DIAGONAL CUTTER FOR CUTTING-OFF A METAL-SHEET BAND INTENDED FOR A SPIRAL-SEAMED PIPE

Abstract: Diagonal cutter for cutting-off of a metal-sheet band intended for a spiral-seamed pipe, the said cutter comprising a frame and two disc-shaped shear blades (13, 23) supported on separate, parallel shafts of rotation (10, 20), the circumferential edges of the said blades forming a shearing gap between them, as well as actuating members (32 to 34) for displacing the shear blades transversely to the path (A) of movement of the metal-sheet band (2) to be cut. Each of the shafts of rotation is provided with a chopping blade (12, 22), which is placed, in a way in itself known, opposite the shearing blade placed on the other shaft of rotation so that the shearing blade forms a counterpiece for the chopping blade. Each chopping blade can be rotated in relation to the shearing blade placed on the same shaft of rotation. The chopping blades are connected to actuating members in view of rotating the chopping edges (26) of the chopping blades (12, 22) against the shearing blades (13, 23) at different longitudinal edges of the metal-sheet band for the purpose of cutting-off the sharp tip pieces (37A) out of the sheet band, which tip pieces are produced on the diagonal shearing (36).

Description: Diagonal cutter for cutting-off a metal-sheet band intended for a spiral-seamed pipe The present invention is concerned with a diagonal cutter for cutting-off a metal-sheet band intended for a spiral-seamed pipe, the said cutter comprising a frame and two disc-shaped shear blades supported on separate, parallel shafts of rotation, the circumferential edges of the said blades forming a shearing gap between them, as well as actuating members for displacing the shear blades transversely to the path of movement of the metal-sheet band to be cut. Spiral-seamed pipes have been manufactured in the factory by turning a metal-sheet band in the spiral shape into a seamed continuous pipe, out of which pipe portions of desired length have been cut off by cutting off the pipe at desired positions by means of a cut-off disc. Such a mode of cutting off, however, causes an abundance of disturbing noise. , From the Swedish Patent 407,524, a diagonal cutter is known by means of which the metal-sheet band can be cut off to such a length that a spiral-seamed pipe of desired diameter and length can be turned out of the sheet band in this way cut off. It is an advan- tage of such a mode of manufacture that the cutting off of the metal-sheet band can be performed in advance as a relatively noise-free working step by means of the suggested diagonal cutter. Since the metal-sheet band cut off is turned to a pipe with a certain pitch, the shear line must pass diagonally from one longitudinal edge of the sheet band to the other, whereat the magnitude of the shear angle is 1 to 40°, depending- on the diameter of the pipe and on the pitch of the spiral. Owing to the seaming of the spiral-seamed pipe, a projecting thorn is formed at both ends of the complete pipe, because of which it is necessary to cut off a triangular tip piece out of both ends of the diagonally cut metal-sheet band. The diagonal cutter in accordance with the said Swedish patent is provided with two disc-shaped shear blades, which are mounted on shafts of rotation perpendicular to each other. Such a construction makes the initial cutting of the shear blades into the sheet band difficult, and in order that it should be possible to make the shearing start exactly at the correct point, a notch or a similar starting point must be prepared at the longitudinal edge of the metal-sheet band. For this purpose, a separate punching device is required in the Swedish diagonal cutter. True enough, this punching device can be utilized for cutting-off of the said triangular tip piece of the sheet band, but when the angle of the shearing line is very small, the side of the tip piece becomes so long that it cannot be cut off by means of the punching device. In such a case, by means of the Swedish diagonal cutter, the metal-sheet band has been cut off at a slightly larger angle, so Ithat the thorn formed at the end of the pipe remains inside the complete seam. In such a case, however, the end of the completed pipe remains correspondingly slightly diagonal. From the U.S. Patents 3,110,208 and 3,415,148, cutters are previously known for evening of the longi¬ tudinal edge of a metal-sheet band. The cutters comprise two disc-shaped shear blades supported on separate parallel shafts of rotation. On one of the shafts of rotation, a disc-shaped chopping blade is mounted as connected non-rotably to the shear blade, so that the other shear blade functions as a counterpart for the chopping blade. The chopping blade, which is provided with several projecting chopping edges, revolves con¬ stantly along with the shear blade, so that the strip cut-off from the longitudinal edge of the sheet band becomes chopped into little pieces as the cutting of the sheet band makes progress. By means of such a cutter, IjϋR β ΛT / O PI ~ — it is not- possible to perform diagonal shearing of a sheet band, because the chopping edges would cut suc¬ cessive notches into the diagonal cutting edge of the metal-sheet band. The object of the present invention is to provide a diagonal cutter which avoids the above draw¬ backs and permits cutting-off of the tip pieces of the metal-sheet band from both ends of the pipe in connection with the diagonal shearing of the sheet band by making use of existing shear blades with relatively little accessories. This objective is achieved by means of a diagonal cutter in accordance with the present inven¬ tion, which is characterized in - that each of the shafts of rotation is pro- vided with a chopping blade, which is placed, in a way in itself known, opposite the shearing blade placed on the other shaft of rotation so that the shearing blade forms a counterpiecε for the chopping blade, - that each chopping blade can be rotated in relation to the shearing blade placed on,the same shaft of rotation, and - that the chopping blades are connected to actuating members in view of rotating the chopping edges against the shearing blades at different longitudinal edges of the metal-sheet band. The invention is based on the idea that, by providing each shearing blade with a chopping blade of its own, whereat the shearing blades act as counter- pieces for the said chopping blades, it is possible to direct the chopping effect at the sheet band at opposite sides of the shear line produced by the shearing blades. When the chopping blades are installed rotable relative the shearing blades, it is possible to make, the chopping blades operate at the desired stages of the diagonal shearing. Owing to this, the sharp tip piece remaining at the rear part of the band portion to be cut-off from the metal-sheet band can be chopped off from the band -ξVREA OMPI at the final end of the diagonal shear line, and the sharp tip piece remaining at the front edge of the cut-off sheet band can be chopped off at the initial end of the diagonal shear line. The said tip pieces of the sheet band can be cut off irrespective of the length of the side of the tip piece. The chopping takes place automatically during the shearing of the sheet band. Under these circumstances, a tip piece of correct shape can be chopped off the sheet band even in the case of small angles of the shear line. When the shear blades are installed so as to be cut into the sheet band in a way in itself known perpendicularly from opposite sides of the band, the shear blades do not tend to turn the initial end of the sheet band to the side, but they rise precisely onto the sheet band. This is why no separate initial and final band-notching means and no corresponding separate working steps are required. The invention will be described in more detail in the following with reference to the attached drawings, wherein Figures 1 and 2 are schematical views of a spiral-seaming machine provided with a diagonal cutter in accordance with the invention, Figure 3 is an enlarged vertical view of the construction of a preferred embodiment of the diagonal cutter, Figure 4 is a perspective view of the principle of operation of the diagonal cutter, Figures 5 and 6 are top views of two different modes of cutting of a metal-sheet band. The spiral-seaming machine shown in Figures 1 and 2 of the drawings comprises a- starting frame 1 for the sheet-band roll 2 to be processed, a diagonal cutter 3 for cutting the sheet band into pieces of desired length, folding rolls 4 for preliminary shaping of the longitudinal edges of the sheet band to the shape required by the seaming, and seaming rolls 5 for bending the sheet band into a spiral-shaped pipe and for performing the seaming.' The result is a spiral- seamed metal-sheet pipe 6. The diagonal cutter comprises a support 7, on which two blade groups 8 and 9 are installed. The shaft of rotation 10 belonging to the upper blade group is journalled on the support by means of bearings 11. A disc-shaped chopping blade 12 is rigidly mounted on the shaft of rotation. At the side of the said chopping blade, . a disc-shaped diagonal-shearing blade 13 is placed coaxially, the said blade 13 being journalled to the support by means of bearings 14 and being mounted freely rotatingly to the end of the shaft of rotation, as is indicated by means of broken lines. The shaft of rotation is connected to a rotation motor 15. The lower blade group 9 is mounted on the base 16, which is mounted pivotably on the support 7 by means of a pivot shaft 17. ' The shaft of rotation 20 belonging to the lower blade group is mounted to the base by means of a bearing 18, and a disc-shaped chopping blade 22 is attached rigidly to the end of the shaft of rotation. At the side of the said blade 22, there is a disc¬ shaped diagonal-shearing blade 23, which is rigidly attached to a sleeve 19 freely revolving on the shaft of rotation, the said sleeve 19 being supported on the support by means of bearings 21. The shaft of rotation 20 is connected to a rotation motor 15 of its own. The shafts of rotation 10 and 20 are posi¬ tioned substantially parallel to each other, and between them there is a slot 24 in the support. The diagonal-shearing blades of the two blade groups are placed as axially displaced relative each other so that their circumferential edges facing each other are located so that they overlap each other and form a shearing gap 25 between them. The chopping blade of the upper blade group is placed straight above the diagonal-shearing blade of the lower blade group and, correspondingly, the chopping blade of the lower blade group is placed straight underneath the diagonal-shearing blade of the upper blade group. Each chopping blade is provided with a chopping edge 26 placed on the circum¬ ference. In the frame, underneath the base of the lower blade group, a positioning device 27 is placed, which comprises an actuating cylinder 28, which is mounted on the support and to whose piston rod a wedge-shaped slide 29 is attached, which is placed against a station¬ ary counterpiece 30 provided on the support, on one hand, and against a counterpiece 31 with diagonal face provided on the base 16, on the other hand. The arrangement is such that the slide can be pressed by means of the actuating cylinder more or less between the counter- pieces 30 and 31 , whereat the lower blade group moves substantially vertically relative the upper blade group. The support 7 is placed in support on a sledge 33 placed underneath, by means of a vertical pivot shaft 32, which sledge 33 is supported by horizontal guides 34, which are installed glidingly on a stationary support 35 carried by the frame of the diagonal cutter. The sledge is connected to an actuating device 39, illustrated only schematically, for the purpose of displacing the sledge relative the support 35. The sledge is, moreover, provided with a locking device, not shown, by means of which the angular position of the support 7 relative the direction of movement of the sledge can be locked. The diagonal cutter is installed in the path A of movement of the metal-sheet band 2 to be cut so that the guides 34 are placed perpendicularly to the path of movement of the sheet band, as is shown in Fig. 4, and that the path of movement of the sheet band passes 'BU EA OMPϊ through the slot 24 in the support 7. Both of the blade groups are, thus, placed at opposite sides of the sheet band. By means of the positioning device 27, it is possible to adjust the shearing gap between the two blade groups, i.e. the degree of overlapping of the diagonal- shearing blades, so that it corresponds to the thickness . of the metal-sheet band to be cut. The angle B of the shear line of the sheet band, Fig. 5, relative the longitudinal edge of the band depends on the diameter of the spiral-seamed pipe to be manufactured and on the pitch of the spiral. The support 7 is locked onto the sledge at such an angular position that the shafts of rotation of the blade groups are placed in a plane perpendicular to the shear line. When the sheet band is being pulled through the slot in the support and when the sledge is being displaced in the transverse direction of the sheet band at a uniform speed adapted to the inclination of the shear line and to the speed of movement of the band, the diagonal-shearing 'blades are first cut into the sheet band at the initial end of the shear line, and thereupon they roll along opposite faces of the band and cut through the sheet band along the shear line. In order that detrimental projecting thorns should not be formed at the ends of the complete spiral- seamed pipe, out of the sheet band, from the initial end and final end of the shear line, from different sides of the shear line, ' triangular tip pieces 37A and 37B must be chopped off, as is shown in Fig. 5. In order to achieve this, the upper chopping blade 12 is rotated by means of the motor at such a moment that the chopping edge 26 of the chopping blade is cut into the sheet band at the desired distance from the initial end of the shear line. Thereat, the circumferential face of the lower diagonal-shearing blade 23 acts as the counterpiece for the cutting blade. The chopping blade is rotated by means of a motor in order that the slight bond that remains on chopping by compression could be torn apart and the tip piece 37A be cut off. After the final end of the shear line of the sheet band has moved close enough to the blade groups, the chopping blade 22 of the lower blade group is rotated in a corresponding way so that the other tip piece 37B is cut off. If it is desirable to keep the sheet bands attached to each other while the bands pass through the spiral-seaming machine, uncut bonds 38 are allowed to remain on the shear line at regular distances. The bonds are produced by providing the outer circumference of one of the diagonal-shearing blades, acting as the shearing edge, with corresponding notches. In order that bonds should not remain on the shear line at the tip pieces to be cut apart, a higher overlapping depth of the blades is used when running at the starting and finishing portions of the shear line. The drawings and the related description are just supposed to illustrate the idea of the invention. In its details, the diagonal cutter in accordance with the invention may show variation within the scope of the patent claims.

Claims: WHAT IS CLAIMED IS: 1. Diagonal cutter for cutting-off of a metal-sheet band (2) intended for a spiral-seamed pipe, the said cutter comprising a frame (7) and two disc¬ shaped shear blades (13, 23) supported on separate, parallel shafts ' of rotation (10, 20) , the circumferen¬ tial edges of the said blades forming a shearing gap (25) between them, as well as actuating members (39) for displacing the shear blades transversely to the path (A) of movement of the metal-sheet band (2) to be cut, c h a r a c t e r i z e d in - that each of the shafts of rotation (10, 20) is provided with a chopping blade (12, 22) , which is placed, in a way in itself known, opposite the shearing blade (13, 23) placed on the other shaft of rotation so that the shearing ' blade forms a counterpiece for the chopping blade, - that each chopping blade (12, 22) can be rotated in relation to the shearing ' blade ( * J3, 23) placed on the same shaft of rotation (10, 20), and - that the chopping blades are connected to actuating members (15) in view of rotating the chopping edges (26) of the chopping blades against the shearing blades (12, 23) at different longitudinal edges of the metal-sheet band. 2. Diagonal cutter as claimed in claim 1, c h a r a c t e r i z e d in that each shearing blade (13, 23) is installed as freely revolving and each chopping blade (12, 22) as non-revolving on the corres¬ ponding shaft of rotation (10, 20). 3. Diagonal cutter as claimed in claim 2, c h a r a c t e r i z e d in that each shaft of ro¬ tation (10, 20) is rotated by an actuating member (15) . 4. Diagonal cutter as claimed in claim 2 or 3, c h a r a c t e r i z e d in that each chopping blade (12, 22) consits of a disc on whose circumference there is a projecting chopping edge (26) . OMPI

Inventors: PULKKINEN PEKKA, SANDHOLM PENTTI, PULKKINEN, PEKKA, SANDHOLM, PENTTI
Applicants: NOKIA OY AB, OY NOKIA AB
Application year: 1983
Main classification: B21C37
IPC codes: B21C37, B23D19