GB1591366A - Production of currugated fins for packed construction heat exchangers - Google Patents

Description

(54) PRODUCTION OF CORRUGATED FINS FOR PACKED CONSTRUCTION HEAT EXCHANGERS (71) We, BL Cs LIMITED, formerly known as British Leyland UK Limited, a British Company of 35-38 Portman Square, London, formerly of Leyland House, 174 Marylebone Road, London NWl 5AA, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to the production of corrugated fins for packed construction heat exchangers. In such heat exchangers the corrugated fins are sandwiched between flatsection tubes and therewith define substantially triangular-section airways.

A known method of continuously producing corrugated fins from thin (e.g. 0.1 mm) metal strip stock comprises initially forming transverse corrugations in the strip, subsequently subjecting the corrugated strip to lengthwise compression between two pairs of friction belts, moving at differential speed and bearing upon the peaks of the corrugations at opposite sides of the strip, and finally separating the corrugated strip into predetermined lengths.

The lengthwise compression of the corrugated strip overcomes the resilience of the strip and permanently reduces the natural, average pitch angle of the corrugations.

A problem experienced with the known method is a tendency for the pressure imposed by the friction belts on the peaks of the corrugations to deform the corrugations.

Reduction of this pressure is liable to result in slippage between the belts and the strip to an extent that only partial and insufficient lengthwise compression of the strip results.

The problem of controlling the pressure imposed by the belts is made more difficult by the change in "height" of the corrugations that accompanies the change in length of the corrugated strip.

The present invention is concerned with mitigating the above mentioned problems and to this end resides in a method of continuously producing corrugated strip from metal strip stock, comprising the steps of initially forming transverse corrugation in the strip and subsequently subjecting the corrugated strip to lengthwise compression between two pairs of friction belts moving at differential speed, characterised in that the friction faces of the belts are applied to the ends of the corrugations at opposite edges of the strip.

The method according to the invention has the advantage that the belts apply pressure to the strip in the direction that the strip possesses its greatest resistance to deformation. A further advantage is that the corrugated edges of the strip tend to bed into the friction faces of the belts, thus improving the frictional engagement between the belts and the strip and reducing the pressure required to avoid undesirable slippage.

From another aspect the invention resides in apparatus for use in carrying out the method according to the invention, comprising: (a) a support surface adapted to support the strip on the peaks of the cor rugations at one side thereof; (b) first and second pairs of friction belts arranged successively along the sup port surface, the friction faces of each pair of belts being opposed to one another across and in a perpen- dicular relation to the support surface for engaging the opposite edges of the strip; and (c) means for driving the first and second pairs of friction belts at a differential speed, such that the first pair moves faster than the second pair.

Conveniently, at least one friction belt of each pair is supported for displacement, and is spring biased, towards the other belt of the same pair. By this arrangement the pressure imposed by the belts on the strip can be precisely controlled.

A preferred embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a plan view of apparatus for subjecting the corrugated strip to lengthwise compression, and Figure 2 is a cross-section view on the line Il-Il in Figure 1.

Referring to the drawings, a platform 1, having a raised central longitudinal portion 2, supports two pairs of identical belt drives A, B and C, D arranged at opposite sides of the raised portion 2.

Each of the belt drives comprises a notched drive pulley 3, two slave pulleys 4, and a notched belt 5. The pulley 3 is mounted on a sliding block 6 for adjustment of the belt tension by means of a screw clamp 8, and the pulleys 4 are mounted on a separate U-shaped sliding block 7 for adjustment in relation to the raised portion 2 of the platform 1 by means of bolts passing through slots 9. The runs of the belts 5 between the pulleys 4 are parallel to and adjacent to the raised portion 2, and are opposed to one another in the pairs A, B and C, D.

An electric motor (not shown) mounted on the underside of the platform 1 drives the pulleys 3 of the pair A, B at a first speed and also drives, through a speed reduction transmission (not shown), the pulleys 3 of the pair C, D at a second, slower speed.

In operation a corrugated strip is advanced along the surface of the raised portion 2 of the platform 1 by and between the pairs of belt drives A, B and C, D. The opposed surfaces of the belts 5 frictionally engage the corrugated opposite edges of the strip.

Since the belts 5 of the pair A, B are driven faster than those of the pair C, D the corrugations become bunched together as the strip advances between the two pairs A, B and C, D.

As the strip emerges from between the belts 5 of the second pair C, D, the corrugations spring open to assume a reduced pitch angle compared to that present prior to lengthwise compression in the apparatus.

In a modified construction of the preferred apparatus, the belt drives A and C are spring biased towards the belt drives B and D, respectively. More particularly, the slots 9 in the sliding blocks 7 of the belt drive assemblies A and C are replaced by studs which project downwardly through guide slots in the platform 1. The studs are engaged by tension springs anchored to the platform 1, which springs bias the blocks 7 of the drive assemblies A and C towards the assemblies B and D, respectively, for gripping the corrugated strip between the belts 5.

WHAT WE CLAIM IS:- 1. A method of continuously producing corrugated strip from metal strip stock, comprising the steps of initially forming transverse corrugations in the strip and subsequently subjecting the corrugated strip to lengthwise compression between two pairs of friction belts moving at differential speed, characterised in that the friction faces of the belts are applied to the ends of the corrugations at opposite edges of the strip.

2. Apparatus for use in carrying out the method according to Claim 1, comprising: (a) a support surface adapted to support the strip on the peaks of the cor rugations at one side thereof; (b) first and second pairs of friction belts arranged successively along the sup port surface, the friction faces of each pair of belts being opposed to one another across and in a perpen dicular relation to the support surface for engaging the opposite edges of the strip; and (c) means for driving the first and second pairs of friction belts at a differential speed, such that the first pair moves faster than the second pair.

3. Apparatus according to Claim 2, in which at least one friction belt of each pair is supported for displacement, and is spring biased, towards the other belt of the same pair.

4. Apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. Figure 1 is a plan view of apparatus for subjecting the corrugated strip to lengthwise compression, and Figure 2 is a cross-section view on the line Il-Il in Figure 1. Referring to the drawings, a platform 1, having a raised central longitudinal portion 2, supports two pairs of identical belt drives A, B and C, D arranged at opposite sides of the raised portion 2. Each of the belt drives comprises a notched drive pulley 3, two slave pulleys 4, and a notched belt 5. The pulley 3 is mounted on a sliding block 6 for adjustment of the belt tension by means of a screw clamp 8, and the pulleys 4 are mounted on a separate U-shaped sliding block 7 for adjustment in relation to the raised portion 2 of the platform 1 by means of bolts passing through slots 9. The runs of the belts 5 between the pulleys 4 are parallel to and adjacent to the raised portion 2, and are opposed to one another in the pairs A, B and C, D. An electric motor (not shown) mounted on the underside of the platform 1 drives the pulleys 3 of the pair A, B at a first speed and also drives, through a speed reduction transmission (not shown), the pulleys 3 of the pair C, D at a second, slower speed. In operation a corrugated strip is advanced along the surface of the raised portion 2 of the platform 1 by and between the pairs of belt drives A, B and C, D. The opposed surfaces of the belts 5 frictionally engage the corrugated opposite edges of the strip. Since the belts 5 of the pair A, B are driven faster than those of the pair C, D the corrugations become bunched together as the strip advances between the two pairs A, B and C, D. As the strip emerges from between the belts 5 of the second pair C, D, the corrugations spring open to assume a reduced pitch angle compared to that present prior to lengthwise compression in the apparatus. In a modified construction of the preferred apparatus, the belt drives A and C are spring biased towards the belt drives B and D, respectively. More particularly, the slots 9 in the sliding blocks 7 of the belt drive assemblies A and C are replaced by studs which project downwardly through guide slots in the platform 1. The studs are engaged by tension springs anchored to the platform 1, which springs bias the blocks 7 of the drive assemblies A and C towards the assemblies B and D, respectively, for gripping the corrugated strip between the belts 5. WHAT WE CLAIM IS:-

1. A method of continuously producing corrugated strip from metal strip stock, comprising the steps of initially forming transverse corrugations in the strip and subsequently subjecting the corrugated strip to lengthwise compression between two pairs of friction belts moving at differential speed, characterised in that the friction faces of the belts are applied to the ends of the corrugations at opposite edges of the strip.

2. Apparatus for use in carrying out the method according to Claim 1, comprising: (a) a support surface adapted to support the strip on the peaks of the cor rugations at one side thereof; (b) first and second pairs of friction belts arranged successively along the sup port surface, the friction faces of each pair of belts being opposed to one another across and in a perpen dicular relation to the support surface for engaging the opposite edges of the strip; and (c) means for driving the first and second pairs of friction belts at a differential speed, such that the first pair moves faster than the second pair.

3. Apparatus according to Claim 2, in which at least one friction belt of each pair is supported for displacement, and is spring biased, towards the other belt of the same pair.

4. Apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.