WO1995005254A1

WO1995005254A1 - Controller

Info

Publication number: WO1995005254A1
Application number: PCT/EP1994/002739
Authority: WO
Inventors: Michael Späth
Original assignee: Spaeth Michael
Priority date: 1993-08-17
Filing date: 1994-08-17
Publication date: 1995-02-23
Also published as: AU7653794A; EP0700322A1; JPH08505326A; DE4327670C2; DE4327670A1; CA2147242A1

Abstract

A device is disclosed for producing homogeneous spheres from so-called stretch material, made in turn from strips of foil, in particular aluminium foil less than 0.1 mm thick. The device has a feeding reel (2), a strip of foil wound into a roll, a cutting unit (6) with continuously operating cutting roller (3) and pressure roller (4), a stretching unit (6) continuously stretching in the transverse direction, at least one end reel (7) for the finished stretch material and at least one tensioning roller (8, 9) arranged therebetween. In order to ensure a smooth running and a continuous operation, the speed of the motor (10) driving the end reel (7) is controlled. The tensioning rollers (8, 9) mounted between the cutting unit (6) and the stretching unit (5), as well as between the stretching unit (5) and the end reel (7), are designed as sliding, non-driven rollers movable in approximately vertical guides (13) between an upper sensor (11, 11') and a lower sensor (12, 12'). The weight of the tensioning rollers is selected depending on the material, the solidity and the thickness of the foil. The speed of rotation of the motor (10) can be regulated. It is slowed down when the tensioning rollers (8, 9) reach the upper sensor (11, 11') and it is increased when the tensioning rollers (8, 9) reach the upper sensor (11, 11') and it is increased when the tensioning rollers (8, 9) reach the lower sensor (12, 12'), so that the tensioning rollers keep their positions between both sensors (11, 12).

Description

description

Balls made of expanded metal, which in turn is made of thin aluminum foil etc., are filled, for example, as explosion protection in fuel tanks etc. The manufacture of the balls by cutting the aluminum strips in the longitudinal direction, transverse stretching, roughly compressing the strips of expanded metal in the transverse direction, cutting individual sections to length and pressing the sections together to form balls is known in principle, e.g. from German patent applications P 38 14 448 and P 38 16 792.

In order to ensure the smoothest possible process on the one hand and continuous operation of such a machine on the other, even at high speeds of up to 3 m / sec with a material that is as difficult to handle as 70 μm thin aluminum foil, detailed problems must be overcome if the balls should have a negligible committee. Rejects arise when the material distribution within the balls is too uneven and the explosion protection would no longer be guaranteed.

The problem is on the one hand that the aluminum foil used is usually from less than 1/10 mm thick at the desired speeds is already difficult to handle, and handling becomes even more unstable after cutting and transverse stretching, since the finished stretch material undergoes a length reduction of approximately 10% during its transverse stretching, and exactly this length reduction Tensile load in the longitudinal direction can be reversed again.

However, this would on the one hand change the fabric structure inadmissibly and, on the other hand, every lengthening of the material after the transverse stretching acts on the system used as a material stretching in the longitudinal direction. Since the transverse stretching additionally leads to a partially elastic material deformation, the Guerstretched material behaves not only like an elastic, but also like a springy material when longitudinal forces are exerted.

As a result, the achievement of high throughput speeds and the associated exact speed control of the individual drives, that is to say the cutting and pressure rollers of the stretching unit, the cleaning units and the winding reel, become a major problem, since even slightly exceeding the permissible tensile load either increases deformation of the material or tearing of the tape. Likewise, the winding onto the end reel itself must not be carried out with too much tension, since otherwise the layers of the stretch material lying one on top of the other would flatten each other again.

This is added to the fact that with continuous processing of a strip, the requirements for speed control with regard to the speed of the control and its accuracy are in principle greatest when the last drive is used, if a constant starting speed is used at the beginning of the device because add up all the changes in the processing speed that occur in the course of the device — including short-term changes — towards the end, and both rocking and simple balancing can lead to a very irregular, rapidly changing speed profile.

In addition, the material for the individual processing stations must be under a certain minimum tension in the longitudinal direction in order to prevent folding - viewed in the side view - or running up in front of a station, which immediately leads to destruction of the aluminum strip. For this reason it is known in principle to use tensioning rollers when handling running belts.

The existing problems are solved in a generic device by the characterizing features of claim 1. Advantageous embodiments result from the subclaims.

In order to enable the most precise possible speed control of the motor for the end reel, a direct current motor is not used, which is less expensive, but has a too unfavorable torque curve in certain speed ranges, which initially accelerates when accelerating and when the speed threshold is reached too strong a pull occurs with the tape torn off. The DC motor used is directed with a speed monitoring device, for example an optoelectric sensor, which is aimed at an incremental turntable, which is coupled to the motor shaft.

This actual speed is increased or decreased depending on the state of the last previous tensioning pulley, which is determined by the stretching unit and usually also after the cleaning device connected downstream. In this case, a non-driven deflection roller is used as the tensioning roller, which due to its own weight lies in an upwardly open loop of the belt, this tensioning roller being movable in essentially perpendicular guides.

If the end reel runs too fast compared to the last work unit before the tensioning pulley, the tensioning pulley will move upwards in its guides up to a predetermined end stop. However, the height of the tensioning roller between the upper and lower end stops is constantly controlled by a light barrier, which is directed from above onto the tensioning roller or a reflector firmly connected to it, and so that the current altitude of this tension pulley can be measured at any time. The motor of the end reel is accelerated or slowed down by control electronics so that the tensioning roller is kept in a central area and preferably at rest.

In order that the necessary speed range - it must be possible to ramp up continuously from 0 when the machine starts up - can be implemented more easily in terms of control technology, the motor of the end reel is additionally equipped with a primary gear with, for example, four successive speed levels. When the tension pulley passes through a contactless upper end stop, the gearbox switches the motor to the next slower gear stage and, when the lower end stop is reached, to the next faster gear stage.

In addition, short-term speed changes, which rock up very easily, are compensated for between the stretching unit and the tensioning roller just described, in that the stretching material runs in an S-shape over two cleaning brushes which have long and elastic bristles that the elasticity of the bristles has the short-term underside largely compensate for the tensile stress of the expanded material.

In order not to complicate the readjustment of the final reel speed any further, the stretching unit is driven at a constant speed, and instead the speed of the previous cutting unit is regulated. This takes place in turn by means of a first tensioning roller arranged between the cutting unit and the stretching unit, which functions analogously to the second tensioning roller described above, but the speed of the cutting unit or the preceding supply reel should only vary within a small range. Therefore, either the braking force of the end reel or the speed of the cutting unit or both together only when the upper or lower sensors are reached changed, or by the light barrier according to the height of the tension pulley.

The braking force applied to the supply reel at the beginning of the system does not essentially vary according to the intended instantaneous speed of the cutting unit, but rather according to the mass still present on the supply reel and the resulting inertia against changes in speed.

In addition, at the intended high processing speeds, the balls cannot be produced from the expanded material, as in the previously known solutions, by means of a star-shaped, step-wise rotating star into which the sections of the expanded material are introduced on one side, then towards Balls are compacted and fall out of the star again on the other side, since at the intended running speed the flying force adversely affects the entire process and is difficult to predict.

As is known, the stretch material strip is first pushed roughly to the side by pulling it through a calibration opening 34, as a result of which the strip is rippled open in the longitudinal direction. This collapsed band is then cut to certain lengths and the sections thus obtained are deformed into spheres by negative molding.

It was also known in such a ball unit, which consists of several working units next to each other, to perform the cutting by means of two abutting, transversely displaceable knives, which have essentially round, in some cases pear-shaped, aligned openings. The relative set to each other reduces the alignment of the pear-shaped openings, and when the pear shapes are rotated by 180 °, this results in one another when moving in one direction there is a small, circular, free space, while when moving in the other direction, a large, vertical, lenticular and increasingly narrow free space is created, which leads to shearing off when the thickness of the lens approaches 0.

In the present invention, on the one hand, the clamping of the strips pushed together through the calibration opening is carried out at a different location and with separate devices than the cutting off.

The essential point is that the front, free end of the film strip, which has not yet been deflected, is inserted into the cylindrical stamp guide in a stamp block which is open on both end faces. When inserting, but at the latest when deforming to the balls, the rear opening of the punch guide is closed by an end punch 23 with a semicircular concave front face. The front section is cut to length at the beginning and preferably still inside the punch guide by means of knives which can be moved relative to one another and are preferably guided directly in the punch block. After the free end of the endless film strip has been moved back, a front stamp 22 is also introduced into the stamp guide from the front, and the ball is thus formed between the front stamp and the end stamp within the stamp guide. In the case of a plurality of workstations arranged next to one another, for example the front punches are arranged in a row next to one another, specifically on one of two knives 27 which are movable relative to one another and to which all the front punches are applied. In the positions between the front punches, cutting openings are left open in the knives, the cross-section of which can be reduced by pushing the knives against each other in order to clamp the film strip and thereby also be able to be cyclically transported in the longitudinal direction, for example into the punch guide. In order to be able to do this also with the necessary running speed, the stamp block can be displaced in the transverse direction with respect to the knives for clamping and transporting the stretching material and thus also with respect to the front stamps which are mounted on this knife. As a result, the stamp guides of the stamp block can be aligned with the stamps in one work step and with the openings in the clamping device, through which the stretch material is fed into the stamp guides, in the other work step. The stamp block is preferably moved while the knife with the front stamps remains at rest. The front punch and end punch can of course be moved in and out of the punch guide in the axial direction.

To discharge the shaped balls from the stamp block, the end stamp is removed and the front stamp is pressurized with compressed air, whereby the ball is blown out.

For clamping in the plane in front of the front stamp and the actual cutting within the stamp block, the same knives are used, which are arranged in pairs and can be moved against each other, which are used in the plane of the front stamp only for clamping and for axial further transport within the stamp block for actual cutting.

An embodiment according to the invention is described in more detail below by way of example

Fig. 1 is a side view of the expanded material unit and Fig. 2 is a schematic representation of a spherical shape unit.

FIG. 1 shows a side view of the production of the essentially endless stretch material wound on the end reel 7, which is then processed into balls with the device in FIG. 2 away from the roll. The raw material is in the form of a roll wound on a supply reel 2, and during the passage of the film strip 1 through a lubrication unit, then the cutting unit 6, the stretching unit 5 and the suction unit 42 to a widened in the transverse direction and in the longitudinal direction shortened stretch material is processed, which has a thickness about 100 times greater than ^* the starting material.

Due to the various processing processes, the film strip 1 is subjected to different longitudinal speeds. For this purpose, a first tensioning roller 8 is arranged between the cutting unit 6 and the stretching unit 5 and a second tensioning roller 9 is arranged between the stretching unit 5 and the end reel 7.

In order not to make the cumulative changes in speed too rapid, and thereby make it even more difficult to adapt the drive speeds to the individual units, the stretching unit 5 is driven at a constant speed after the machine has started up. Two toothed belts 43 run with their toothed sides against each other in a manner known per se and each hold an outer edge of the film strip 1 between them. At the same time, the film strip runs onto a run-up body or a run-up belt 45, so that the transverse dimensions of the film band increase in the course of the run-up body 45, despite the parallel arrangement of the edges of the film band.

Immediately in front of the stretching unit 5, a downward and upward open loop of the film strip 1 is formed by two deflection rollers 38, 39, the deflection roller 8 resting on the film strip 1 in the lowest point thereof. The weight of this tensioning roller 8 determines the tension of the film strip 1 between the cutting unit 6 and of the stretching unit 5. The speed of the cutting unit 6, which essentially consists of counter-rotating cutting roller 3 and pressing roller 4, is only theoretically equal to the throughput speed through the stretching unit 5, since instantaneous speed differences can arise due to the inherent elasticity and spring action of the film strip 1 . This can be done either by regulating the drive speed of the cutting unit 6 and / or by strengthening or weakening the outlet brake on the supply reel 2, which is also realized by a controllable electric motor.

The regulation of the cutting unit 6 or the braking effect on the supply reel 2 is carried out as a function of the height of the first tensioning roller 8. When the tensioning roller 8 reaches or passes through the upper or lower sensor 11 'or 12', the speed of the preceding units is increased or decreased step by step, for example in 1% steps, until the tensioning roller 8 again in the area between the sensors 11 'and 12'. The sensors 11 'and 12' are electrically coupled to the drive control of the preceding units via a control.

Behind the stretching unit 5, the end reel 7 has to be considered as the most difficult point of the system. The speed of the motor 10 of the end reel 7 depends not only on the working speed of the preceding units and the cumulative changes in speed due to longitudinal expansion etc., but also on the instantaneous diameter of the end reel 7. This diameter, however, is only somewhat circular at the beginning , while with increasing diameter and non-uniform compression of the individual layers of the stretch material, the outer contour becomes more and more out of round and thus there are different speeds of the film strip even in the course of a single revolution of the end reel with constant angular speed. To compensate for both the short-term and the longer-term fluctuations in the throughput speed between the stretching unit 5 and the end reel 7, the film strip 1 is first guided over at least one, preferably two or more cleaning brushes 16, for example in an S-shape, and then after the stretching unit via a second tensioning roller 9, before the film strip 1 sucks off small residual parts in the dust extraction 42 and before the deflection rollers 35/36 with a full end reel 7, cutting to length with the cutting knife 41 is possible.

The cleaning brushes 16 not only remove solid particles, but the brushes are chosen with regard to bristle stability in the longitudinal direction (radial) according to material, thickness and length such that each of the brushes dampens the short-term speed changes. Medium-quality 70 μm thick aluminum foil is a brush with a diameter of approximately 10 cm and a free bristle length of approximately 3 cm.

Since the speed of the film strip 1 can change faster in this rear area of the device than in the front area, the speed of the motor 10 of the end reel 7 is not only controlled when one of the upper or lower sensors 11 or 12 is run through, but also in the area in between. For this purpose, a reflector 15 is fastened to the tensioning roller 9 and is illuminated by a light barrier 14 mounted approximately vertically above it. The light barrier 14 thus continuously controls the height of the tension roller 9 and is connected to the speed control device of the motor 10 via a control. The motor 10 is also continuously checked for its actual speed by optoelectronic scanning of an incremental tachometer disc rotating with the motor shaft. The actual speed is also continuously passed on to the speed control device. In addition, the motor 10 has a stepped transmission with speed ranges that adjoin one another and do not overlap or only overlap very little. If, despite this fine control described, this second tensioning roller reaches the upper or lower sensor 11 or 12, in this case the motor 10 is switched to the next faster or lower gear stage, within which the fine adjustment of the speed is then carried out again by means of the light barrier 14 .

Fig. 2 shows the spherical shape unit, the direction of passage is drawn from left to right with an arrow.

The strip of expanded material is drawn from a supply reel (not shown) or a corresponding number of working units realized from one another from a plurality of supply reels via the calibration openings 34 of the calibration rail 20, which have a strongly rounded inlet, and is therefore strong in the transverse direction pushed together to an approximately round cross-section. This base material is guided through the overlapping opening of the cutting openings 28 of the two first knives 26 and 27, which are movable relative to one another and can thereby change their free passage in order to further compress the base material that is passed through or also to cut it off entirely.

A complete cutting is not intended with the knives 26 and 27, but only a compression, which also makes it possible to pull the base material in the direction of the arrow and back, that is to say in the longitudinal direction. Actual cutting takes place with the identically designed knives 26 ', 27', which are located within the stamp block 24.

The cutting openings 28 are not circular, but have at one point a smaller, additional bulge than a semicircle 29, the semicircle 29 of the cutting Openings 28 of the two knives 26, 27 are arranged in opposite directions.

As a result, in the case of the first knives 26, 27, the cross-section of the two semicircles 29 can be reduced in relation to one another during a movement, as indicated by the arrowheads drawn through them, as a result of which the strand passed through is compressed to about 1/4 of its diameter and thereby clamped at one point becomes. Through a common longitudinal movement of the two knives 26 and 27 in the direction of arrow 46, the strand clamped therein is inserted into a stamp guide 25 flush with the openings 28 and 29, respectively, by bringing the knives 26, 27 closer to the stamp block 24.

After insertion of the free end of the strand, complete cutting off is achieved via the knives 26 ', 27' by relative movement to one another in the direction of the dashed arrowheads, so that a section 34 remains in the punch guide 25. Depending on the working speed, the right, rear end of the punch guide 25 can be open or closed by an end punch 23 placed in front of it. After the section 34 has been cut off, the stamp block 24 is moved in the transverse direction of the arrow 47 by the distance between the cutting openings 28 and the front stamps 22.

The punch guides are now aligned with the front punches 22 and the end punches 23, and at the same time with the cutting openings 28 in the knives 26 ', 27', so that a ball is formed from the section 34 by retracting the punches 22, 23. This is removed from the stamp guide 25 by pulling the end stamp 23, which is attached to a stamp plate with the other end stamps of the other workstations, back out of the stamp guide 25 in the direction of arrow 48 and at the same time from the lowest point of the end-side, hemispherical recess the front stamp 22 Compressed air supplied via the compressed air connection 30 and the ball is thereby blown out of the stamp block.

The advantage of the movement of the stamp block 24 in the transverse direction and the fact that the knife 27 stops in the transverse direction except for the clamping movement lies in the fact that the supply of the expanded metal strip is thereby facilitated by the feeding positions and the immobility of the calibration rail 20 being always constant.

Claims

claims

1. Device for producing homogeneous balls from so-called stretch material, which in turn is produced from foil strips, in particular from aluminum foil with a thickness of less than 0.1 mm, with a supply reel (2) with a foil strip wound into a roll, one continuously Cutting roller (3) and pressure roller (4) working cutting unit (6), a continuously stretching unit (5) stretching in the transverse direction, at least one end reel (7) for the finished stretching material and at least one tensioning roller (8,

9) characterized by a device for regulating the speed of the motor (10) of the end reel (7), the tensioning rollers (8, 9) between the cutting unit (6) and the stretching unit (5) and between the stretching unit (5) and the end reel (7) in approximately vertical guides (13) between an upper sensor (11, 11 ') and a lower sensor (12, 12') displaceable, non-driven rollers are formed, the weight of which depends on the material, strength and thickness the film is selected and - the motor (10) is speed-controllable and is slowed down when the upper sensor (11, 11 ') is reached by the tensioning roller (8, 9) and accelerated when the lower sensor (12, 12') is reached, so that the position of the tensioning roller remains between the two sensors (11, 12).

2. Device according to claim 1, characterized in that ß the sensors (11, 11 ', 12, 12') are designed as non-contact limit switches and the speed of the motor (10) is controlled as a function of the current height of the tensioning roller.

3. Device according to claim 2, d a d u r c h g e k e n n z e i c h n e t, d a ß the height of the tension roller (9) is measured by a substantially perpendicular light barrier (14) on the housing of the device and a reflector (15) on the tension roller.

4. Device according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t, d a ß the height of the second tensioning roller is used to regulate the motor (10).

5. Device according to one of the preceding claims, characterized in that the motor (10) of the end reel (7) can be operated in several speed stages by means of a gear, and when the upper or lower sensor (11 or 12) reaches the tensioning pulley (9) is switched to the next faster or slower gear stage of the motor (10).

6. Device according to one of the preceding claims, characterized in that the stretching unit (5) is operated at a constant speed and the speed of the cutting unit (6) can be varied at least in stages and is changed when the upper or lower sensor is reached ( 11 'or, 12') of the first tensioning roller (8).

7. Device according to one of the preceding claims, characterized in that the supply reel (2) is equipped with a braking device with a variable braking effect and the braking effect is varied depending on the diameter of the supply reel (2) and / or the position of the tensioning roller (8).

8. Device according to one of the preceding claims, characterized in that the cross-stretched film strip (1) runs between the stretching unit (5) and the second tensioning roller (9) via at least one cleaning brush (16), the bristles of which are sufficiently long and elastic to to compensate for short-term changes in the tension in the film strip (1) in this section by the elasticity of the bristles

9. Device according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t, d a ß as a motor (10) on the end reel (7) a DC motor is used.

10. Device according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t, d a ß the motor (10) is operable in four speed levels between zero and 160 m / min.

11. Device according to one of the preceding claims with a spherical molding unit which forms spheres from stretched-together sections (34) of stretched material which are cut in the transverse direction and cut to the appropriate length by means of hemispherical shapes, d a d u r c h g e k e n n z e i c h n e t, d a ß

- the balls (32) are made in an approximately cylindrical punch guide (25) by moving against one another the stamping (22, 23) of approximately hemispherical concavity on the end faces,

the front punch (22) acting from the feed direction of the stretch material is fastened on the second knife (27),

- Wherein between the individual front punches (22) for the individual work stations on the second knife (27 ') are fastened next to one another, cutting openings (28) are arranged between the front punches (22), a first knife (26) is guided so that it can be displaced parallel and closely to the second knife (27) and - the punch block (24 ), in which the stamp guides (25) are formed, transversely to the direction of travel of the material and the main direction of movement of the stamps (22, 23) from an aligned position of the stamp guides (25) to the stamps (22, 23) in an aligned position to the Cutting openings (28) is displaceable.

12. Device according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t, d a ß the front punches (22) have a compressed air connection (30) which opens into the rear region of the concave, front-side recess.

13. Device according to one of the preceding claims, characterized in that ß a first knife (26 ') and a second knife (27') with cutting openings (28) in the stamp block (24) transverse to the passage direction of the stamp guides (25) relative to each other are slidably arranged.