Metal tools and implements – making – Saw-making or furbishing device or machine
Patent
1998-02-25
2000-05-30
Watts, Douglas D.
Metal tools and implements, making
Saw-making or furbishing device or machine
76 26, 76 27, B23D 6318
Patent
active
060678798
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a procedure as defined in the preamble of claim 1 for straightening a circular-saw blade into a desired shape. The invention also relates to an apparatus as defined in the preamble of claim 6 for straightening a circular-saw blade into a desired shape.
Circular-saw blades lose their original shape during use. The tensions in the blade change during use as a result of mechanical lateral forces and the thermal effects produced by such forces. Depressions are formed in the blade and the blade may get twisted, leading to a deteriorated sawing result. So far, the straightening of circular-saw blades has usually been performed manually by hammering, which means that the quality of work has been dependent on the craftsmanship of the person carrying out the operation. Manual straightening takes time and a successful result is not guaranteed. Moreover, different circular-saw blades having different damages require different treatment. An advantageous circular-saw blade design is one with a slightly `cup-like` shape, i.e. with a slightly curved cross-sectional form. When the blade is rotated at nominal speed, its cuplike shape is straightened. The cup-like shape varies depending on things like the size and material of the blade and the rotational speed it is designed for. Also, manual straightening and repair of blades whose thickness is reduced radially from the centre towards the edges of the blade has been very difficult, even impossible.
Some devices for straightening a circular-saw blade are also known. From EP application 0521824 A1, a machine for straightening a circular-saw blade is known in which the straightening is effected by means of rollers placed on opposite sides of the blade and controlled on the basis of a measurement performed by means of a dial indicator. Again, U.S. Pat. No. 3,964,348 presents a procedure and machine for the tensioning and straightening of a circular-saw blade, in which dents are straightened by hammering with a hammering device. The blade is hammered from one side only. Among the drawbacks of the solutions known in the art is the inaccuracy of the measurement used for controlling the straightening treatment. In the known solutions, the straightening treatment is performed in a random order, and this has led to unsatisfactory straightening results. Furthermore, treating the blade with rollers and hammers creates unnecessary tensions or expansion of the blade, and these have a deteriorating effect on the final result of the treatment.
The object of the present invention is to achieve a completely new type of procedure and apparatus for straightening circular-saw blades into a desired shape, avoiding the drawbacks of the solutions previously known in the art.
The invention is characterized by what is presented in the claims.
The solution of the invention has several significant advantages. The procedure of the invention can be used to automatically straighten circular-saw blades without the need for special skill. The procedure is fast and accurate. It makes it possible to achieve a straightened and tensioned circular-saw blade having a maximal rigidity, which also remains very accurately in alignment while rotating. Blades repaired by applying the procedure and apparatus of the intention are tested in conditions corresponding to an actual operating situation, ensuring that they will also work properly in their real place of use. The measurement of blade geometry forming the basis of the treatment is very accurate. The tools used in the treatment produce a very accurate effect on the blade.
This means that unnecessary tensions and expansion of the blade are avoided. The blade is mounted in a manner corresponding to its mounting on a real sawing machine. The behaviour of the blade can be observed while it is rotating at a correct speed. The procedure and apparatus of the invention make it possible to produce a report giving blade-specific information about the faults detected and corrected as well as about the repair operations performed. Moreover,
REFERENCES:
patent: 3964348 (1976-06-01), Dawson
patent: 4085630 (1978-04-01), Williams
patent: 4138908 (1979-02-01), Kampmann et al.
patent: 5269205 (1993-12-01), Oppliger
patent: 5522283 (1996-06-01), Brown
Rautio Kai
Rautio Kauko
Veisto-Rakenne Rautio Oy
Watts Douglas D.
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