Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
  • B21C37/06—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of tubes or metal hoses; Combined procedures for making tubes, e.g. for making multi-wall tubes
  • B21C37/12—Making tubes or metal hoses with helically arranged seams
  • B21C37/127—Tube treating or manipulating combined with or specially adapted for use in connection with tube making machines, e.g. drawing-off devices, cutting-off
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23D—PLANING; SLOTTING; SHEARING; BROACHING; SAWING; FILING; SCRAPING; LIKE OPERATIONS FOR WORKING METAL BY REMOVING MATERIAL, NOT OTHERWISE PROVIDED FOR
  • B23D21/00—Machines or devices for shearing or cutting tubes
  • B23D21/14—Machines or devices for shearing or cutting tubes cutting inside the tube
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B26—HAND CUTTING TOOLS; CUTTING; SEVERING
  • B26D—CUTTING; DETAILS COMMON TO MACHINES FOR PERFORATING, PUNCHING, CUTTING-OUT, STAMPING-OUT OR SEVERING
  • B26D3/00—Cutting work characterised by the nature of the cut made; Apparatus therefor
  • B26D3/16—Cutting rods or tubes transversely
  • B26D3/163—Cutting tubes from the inside

Definitions

• the present invention relates to an assembly for cutting a rotatable tube, in particular a helically-wound lock-seam tube to be used in ventilation ductworks.
• Such tube cutting assemblies are often included in machines for producing helically-wound lock-seam tubes.
• a metal strip is helically wound into a tube in a forming head and locked in a helical lock seam.
• Basic examples of such machines or tube formers are shown in GB-A-2,213,748 (Fig. 1) and US-A-4 , 706 , 481 (Fig. 15) .
• the tube cutting assembly is mounted after the forming head.
• Known tube cutting assemblies of this type normally comprise a pair of opposite rotatable cutting wheels which are brought into engagement with the tube wall and co-operate to cut or sever the rotating tube.
• a first cutting wheel is disposed inside the tube and a second cutting wheel is disposed outside the tube.
• the outer cutting wheel is brought into engagement with the outer surface of the tube and its cutting edge cuts through the tube wall against the cutting edge of the inner cutting wheel.
• Fig. 1 shows a cut tube seen from the end.
• Fig. 1 shows a cut tube seen from the end.
• Such undesirable deformations of the tube wall a-t the end sometimes occur on thin- walled tubes when the two cutting wheels are brought into engagement with the tube wall at high speed.
• the same difficulties may arise when the rotational speeds of the tube and the cutting wheels are not synchronised.
• the problem is particularly common when cutting helically- wound lock- seam tubes, since the helical lock seam causes "bumps" at the cutting location between the cutting wheels which in turn may lead to deformations of the end of the cut tube .
• the deformations at the end of the cut tube make it hard to connect various tubular components to the tube which are inserted in the tube from the end.
• fittings like bends, T pieces, reducers and other coupling members are connected to the ventilation ducts. If these fittings do not fit the ducts, the fitter either has to eliminate the end deformations manually or, if it comes to the worst, discard the duct as scrap.
• Summary of the Invention The object of the invention is to provide a new tube cutting assembly which is improved over prior art and by means of which the problems above are eliminated or at least reduced.
• both cutting wheels have a peripheral elastic member for engagement with the tube wall at the cutting location. This embodiment provides for a symmetric cutting operation with a damping effect on both sides of the tube wall . The deforming forces are reduced on both sides.
• the peripheral elastic members are offset radially inside the cutting edge of the associated cutting wheel.
• the peripheral surface of each elastic member is supported by an opposite tube supporting surface of the opposite cutting wheel. This leads to a very smooth cutting operation that reduces the risk of deformations at the end of the cut tube.
• each peripheral elastic member comprises an annular element which is fastened to the front surface of the associated cutting wheel.
• This design of the elastic members is advantageous since it is simple and provides a good damping effect .
• the annular elastic ele- ment is clamped against the front surface of the associated cutting wheel by means of a clamping disc which is fastened to said front surface.
• a clamping disc which is fastened to said front surface.
• the clamping disc is fastened to said front surface by means of a central tightening screw which is coaxial with the rotational axis of the associated cutting wheel. This fastening of the annular elastic element is very secure and easy to handle.
• the peripheral elastic member is mounted in a peripheral recess of the associated cutting wheel.
• a well-balanced damping effect is accomplished during the cutting opera- tion.
• Peripheral surfaces of the cutting wheel on either side of the peripheral elastic member can support the tube wall at the cutting location, which makes cutting smooth .
• the peripheral elastic member is an annular element with a peripheral surface which is disposed radially outside the cutting edge of the associated cutting wheel. This design provides for an initial damping of the cutting impact, which reduces the risk of deformations at the end of the cut tube.
• the annular elastic element of this embodi- ment is clamped in the peripheral recess by means of a clamping disc.
• peripheral elastic member be made of a polymer material .
• Fig. 1 is an end view of a tube cut with a prior-art tube cutter, the tube wall having undesirable deformations .
• Fig. 2 is a sectional view of a tube cutting assembly according to a first aspect of the invention.
• Fig. 3 is a sectional view of a tube cutting assem- bly according to a second aspect of the invention.
• Fig. 1 shows a prior-art tube 1 of circular cross- section having undesirable deformations 2 at the cut end.
• the deformations 2 are shown as indentations inwards, but the prior-art cutting operation can also cause other types of deformations, such as small cuts or burrs.
• Fig. 2 shows a tube cutting assembly according to a first aspect of the invention.
• the tube 3 has a helical lock seam 4 which is shown schematically.
• the lock seam 4 projects outwards from the tube wall 5 which for instance has a wall thickness of 0.4-0.5 mm.
• the tube 3 is rotated about a centre axis C and moved in the direction of arrow A from a forming head (not shown) .
• the tube cutting assembly comprises a first cutting wheel 6 which is located inside the tube 3 and which is rotatable about an axis of rotation Rl parallel with the centre axis C of the tube 3.
• the inner cutting wheel 6 is circular and has a peripheral cutting edge 7 and a peripheral tube supporting surface 8 to be engaged with the tube wall 5.
• a peripheral elastic member here in the shape of an annular element or ring 10, preferably of polymer material.
• the elastic ring 10 is mounted by means of a circular clamping disc 11 which is fastened to the front surface 9 of the wheel 6 by means of a central tightening screw 12 which is coaxial with the rotational axis Rl of the wheel 6.
• the tube cutting assembly further comprises an opposite second cutting wheel 18 which is located outside the tube 3 and which is rotatable about an axis of rotation
• the outer cutting wheel 18 is circular and of the same design as the inner cutting wheel 6.
• the outer wheel 18 has a peripheral cutting edge 19, a peripheral tube sup- porting surface 20 and a front surface 21.
• An elastic ring 22, preferably of polymer material, is mounted on the front surface 21 by means of a circular clamping disc 23 fastened by a tightening screw 24 which is coaxial with the rotational axis R 2 of the outer wheel 18.
• the components providing for the rotation of the outer wheel 18 are the same as for the inner wheel 6 and need not to be described in detail .
• the outer cutting wheel 18 is movable in a direction perpendicular to the centre axis C of the tube 3 for bringing the opposite cutting wheels 6 and 18 into cutting engagement at a cutting location L between the wheels 6, 18.
• Means 25 which provide this movement (arrow B) are of known type and are only shown schematically.
• the tube 3 is rotated and moved in the direction of arrow A.
• the lower or outer cutting wheel 18, which is rotating is raised and brought into engagement with the outer surface of the tube wall 5.
• the cutting edge 19 of the outer wheel 18 cuts through the tube wall 5 and, in doing this, the tube supporting surface 20 of the outer wheel 18 abuts the outer surface of the tube wall 5.
• the inner cutting wheel 6 (which is rotating but stationary with respect to the cutting direction B) supports and backs up the outer wheel 18.
• the cutting edge 7 of the inner cutting wheel 6 cuts through the tube wall 5 from the inside and the tube supporting surface 8 abuts the inner surface of the tube wall 5.
• the respective cutting edges 7 and 19 as well as the respective tube supporting surfaces 8 and 20 abut the respective elastic rings 10 and 22 which are compressed. Owing to the compression of the elastic rings 10 and 22, the cutting of the tube 3 is very smooth and no "bumps" occur.
• the elastic rings 10 and 22 take up the transverse cutting forces and provide for a secure cutting of the tube 3 which is not deformed at the cut end.
• the tube wall 5 is pressed between the peripheral surface 10a of the elastic ring 10 of the inner wheel 6 and the peripheral tube supporting surface 20 of the outer wheel 18.
• the tube wall 5 is pressed between the peripheral surface 22a of the elastic ring 22 of the outer wheel 18 and the peripheral tube supporting surface 8 of the inner wheel 6.
• the elastic rings 10 and 22 are both offset radially inside the cutting edges 7 and 19 of the associated wheels 6 and 18.
• the peripheral surfaces 10a and 22a are disposed at a distance inwardly from the cutting edges 7 and 19.
• the cutting edges 7 and 19 can initiate the cutting through of the tube wall 5 before the elastic rings 10 and 22 are compressed in order to avoid undesirable deformations of the cut end of the tube 3.
• Fig. 3 shows a tube assembly according to a second aspect of the invention. The basic idea behind this structure is the same as described above, but the design of the cutting wheels is somewhat different.
• the outer cutting wheel 30 has a peripheral elastic member, here in the shape of an annular ring 31, preferably of polymer material, mounted in a peripheral recess 32 of the wheel 30.
• the elastic ring 31 is fastened in the recess 32 by means of a clamping disc 33 tightened by a screw 34 which is coaxial with the axis of rotation R2 of the outer wheel 30.
• the peripheral surface 31a of the elastic ring 31 is disposed radially outside the peripheral cutting edge 35 of the outer wheel 30, which means that the elastic ring 31 is first brought into engagement with the tube wall 5 in the cutting operation. Thus, the compression of the elastic ring 31 starts.
• the inner cutting wheel 36 has no elastic member, but two peripheral cutting edges 37 and 38, between which there is a peripheral tube supporting surface 39.
• the outer wheel 30 is raised by means 25 (arrow B) and brought into engagement with the tube wall 5 at the cutting location L.
• the cutting edges 35, 37 and 38 co-operate to cut the tube 3, the elastic ring 31 being compressed by the tube supporting surface 39.
• the peripheral edge 40 of the clamp- ing disc 33 close to the elastic ring 31 acts as a cutting edge during this compression.
• the tube 3 is cut at two points, leaving a "ring" of the tube 3 as scrap.
• peripheral surfaces 30a and 33a of the outer cutting wheel 30 and the clamping disc 33 serve as tube supporting or back-up surfaces for the tube wall 5, which enhances the cutting operation.
• An advantage of the tube cutting assembly according to the invention is that it can either be supplied as an attachment to an existing tube former or be mounted on a new tube former.
• Either one of or both of the opposite cutting wheels may be provided with a peripheral elastic member to be compressed during the cutting operation.
• either one of or both of the cutting wheels can be movable in a direction transversely of the centre axis of the tube, although it is preferred for the outer wheel to be movable .

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Forests & Forestry (AREA)
• Turning (AREA)
• Sawing (AREA)
• Knives (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=20289320

Family Applications (1)

Country Status (8)

Families Citing this family (8)

Family Cites Families (5)

• 2002
  • 2002-10-18 SE SE0203103A patent/SE526005C2/sv not_active IP Right Cessation
• 2003
  • 2003-10-16 AU AU2003276114A patent/AU2003276114A1/en not_active Abandoned
  • 2003-10-16 CA CA002502564A patent/CA2502564A1/en not_active Abandoned
  • 2003-10-16 EP EP03808729A patent/EP1565280A2/de not_active Withdrawn
  • 2003-10-16 RU RU2005114497/02A patent/RU2005114497A/ru not_active Application Discontinuation
  • 2003-10-16 CN CNA2003801015729A patent/CN1705526A/zh active Pending
  • 2003-10-16 WO PCT/EP2003/011461 patent/WO2004035239A2/en not_active Application Discontinuation
  • 2003-10-16 JP JP2004544254A patent/JP2006502872A/ja not_active Withdrawn

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events