GB2144670A

GB2144670A - Numerically guided disc cutter

Info

Publication number: GB2144670A
Application number: GB08419587A
Authority: GB
Inventors: Matti Johannes Lukkari; Reino Ilmari Skarp
Original assignee: Nokia Oyj
Current assignee: Nokia Oyj
Priority date: 1983-08-12
Filing date: 1984-08-01
Publication date: 1985-03-13
Also published as: JPS6099513A; IT1176558B; SE8404060L; FI832914A0; FR2550486A1; FI832914A; DE3428948A1; FI69771C; IT8422223A0; SE8404060D0; FI69771B; GB8419587D0

Abstract

Upper and lower cutting blade units 1, 2 are first adjusted roughly and independently of each other, by means of numerically guided driving screws (14,27 Fig. 1), and then accurately by means of a measuring slide 54 guided numerically and substantially without play by a driving screw 60. The slide 54 carries a sensor 56a, 56b co-operating with measuring parts 68, 69 on the blade bodies, viz. elements of the same width as the cutting edge of the blades, and as a first step in the adjustment the slide is moved under numerical guidance to the exact, calculated position for the blade unit in question. The unit is then moved approximately into position by its driving screw, after which co-operation between the sensor 56a, 56b and the measuring parts 68, 69 completes the accurate adjustment. <IMAGE>

Description

SPECIFICATION Numerically guided disc cutter The present invention relates to a numerically guided disc cutter especially for longitudinal cutting of a metal or plastic web, the cutter comprising a body, upper and lower cutting blade units, means for driving the cutting units and means for adjusting the cutting units.

In disc cutters of this kind a re-adjustment of the disc blade arrangement is required when the width of the webs is changed and is carried out, e.g. by changing the interspace between the blades in the cutter or by using so-called exchanged blade series, that is to say, the blades are fixed to collars that are as long as the cutter is wide. By using two or more collar pairs and blade series, the exchange blade series can be readily adjusted for new web widths on the outside of the cutter. When new web widths are required in the cutter, the exchange blade series already adjusted is fitted to the cutter.

Furthermore, solutions are known where the whole cutter is changed for another cutter, the blade series of which is ready adjusted.

The object of the invention is to provide a numerically guided disc cutter and a method for adjusting its cutting units, with which the adjustment can be performed more reliably and quickly than previously and by using means which cost considerably less than previous means. In the method according to the invention, the cutting units are adjusted independently of each other first roughly by means of a numerically guided transport means and then after the rough adjustment, the cutting units are accurately adjusted by means of a transport element moving a measuring slide substantially without play and guided numerically in place.

Because the measuring slide is independent of the transport means of the cutting units, the method according to the invention can preferably comprise an adjustment control of the position of the blades made by means of the measuring slide.

Because the cutting units can be adjusted independently of each other by means of the method, it is preferable that, during the adjustment, the upper and lower cutting units are separated from each other in the vertical direction, whereat also the alternating arrangement of the upper and lower cutting units can be changed.

A numerically guided disc cutter in accordance with the invention, particularly for the longitudinal cutting of metal and plastic webs, comprises a body, upper and lower cutting blade units, means for driving the cutting units and adjusting means for the cutting units comprising transport means fixed to the body for the upper and lower cutting units, clutches and locking elements contained in the cutting units and by means of which the cutting units are connected to the transport means and to the body respectively, and a pulse sensor connected to the transport means for following the position of the cutting units, the adjustment means also comprising a measuring slide arranged to be moved substantially without play on a transport element connected to the body and having a second pulse sensor for following the position of the measuring slide, the slide carrying a sensor co-operating with the cutting units.

The adjustment means preferably comprise means either for elevating the upper cutting units or for lowering the lower cutting units. This is preferably achieved with hydraulic cylinders returnable by spring force which, when not pressurised, keep the lower cutting units in the lower position.

A disc cutter according to the invention and its method of adjustment will now be described in more detail, with reference to the accompanying drawings, wherein: Figure 1 shows a section of the disc cutter seen from the infeed direction of the web; Figure 2 shows the disc cutter seen from the infeed direction of the web; Figure 3 shows a cross section of the disc cutter along line III - Ill in Figure 2; Figure 4 shows a measuring slide forming part of the disc cutter, seen from above; Figure 5 shows a section along line V - V in Figure 4; Figure 6 shows a section along line VI - VI in Figure 4; Figure 7 shows the upper cutting unit of the disc cutter; Figure 8 shows the lower cutting unit of the disc cutter; Figure 9 shows one arrangement of the cutting units of the disc cutter; and Figure 10 shows another arrangement of the cutting units of the disc cutter.

In Figure 1, a section of a disc cutter according to the invention is shown seen from the infeed direction of the web to be cut. The cutter has a number of upper cutting units 1 and lower cutting units 2. Upper cutting units 1 are positioned on slide bars 3 connected to a moving body 4. Body 4 can be moved in the vertical direction in order to adjust the vertical blade interspace by means of a handle 5, a shaft 6, spiral gears 7 and a thread on collar nuts 8.

The upper cutting units are substantially identical and comprise, as appears from Figure 7, a ringlike cutting blade 9 and a hub 10 to which the blade is fastened. The hub is mounted on a protruding shaft 11 which is fixed to the body 12 of the cutting unit. To the body of the cutting unit the connection system of the unit is also attached, which comprises a clutch 13 (Figure 7) for gripping the transport screw 14 of the units and locking elements 15 for locking the unit to slide bars 3. Clutch 13 is of the type conventionally used within the trade comprising clutch halves 16 and 17 and a hydraulic cylinder 18 returnable by spring force pressing them against each other and also against transport screw 14. Between clutch halves 16 and 17 springs (not shown) are also arranged for keeping the clutch halves separated from each other when cylinder 18 is not pressurised.Locking elements 15 comprise hydraulic operated cylinders 19 and brake parts 20, e.g. of brass, pressing against slide bars 3 and locking the cutting unit in place when the cylinders. 19 are pressurised.

Lower cutting units 2 which are substantially identical are arranged on slide bars 22 fixedly connected to the body 21 of the disc cutter. Lower cutting units 2 comprise, as appears from Figure 8, a ring-like cutting blade 23 and a hub 24 to which the blade is fastened. Hub 24 is mounted on a protruding shaft 25 fixed to the body 26 of the cutting unit. A clutch system similar to the one in upper cutting unit 1 is connected to body 26 and comprises a clutch 28 (Figure 8) for gripping a transport screw 27 and locking elements 32 for locking to slide bars 22. Connector 28 comprises connector halves 29 and 30 and a hydraulic cylinder 31 returnable by spring force pressing them against each other and also against transport screws 27 and springs (not shown) keeping the connector halves separated from each other when the cylinder 31 is not pressurised.Locking elements 32 comprise hydraulic cylinder 33 and brake parts 34.

Also a hydraulic cylinder returnable by spring force is connected to the body 26 of lower cutting unit 2 for elevating the cutting unit to the cutting position. Body 26 then slides along slide bars 37 formed between the sides of body 26 and body parts 36.

Transport screws have been used as the transport device of the upper and lower cutting units in the illustrated embodiments. The thread form of the screw can vary being, e.g. an M thread or a circular thread, but a trapezoid thread is probably the most economical because of its availability on the market. Instead of a transport screw many other transport means can be used, such as a toothed belt, flat belt, cone belt, chains, cylinders or even manual transport of the cutting units.

In the embodiment according to Figure 1, transport screws 14 and 27 of the upper and lower cutting units are mounted on the body and are driven by means of bevel gear pairs 38 and 39 and a shaft 40 in a motor 41. To the end of transport screw 27 a pulse sensor 42 is attached for following the rotation of the transport screw.

Cutting blades 9 of upper cutting unit 1 are driven by means of a toothed belt wheel 43 fixed to the hub 10 of the blade and a toothed belt 45 and a toothed belt wheel 49 mounted on the body of the cutting unit. Toothed belt wheel 49 is in connection with a splined shaft 47 which in its turn is connected to a motor 50 through the extension of shaft 47 and a universal joint 79.

In a similar manner the lower cutting units 2 are driven by means of a toothed belt wheel 44 fixed to the hub 24 of the blade, a toothed belt 46 and a toothed belt wheel 51 mounted on the body of the cutting unit. Toothed belt wheel 51 is in connection with a splined shaft 48 which through the extension of shaft 47 and toothed belt wheel pair 52 is in connection with motor 50. Between motor 50 and the extension of shaft 47 a gear box 53 is further arranged, on both sides of which there are clutches (not shown).

Splined shafts 47 and 48 as well as transport screw 27 are mounted on the body 21 of the disc cutter. The transport screw 14 of the upper cutting units is mounted on the supporting body 4 of the upper cutting units which body rests on body 21 by means of spiral gears 7.

Seen from the infeed direction, as appears from Figures 2 and 3, a measuring slide 54 is arranged in front of the disc cutter, which slide comprises (Figure 5) a body 55 and sensors 56a and 56b arranged on springs 55' for the upper and lower cutting units. Body 55 rests on the body 21 of the disc cutter by means of slide bars 57 and 58. The measuring slide is arranged to move on slide bars 57 and 58 substantially without play by means of a transport element such as a ball-jointed screw and nut combination. This combination comprises a ball-jointed screw 60 supported by bearings 58 and 59 to the body of the disc cutter and a nut 61 arranged to move substantially without play by screw 60 on the measuring slide. To one end of screw 60 a motor 63 is connected through a clutch 62 which drives screw 60 through a step-down gear (not shown).To the other end of screw 60 a pulse sensor is connected for following the position of measuring slide 54 on the basis of the rotation of the screw. The transport of measuring slide 54 substantially without play can be realised also with a rack and pinion, the pinion and its driving motor and the measuring slide attached thereto moving along the rack, and also by means of two toothed belt wheels and a toothed belt, the measuring slide being connected to the toothed belt.

As appears from Figures 1 and 2, the disc cutter includes a work area, that is an area where the cutting units can be in the operative position, and a storage area for the cutting units, a magazine (to the right in Figures 1 and 2).

The starting position for the operation of the disc cutter is when cutting units 1 and 2 are positioned in the magazine at a point determined by corresponding limit switches 65 and 66 (Figures 4 and 6). Measuring slide 54 in its turn is positioned in the influence area of limit switch 67 (Figure 2).

Connectors 28 of the lower cutting units are open and locking elements 32 are shut and the cutting units are in their lower position. Connectors 13 of the upper cutting units are correspondingly open and locking elements 15 shut.

The measuring function of the measuring slide is based on the fact that the rims of all the cutting blades are ground to the same width as the measuring parts 68 and 69 of the blades on the blade bodies (Figures 4 and 5).

The adjustment of the cutting units can be carried out in two different ways so that both edges of the cutting blades can function as cutting edges.

Further the adjustment of the cutting units is always carried out so that the edges of each web to be cut are cut in the same direction, whereat the straightening of the edges of the webs does not have to be done and the webs are received from the machine on the same level.

When adjusting the cutting units, measuring slide 54 is moved by means of screw 60 and servomotor 63 to a point at a reference measure part 70 which is a vertical bar functioning as a reference measuring part for sensor 56a as well as for sensor 56b. Because the reference measuring part is common to both, a possible angular error in sensors 56a and 56b can also be detected. The position counter (not shown) of the measuring slide is zeroed at this point.

The absolute positions of the cutting edges of the blades can now be calculated by means of the following formulae, when the desired widths of the webs are I,, l2...lt, the blade interspace in the lateral direction of the cutting blades is It, the interspace between the reference measuring part and the zero line or the edge of the web to be cut is I, the possible angular error of sensors 56a and 56b is K and when the blade units are numbered 1 to 5 and a sub-index Y is used for the upper blade and a subindex A for the lower blade and the arrangement of the blades is according to Figure 9:: liy = I + Ii - It liA = l + Ii + K 12Y = 11A + 12 - It 12A = liv + 12 + It 13Y = 12Y + 13 - It = = 12A + 13 + It l4A = 13A + 14 - It 14Y = 13Y + 14 + It 15Y = 14Y + 15 - It 15A = l4A + It + It Now measuring slide 54 is moved to the absolute position of each blade.Next the desired cutting unit is moved roughly and quickly in place by means of either transport screw 14 or 27 depending on whether it is a question of the upper cutting unit or the lower cutting unit on the basis of the number of pulses given by pulse sensor 42. When the cutting unit thus has been placed approximately in place and into the measuring area of the sensors of the measuring slide preferably containing one real measuring sensor and two approaching sensors, the cutting unit is further moved by either transport screw 14 or 27 slower and exactly into its right position as regards the measuring sensor. Measuring sensors 56a and 56b of the measuring slide are preferably inductive sensors, by means of which a very high repeatability of measurement accuracy is achieved.As appears from Figure 5, measuring sensor 56a or 56b is positioned in a measuring situation very close to the measure parts 68 or 69 of the cutting unit or even rubs mechanically against it to the extent admitted by the supporting springs of the sensors.

In this way all desired cutting units are moved into desired positions and the additional cutting units stay in the storage area for their limit switches. A limit switch 71 (Figure 2) prevents transport of the measuring slide from exceeding the cutting area. When all desired cutting units are in place, their position can, when wished, be controlled by means of the measuring slide as follows: The measuring slide is moved to a point at reference part 70 and the position counter is zeroed. By means of the measuring slide the edge of a measure part corresponding to the cutting edge of each blade is looked for and the output of the position counter is compared to the calculated absolute value. Here a small error tolerance can be accepted, otherwise the adjustment of the cutting unit in question is corrected.

In the second cutting combination, according to Figure 10, the left hand edge of the first upper blade cuts differently from the cutting combination in Figure 9, so the blades are worn evenly on both edges.

When all blades are in place and within the tolerance, the measuring slide can be moved to the right edge on the storage area and the lower blades can be elevated. After this, the real cutting can begin.

Because of the spring adapting of measuring sensors 56a and 56b and the resultant short distance (0.lmm) of the measure part and the measuring sensors and use of the inductive sensors, a repeatability of 0.001 mm is reached in the measuring. The same accuracy can be reached also by using an optic sensor. Thus the cutting unit can be located as regards the sensor of the probe with substantially the same accuracy. When adjusting the upper and lower cutting units an accuracy of 0.05 mm can be estimated to be obtained. The accuracy obtained depends essentially on the accuracy with which the measure parts of the cutting units are mounted at the point of the blades.

As an example a system can be examined where the transport of measuring slide 54 occurs by means of screw 60 without play, the rise of which is 5.0 mm and diameter 25.0 mm. The screw is rotated by DC servomotor 63 the maximum speed being 600 revolutions per minute. On the shaft of motor 63 pulse sensor 67 is mounted giving 5000 pulses per revolution. The measurement resolution is 0.001 mm and when a measuring sensor is used, having a repeatability accuracy of, e.g. 0.001 mm, the cutting units can be adjusted with an accuracy of 0.005 mm.

When the driving motor 41 of lateral transport shaft 40 and the transport screw 14 and 27 of the cutting units 1 and 2 is a servomotor, the maximum rotation speed of which is 3000 revolutions per minute, and the gear ratio of bevel gear pairs 38 and 39 is 3:1, the maximum rotational speed of transport screw 14 and 27 is 1000 revolutions per minute. When pulse sensor 42 at the end of transport screw 27 gives 50 pulses per turn and the rise of transport screws 14 and 27 is 5.0 mm, the measuring resolution is 0.1 mm. Hereby the accuracy of the rough adjustment of the cutting units defines the sum, 2 to 3 mm, of the recognising distances of limit connectors 65 alt. 66 of the measuring accuracy of the pulse sensors.

From these inexact positions the cutting units are moved to a point at sensors 56a or 56b, whereat the adjustment accuracy of the cutting unit is as described about 0.005 mm.

Claims

1. A method for adjusting the cutting blades of a numerically guided disc cutter, particularly for longitudinal cutting of metal or plastic webs, the disc cutter comprising upper and lower cutting blade units, means for driving the cutting units and means for adjusting the cutting units, and in which method the cutting units are first positioned roughly, independently of each other by means of numerically guided transport means, and then after the rough adjustment, the cutting units are accurately adjusted by means of a transport element moving a measuring slide substantially without play and guided numerically in place.

2. A method according to claim 1 in which the accurate adjustment comprises a control of the position of the blades by means of the measuring slide.

3. A method according to claim 1 in which in the accurate adjustment the transport of the blades occurs by means of the said adjusting means.

4. A method according to any one of the preceding claims, in which during the adjustment the upper and lower cutting units are moved apart from each other in the vertical direction.

5. A numerically guided disc cutter, particularly for the longitudinal cutting of metal and plastic webs, the cutter comprising a body, upper and lower cutting blade units, means for driving the cutting units and adjusting means for the cutting units comprising transport means fixed to the body for the upper and lower cutting units, clutches and locking elements contained in the cutting units and by means of which the cutting units are connected to the transport means and to the body respectively and a pulse sensor connected to the transport means for following the position of the cutting units, the adjustment means also comprising a measuring slide arranged to be moved substantially without play on a transport element connected to the body and having a second pulse sensor for following the position of the measuring slide, the slide carrying a sensor co-operating with the cutting units.

6. A disc cutter according to claim 5, in which the adjustment means includes means either for elevating the upper cutting units or for lowering the lower cutting units during the time of the adjustment.

7. A disc cutter according to claim 6 in which the means for returning the lower cutting units to the operative position are hydraulic cylinders returnable by spring force.

8. A disc cutter according to any one of claims 5 to 7 in which the sensor carried by the measuring slide is an inductive sensor.

9. A disc cutter according to any one of claims 5 to 7 in which the sensor carried by the measuring slide is an optic sensor.

10. A disc cutter according to any one of claims 5 to 9 in which the transport element for driving the measuring slide substantially without play is a ball-jointed screw.