagram of the drive means for the apparatus.

As shown in the drawings the pipe coating apparatus comprises a movable carriage 1 which is adapted for location within a pipe to be coated and which comprises a central component 2 formed from a tube 3. The tube 3 is closed at one end by a plug member 4 which has a screw threaded bore 5 in which a threaded rod 6 is located. The threaded rod 6 extends freely through a cylindrical block 7 which is also located within the tubular member 3. Rigidly secured to the threaded rod 6 is a spring retainer 8 which acts against a coil spring 9. One end of the coil spring bears against the spring retainer 8 and the other end bears against the cylindrical block 7.

The cylindrical block 7 is secured to a yoke 10 which surrounds the tube 3 and which is secured to the block 7 by screws 11 which extend through slots 12. The arrangement is such that the spring 9 biases the yoke 10 to a position in which the screws 11 are at the end 13 of the slots 12. The length of the spring is such however that when fully extended and with the threaded member 6 wound back intermediate positions of the screws 11 in the slots 12 can be achieved as shown in Figure 1 in which the screw is at a midway position in the length of the slot.

Two fixed yokes 14 and 15 are also secured to the tube 3, the fixed yoke 14 being at the end adjacent the plug member 4 and the fixed yoke 15 being towards the other end of the tube 3. Each of the yokes has three projecting bifurcated arms 16. The arms 16 on the yoke 14 each carry a link member 17 which is pivoted to the yoke by a pivot pin 18.

Each of the arms 16 on the fixed yoke 15 carry a control link member 19 which is pivoted to the appropriate arms 16 by a pivot pin 20 and each of the arms 16 on the sliding yoke 10 are connected by pivot pins 21 to an operating link 22.

The outer ends of the links 17 and 19 are connected by pivot pins 22 and 23 to an outrigger member 24. Thus there are three outrigger members 24 but, for the sake of clarity, only two are shown in Figure 1 of the drawings.

The outer ends 25 of the operating links 22 are of reduced thickness and are located in slots 26 in the linkage members 19 where they are pivoted by pivot pins 27.

Each of the outriggers 24 is provided with four pairs of wheels 30 the outer rims of the wheels being profiled, as shown in Figure 2, to adapt them to sit snugly within a piipe when inserted therein.

One of the outriggers 24, indicated herein by references numeral 24a, carries the drive means and thus, this outrigger is provided with an extension 31 on which is a clamp 32 which locates and retains a forward and reverse pneumatically operated drive motor 33.

The drive motor rotates a driving sprocket 34 which drives a first chain 35 which operates on a driven sprocket 36 which is located behind one of the pairs of wheels 30. This wheel is indicated by reference numeral 37.

The sprocket 36 is secured to the axle 38 to which a third sprocket 39 is also secured.

This in turn drives a chain 40 which is located on a fourth sprocket 41 on the axle 42. This axle also carries a fifth sprocket 43 which drives a chain 44 to operate a sixth sprocket 45 carried on axle 46 on which is a seventh sprocket 47 which drives a chain 48 to act on a eighth sprocket 49 which is secured to axle 50. This drive system is shown in diagrammatic form in Figure 5.

In order to operate the movable carriage 1 the screw threaded rod 6 is wound out thus allowing the movable yoke 10 to move the left, as shown in Figure 1, which causes the operating links 22 to retract the links 19 thus reducing the overall size of the carriage. The carriage is then inserted into the pipe to be treated and the threaded rod 6 is screwed inwardly so that the spring 9 is compressed and forces the movable yoke 10 towards the right as shown in Figure 1. This causes the operating links 22 to bear against the links 1 9 and thus expand the overall size of the carriage until the pairs of wheels 20 bear against the inner wall of the pipe. The threaded rod 6 can now be screwed further inwardly until a suitable pressure has been achieved by the spring forcing the pairs of wheels 30 against the surface of the pipe.

It will be seen that the central component provided by the tube member 3 and the various outrigger assemblies provide parallel motion linkages to ensure that the whcels are all parallel to each other whcn they are in position. The spring 9 allows for the wheels to run over slight obstacles and to cope with variations in the pipe diamater. Operation of the motor 33 forwards or backwards causes the drive chain mechanism to drive the assembly forwards or backwards within the pipe. Air is fed to the pneumatic motor by a suitable airline (not shown).

The tubular member 3 carries at one end a high speed pneumatic motor 60 which supplies air to operate a coating device 61. The construction of the coating device 61 is most clearly shown in Figure 3 and comprises a rotary atomizer 62 which has a tapered atomizer member 63 in the form of a bell which rotates at high speed to atomize paint supplied to it. The atomizer bell 63 is secured to a delivery mcmber 64. One end of which is secured to a drive arbor 65. The other end of this drive arbor 65 is secured to the pneumatic motor 61. The member 64 has an internal bore 66 and radially extending slots 67 at its end adjacent the tapered portion of the atomizing bell 63. The internal wall of the delivery member 64 has an internal taper and material to be sprayed is delivered to this conical surface 68 by a stationary delivery tube having a delivery orifice 69.

Thus, the material to be sprayed is delivered to the conical surface 68 of the delivery member 64 from which it exits centrifugally through the slots 67 onto the inner surface of the atomizing bell 63. The internal taper of the surface 68 being less than the taper on the inner surface 70 of the bell 63. The atomizer bell 63 is secured to the member 64 by screws (not shown) and rotates therewith.

The angle of the inner surface of the atomizing bell can be between 30 and 45 to the ax:is of rotation and, as shown in Figure 4, the angle is 36 . The internal taper of the delivery portion on the surface 68 can be between 3 and 154 to the axis of rotation thereof.

As described above the apparatus can be used for pipes of different diameters by adjusting the threaded rod 6. The range of movement is however limited and in order to provide a greater range of diameters additional link members 17 and controlling members 19 of different lengths can be provided.

Such an alternative controlling member 19 is shown in Figure 3. It will be seen that the distance between the connecting hole 73 for the p:ivot pin 23 and the pivot hole 74 for the pivot pin 27 is considerably longer than the distance between the same holes on the member shown in Figure 1. Further alternative lengths of the link are shown in broken lines indicated by refernece numerals 75 and 76.

In order to operate the apparatus the appropriate links 17 and 19 are chosen and placed in position. The screwed rod 60 is now operated to allow the apparatus to be inserted in a pipe and the pneumatic drive motor 33 is actuated to drive the apparatus to the far end of the pipe concerned. It will be appreciated that appropriate pneumatic pipes are provided to operate the pneumatic drive motors 33 and 60 and a pipe line (not shown) connects the rotary atomiizer to a material source. In order to coat the inner surface of the pipe the atomizer and pneumatic motors 33 and 60 are now operated so that the apparatus retreats down the pipe spraying as it goes.

Appropriate take-up means (not shown) are used to take in the various pipes and the apparatus is operated to provide a sufficiently thick coating of the material being sprayed.

Due to the construction of the linkage system and the spring 90 slight variations in pipe diameter are accommodated as are small projections. It will be appreciated that the screwed rod 60 is tightened sufficiently to cause the necessary spring pressure to act against the wheels 30 so that there is sufficient grip for the drive and to maiintain the rotary atomizer substantially central within the pipe.

Claims

1. Pipe coating apparatus comprising a movable carriage adapted for location within a pipe to be coated, drive means for driving the carriage and a coating device carried on said carriage to move therewith and comprising a rotary atomizer provided with an internally tapered atomizer member, means for supplying coating material to the inner surface of the atomizer member, and drive means for rotating the atomizer to cause coating materials supplied thereto to pass along the internally tapered inner surface thereof and leave the outer periphery as a spray for application onto the inner surface of the pipe with which the apparatus is to be used.

2. Pipe coating apparatus as claimed in claim 1 including means for centrally locating the movable carriage within the pipe to be coated.

3. Pipe coating apparatus as claimed in claim 1 or claim 2 including means for adjusting the carriage to fit pipes of different diameters.

4. Pipe coating apparatus as claimed in claims 1. 2 or 3 in which the rotary atomizer includes a delivery portion to which coating material is supplied and from which it exits centrifugally onto the inner surface of the atomizer member, said delivery portion having an internal taper which is less than the taper on the inner surface of the atomizer member.

5. Pipe coating apparatus as claimed in claim 4 in which the delivery portion is formed as a conical surface within a delivery member, and the coating material exits therefrom through radially directed slots at the outer end of the conical surface.

6. Pipe coating apparatus as claimed in claim 5 in which the atomizer member is secured to the delivery member and rotates therewith.

7. Pipe coating apparatus as claimed in claim 5 or claim 6 in which the coating material is supplied to the delivery portion through a stationary delivery orifice.

8. Pipe coating apparatus as claimed in any one of claims 1 to 7 in which the angle of the inner surface of the rotary atomizer is between 306 and 45 to the axis of rotation thereof.

9. Pipe coating apparatus as claimed in claim 8 in which the angle is 36 .

10. Pipe coating apparatus as claimed in any one of claims 2 to 7 in which the angle of the internal taper of the delivery portion is between 3 and 15 < to the axis of rotation thereof.

Ii. Pipe coating apparatus as claimed in any one of claims 1 to 10 in which the drive means for the rotary atomizer includes a pneumatic motor.

12. Pipe coating apparatus as claimed in any one of claims 1 to 11 in which the drive means for the carriage includes a pneumatic motor.

13. Pipe coating apparatus as claimed in any one of claims 1 to 12 in which the movable carriage comprises three or more retractable location assemblies each of which has longitudinally spaced apart wheels and means for resiliently biasing the location assemblies towards their extended positions.

14. Pipe coating apparatus as claimed in claim 13 in which the resilient biasing can be adjusted to allow the carriage to be used in pipes of different diameters.

15. Pipe coating apparatus as claimed in claim 13 or claim 14 in which the movable carriage includes a central component on which the coating device is carried, and to which the retractable assemblies are linked.

16. Pipe coating apparatus as claimed in claim 15 in which the hinges between the central component and the retractable assemblies include parallel linkages.

17. Pipe coating apparatus as claimed in claims 13 to 16 including two or more sets of linkage arms of different lengths which can be substituted in the parallel motion linkages to provide adjustment for pipes of different dimensions.

18. Pipe coating apparatus substantially as described herein with reference to and as shown on the accompanying drawings.