GB2250456A

GB2250456A - Tube finning apparatus

Info

Publication number: GB2250456A
Application number: GB9022089A
Authority: GB
Inventors: Michael Pollitt; Stephen Bell
Original assignee: ADVANCED COMBUSTION ENG
Current assignee: ADVANCED COMBUSTION ENG
Priority date: 1990-10-11
Filing date: 1990-10-11
Publication date: 1992-06-10
Anticipated expiration: 2010-10-11
Also published as: GB9022089D0; GB2250456B; WO1993012900A1

Abstract

A tube finning apparatus comprising a fin wrapping head 7 for dispensing a band of finning material 8 onto a rotating tube 3. The head is arranged to dispense the finning material onto the tube in a manner such that a force is transmitted to the head by the finning material in a direction parallel to the tube length. The head is mounted so as to be readily displaceable along the length of the tube. The head may be mounted on a trolley supported on a portable table. <IMAGE>

Description

TUBE FINNING APPARATUS AND METHOD The present invention relates to a tube finning apparatus and method.

Finned tubing is widely used in various heat-exchange applications, for example central heating radiators, drying machines and air ducting. The conventional finned tube comprises a band of steel which is wrapped in the form of a helix around the tube with the width of the strip extending substantially radially relative to the tube. Tube finning heads are well known which enable the strip of steel to be dispensed under tension so that there is close contact between the radially inner edge of the band and the outer surface of the tube. Such finning heads maintain the radially outer edge of the band in a substantially perfect helix whereas the radially inner edge defines an alternating waveform to accommodate the difference in circumference between the radially outer edge of the band and the surface of the tube.

Traditional tube finning machines comprise a lathe-like structure comprising chucks for supporting opposite ends of the tube to be finned, the chucks being arranged at opposite ends of an elongate bed.

A finning head is mounted on the bed and driven along the length of the bed as finning band is dispensed onto a tube supported by and rotated by the chucks. Generally it is necessary to provide tube lengths of as much as six metres and the length of the bed must be sufficient to accommodate such tube lengths. Accordingly the tube finning apparatus is massive, including a very long and weighty bed.

It is therefore not a practical matter to provide heating engineers with tube finning machines for use on construction sites to manufacture finned tube to meet immediate demands. Accordingly heating engineers requiring finned tube must order their requirements from stockholders. Stockholders maintain stocks of only a limited variety of tube diameters and lengths but are prepared to make nonstandard lengths to suit particular applications. Unfortunately, it is often the case that heating engineers only appreciate exactly what tube lengths they require once they are on site. Thus ordering exstock introduces delays, and even greater delays arise if non-standard lengths are required.

With non-finned tube, heating engineers buy standard lengths and cut these as necessary to meet their immediate requirements. The heating engineers are provided with tube threading machines which can be used on site to enable appropriate connections to be made to the ends of the tubes. It is not possible to simply cut finned tubes to length as is the case with non-finned tube. This is because the finning is secured to the tube by welds, generally two wells, one at each end of the finning on the tube. Even if it was possible to cut through the tube and finning the result would generally be that the finning would uncoil from the tube and would have to be discarded.

In any event finned tube is relatively expensive and the discarding of offcuts would involve substantial extra expense.

It is an object of the present invention to obviate or mitigate the problems outlined above.

According to the present invention there is provided a tube finning apparatus comprising a fin wrapping head adapted to dispense a band of finning material onto a rotating tube, wherein the head is arranged to dispense the finning material onto the tube in a manner such that a force is transmitted to the head by the finning material in a direction parallel to the tube length, and the head is mounted so as to be readily displaceable along the length of the tube.

Preferably, the head is mounted on a trolley. The trolley may be supported on a portable table. The tube may be rotated in any convenient rotating machine, for example a portable screw-threading machine defining a chuck through which a tube may be inserted and gripped.

The present invention also provides a method for dispensing a band of finning material onto a rotating tube, wherein a fin wrapping head is arranged adjacent the rotating tube and positioned to dispense the finning material onto the tube such that a force is transmitted to the head by the finning material in a direction parallel to the tube length, and the head is supported in such a manner as to be readily displaceable along the length of the tube in response to the force transmitted to the head by the finning material.

Thus, in accordance with the present invention it is not necessary to provide a complex and large machine incorporating a bed at least as long as the longest length of pipe to be finned. It is simply necessary to provide a relatively short table, for example 2 metres in length, and to mount on that table a trolley supporting the finning head. A rotating machine such as a screw threading machine may be mounted at one end of the table and a tube may be inserted through the rotating machine and supported at its end above the table by the finning head. The rotating machine is then caused to grip and rotate the tube and the finning head is then propelled along the length of the table as finning material is displaced.Once the finning head reaches the end of the table adjacent the rotating machine, the rotating machine is stopped, the tube is pushed through the rotating machine so as to drive the finning head back to the far end of the table, and the process is then repeated. Thus simple equipment readily transportable to construction sites can be provided which enables heating engineers to fabricate finned tube exactly the required length. It is no longer necessary to order finned tube exstock or in special lengths and the delays and further expense inherent in such procedures are thereby avoided.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side elevation of an embodiment of the present invention; and Figure 2 is a plan view of the embodiment of Figure 1.

Referring to the drawings, a conventional rotating screw threading machine 1 is shown mounted on a table 2. A tube 3 which is to be finned is mounted in the rotating machine 1 and extends above a table defined by sections 4 and 5 through a guide 6 and a finning material dispensing head 7. A coil 8 of finning material is supported on a table 9 adjacent the finning head shown in Figure 2.

The coil 8 and table 9 are not shown in Figure 1.

The table sections 4 and 5 are bolted together at join 10. The table section 4 has legs 11 which rest on the top of table 2 and the table section 5 has legs 12 which rest on the floor. Thus the table section 4 and 5 can be readily transported, assembled and mounted in the illustrated position without undue effort.

The guide 6 and tube finning head 7 are mounted on a trolley 13 which is received within a channel 14 defined in the upper surface of table sections 4 and 5. The trolley 13 is supported on wheels (not shown) and is therefore readily displaceable along the length of the channel.

The dispensing head 7 is of conventional form. When the tube 3 is rotated by the machine 1 the band of finning material is drawn through the dispensing head and wrapped tightly around the tubes.

As a result a substantially helical fin formation 15 is formed on the tube 3. The finning band is of relatively stiff material and accordingly given that the band is dispensed at an angle inclined to the tube axis, as the band is dispensed a force is applied to the head 7 in a direction parallel to the length of the tube 3. This force is sufficient to displace the trolley along the length of the channel.

Thus the tube and the dispensed band operates in effect as a threaded drive screw of the type generally used in machine tools to drive a component along the length of a machine tool bed.

The roll of finning material is preferably supported by being suspended from the trolley 13 so as to move along the length of the tube with the tube finning head.

Each of the table sections 4 and 5 will preferably be relatively short, for example 1 metre in length. If a tube length has to be finned which is longer than the length of the resultant table, the tube is pushed through the chuck of the machine 1 so that one of its ends is adjacent the far end of the table section 5. Finning band is then dispensed, causing the trolley 13 to move along the channel 14 to the end of the table section 4 adjacent the machine 1. Rotation of the tube is then stopped and the tube is released from the chuck of the machine 1 and pushed through the machine so as to drive the trolley 13 back to the far end of the table section from the machine 1. The machine chuck is then re-engaged and further finning band is dispensed onto the tube. Thus any length of tube can be finned despite the fact that the apparatus provided defines what is in effect a relatively short bed.

Most heating engineers are provided on site with a machine for threading tube which can be used as the machine 1 of Figures 1 and 2. Thus all that has to be provided in addition to equipment normally availableis the table sections 4 and 5 and the trolley 13 and its attachments. Heating engineers are thus then provided with all they need to produce finned tubes to exactly the length they require.

Claims

CLAIMS:

1. A tube finning apparatus comprising a fin wrapping head adapted to dispense a band of finning material onto a rotating tube, wherein the head is arranged to dispense the finning material onto the tube in a manner such that a force is transmitted to the head by the finning material in a direction parallel to the tube length and the head is mounted so as to be readily displaceable along the length of the tube.

2. An apparatus according to claim 1, wherein the head is mounted on a trolley.

3. An apparatus according to claim 2, wherein the trolley is supported on a portable table.

4. An apparatus according to any preceding claim, comprising a portable screw-threading machine defining a chuck through which a tube may be inserted and gripped.

5. A method for dispensing a band of finning material onto a rotating tube, wherein a fin wrapping head is arranged adjacent the rotating tube and positioned to dispense the finning material onto the tube such that a force is transmitted to the head by the finning material in a direction parallel to the tube length, and the head is supported in such a manner as to be readily displaceable along the length of the tube in response to the force transmitted to the head by the finning material.

6. A tube finning apparatus substantially as hereinbefore described with reference to the accompanying drawings.