Method for Sawing a Long Profile and Machine for Cutting Same to Length

Abstract

The invention relates to a method for sawing a long profile (3) in that a sawing disc (2) having teeth (6) arranged around a circular outer circumference of the sawing disc (2) is rotated freely, the sawing disc (2) is advanced from a freely rotating position to an outer wall of the long profile (3), and a zero tooth (Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4) engages as the first of the teeth (6) in the material of the outer wall, wherein, during the free rotation of the sawing disc (2), lateral runouts (d) of the teeth (6) are determined, and a tooth (6) having a minimum lateral runout (d) is determined and used as the zero tooth (Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4).

Claims

1. Method for sawing a long profile (3) in that a sawing disc (2) having teeth (6) arranged around a circular outer circumference of the sawing disc (2) is rotated freely, the sawing disc (2) is advanced from a freely rotating position to an outer wall of the long profile (3), and a zero tooth (Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4) engages as the first of the teeth (6) in the material of the outer wall, characterised in that during the free rotation of the sawing disc (2), lateral runouts (d) of the teeth (6) are determined, and a tooth (6) having a minimum lateral runout (d) is determined and used as the zero tooth (Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4).

2. Method according to claim 1, characterised in that lateral runouts (d) of the teeth (6) are continuously measured during the rotation relative to a distance sensor (4) in a fixed position and angular positions (α) of the saw disc (2) are continuously measured, a lateral runout angular position profile of the sawing disc (2) is determined and a tooth (6) with minimal lateral runout (d) is determined from the profile.

3. Method according to claim 1, characterised in that an advance and the rotation of the sawing disc (2) are controlled in such a way that the tooth (6) with minimal lateral runout (d) becomes the zero tooth (Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4).

4. Method according to claim 1, characterised in that a zero position of the sawing disc (2) is determined.

5. Method according to claim 1, characterised in that after the sawing, a tooth (6) with minimal lateral runout (d) is determined and is used as the zero tooth (Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4) before each subsequent sawing of a further long profile.

6. Method according to claim 1, characterised in that a subsequent zero tooth (Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4) spaced furthest apart from the zero tooth (Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4) of the sawing operation is determined for subsequent sawing.

7. Machine for cutting sections of a long profile (3) to length with a receptacle (1) for the long profile (3) of a sawing disc (2) with teeth (6) arranged around a circular outer circumference of the sawing disc (2) and an advancing direction (V) for the sawing disc (2) in the direction of the receptacle (1), characterised in that, laterally along an axis of rotation alongside the teeth (6) of the sawing disc (2) there is arranged a distance sensor (4), which is directed towards the teeth (6) of the sawing disc (2) and measures lateral runouts (d) of the teeth (6) during the free rotation of the sawing disc (2), and an evaluation unit which is connected to the distance sensor (4) by which measured values from the distance sensor (4) can be supplied to the evaluation unit.

8. Machine according to claim 7, characterised by an angle measuring device for a rotational position of the sawing disc (2) which is connected to the evaluation unit and by which a lateral runout angular position profile of the sawing disc (2) can be determined and by which a zero tooth (Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4) can be determined.

9. Machine according to claim 7, characterised by a control for the rotation and the advancing of the sawing disc (2) which makes it possible to select the zero tooth (Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4) as first tooth (6) which engages in the material of the outer wall of the long profile (3).

10. Machine according to claim 7, characterised in that the control makes it possible for a subsequent zero tooth (Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4) spaced furthest apart from the zero tooth (Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4) of the sawing to be determined for subsequent sawing.

Description

[0026] The invention is described with reference to an embodiment with three drawings. In the drawings:

[0027] FIG. 1 shows a schematic side view of a sawing disc placed in a receptacle in three different rotational positions with lateral runout,

[0028] FIG. 2 shows a lateral runout angular position profile of the sawing disc in FIG. 1,

[0029] FIG. 3 shows a metal tube with different saw grooves.

[0030] FIG. 1 shows a side view of a receptacle 1 with a sawing disc 2 which is circular around the circumference. The sawing disc 2 is part of a tube cutting machine which is not described in FIG. 1. In FIG. 1 the sawing disc 2 is positioned remote from the ground above a metal tube 3. The sawing disc 2 is a component of a tube cutting machine which is not described in FIG. 1. The sawing disc 2 is NC controlled. An angular position of the receptacle 1, and thus of the sawing disc 2 clamped non-rotatably relative thereto in the receptacle 1, can be determined by the NC control. Furthermore, the NC control enables the sawing disc 2 to advance by advancing the receptacle 1 in the direction of the metal tube 3 to be cut to length. In this case a direction of advance V is perpendicular to a longitudinal direction L of the metal tube 3 to be cut to length. During the advance, the sawing disc 2 initially rotates freely and without contact with the metal tube 3 and is advanced until the actual cutting operation of the sawing method begins, in which teeth 6 of the sawing disc 2 come into contact with the metal tube 3.

[0031] The sawing disc 2 illustrated in FIG. 1 has, like almost all commercially available sawing discs 2, a so-called lateral runout d. The lateral runout d is understood to be a deviation from the ideal flat shape of the sawing disc 2. Even if the sawing disc 2 is correctly gripped in the receptacle 1, it is not oriented exactly perpendicular to the outer wall of the metal tube 3 in every angular position, but, depending upon the angular position α of the sawing disc 2, the tooth 6 coming closest to the outer wall has a lateral runout d, i.e. a deviation from the zero position. The zero position is determined by a perpendicular line which is fixed by the position of the ideal flat sawing disc 2 in the receptacle 1. The zero position of the sawing disc 2 without lateral runout is represented in FIG. 1 by a sawing disc 2 shown by broken lines.

[0032] Furthermore, in FIG. 1 two angular positions a of the same sawing disc 2 are represented by sawing discs 2 shown by solid lines. The sawing disc 2 shown by solid lines is characterised by the lateral runout d. In addition to the sawing disc 2, a distance sensor 4 is provided which is advanced in the direction of the axis of rotation of the sawing disc 2. This is an inductive distance sensor 4 which precisely determines the distance of the teeth 6 from the distance sensor 4 in the 0.1 micrometre range. The distance sensor 4 makes it possible to record a measured value every 1.0 milliseconds so that, with 300 rotations per minute, approximately 200 measurement points per rotation of the sawing disc 2 can be taken. The distance sensor 4 is calibrated so that it measures a distance from the ideal zero position of the tooth 6 of the sawing disc 2. Depending upon the control, shorter cycles are also possible.

[0033] FIG. 2 shows a basic curve of the lateral runout d as a function of the angular position a of the sawing disc 2 in a full rotation of the sawing disc 2. The profile illustrated in FIG. 2 is produced by interpolation of the recorded measured values. FIG. 2 shows in particular that at four different angular positions α.sub.1, α.sub.2, α.sub.3, α.sub.4 no lateral runout d is present, i.e. the teeth 6 which, in these angular positions α.sub.1, α.sub.2, α.sub.3, α.sub.4, sweep past the distance sensor 4 have no lateral runout d. The teeth 6 with minimal or absolutely no lateral runout d are designated here as zero teeth Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4. An evaluation device (not shown) makes it possible to control the sawing disc 2 so that during the cutting operation one of the zero teeth Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4 is the first tooth 6 to strike the outer surface of the metal tube 3 and removes some material from the outer surface of the metal tube 3. The advance per tooth 6 in the advancing direction V is approximately 0.05 mm to 0.35 mm. Because the first tooth 6 predetermines the direction of a saw groove 7 in the metal tube 3, it is crucial that this tooth 6 has no lateral runout d, in order to introduce a cut exactly at right angles into the outer wall of the metal tube 3. The sawing discs 2 are easily laterally flexible, so that the direction of the saw groove 7 predetermined by the first tooth 6 determines the overall direction of the saw groove 7.

[0034] FIG. 3 shows two possible saw grooves 7, 8 depicted in a metal tube 3. One saw groove 8 is produced in a conventional manner by a sawing disc 2, of which the zero tooth Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4 has a lateral runout d, whereas the second saw groove 7 shown by broken lines has been produced in a cutting operation in which the zero tooth Z.sub.1, Z.sub.2, Z.sub.3, Z.sub.4 has no lateral runout d.

LIST OF REFERENCES

[0035] 1 receptacle

[0036] 2 sawing disc

[0037] 3 metal tube

[0038] 4 distance sensor

[0039] 6 tooth

[0040] 7 saw groove

[0041] 8 saw groove

[0042] α angle

[0043] α.sub.1 angular position

[0044] α.sub.2 angular position

[0045] α.sub.3 angular position

[0046] α.sub.4 angular position

[0047] d lateral runout

[0048] V advancing direction

[0049] L longitudinal direction

[0050] Z.sub.1 zero tooth

[0051] Z.sub.2 zero tooth

[0052] Z.sub.3 zero tooth

[0053] Z.sub.4 zero tooth