EP3943263B1 - Method for automatically adjusting the cutting gap of a slicer and cutting machine suitable therefor - Google Patents

Description

I. Area of application

The invention relates to slicing machines for slicing strand-shaped food products, so-called calibers, into slices, in particular high-speed slicing machines such as slicers, which are used primarily for slicing sausage or cheese calibers.

II . Technical background

The always correct, automatic adjustment of the cutting gap, i.e. the distance between the knife plane in which the cutting edge of the knife rotates, and a counter edge, especially measured in the direction of the knife's axis of rotation, is essential for both the cutting result and the durability of the knife:
If the cutting gap is too large, the slice will increasingly be chopped off instead of cut, resulting in visually unattractive slices. If there is no cutting gap, i.e. if the knife scrapes against the opposite edge, the knife will become blunt more quickly.

The automatic adjustment of the cutting gap should be possible, if possible, while the knife is rotating, so that the very fast-running knife does not have to be completely stopped in its rotation every time.

Furthermore, because when the knife approaches the caliber guide, e.g. a cutting frame on which the counter edge is formed, the initial contact does not necessarily have to be between the cutting edge and the counter edge, but also between areas of the knife lying away from it on the one hand and /or the caliber guide on the other hand.

To adjust the cutting gap, it is known to approach the knife, which is initially still spaced from the counter edge, by means of an adjusting device in the direction of the knife axis, the axial direction, to the counter edge and to detect the contact and as a starting position or reference position for the subsequent axial spacing of the knife from the opposite edge to a specified target cutting gap.

It is from the EP 1 409 210 B1 known to measure the current consumption of the electric motor of the adjusting device and, if it increases, to conclude that there is contact. This is done with the knife stationary and not rotating.

However, due to the usually high gear ratio of the electric motor for the adjustment device, such an increase only occurs at relatively high forces acting transversely on the knife and transversely to its knife plane through the caliber support.

From the EP 2 580 033 B1 It is known to measure the drag error of the knife motor that sets the knife in rotation during slicing and to interpret its increase as contact between the knife and the caliber guide.

However, this requires a motor control that outputs the following error. This is the case with a following error control of the knife motor, which, however, has the disadvantage that if an impermissibly high following error is detected, the actual speed does not only have to be increased by increasing the power supply until the target speed is reached - which is true would only keep the impermissibly high following error constant - but the actual speed must be increased above the target speed in order to completely eliminate the following error or reduce it to a permissible, lower value.

This can result in undesirably high actual speeds and a sub-optimal cutting pattern.

In both cases, contaminants adhering to the cutting edge of the knife or the counter edge can completely distort the measurement result, especially in the former procedure with a non-rotating knife.

In this context, it is clear from the DE 10333661 A1 and the WO 2005/009 696 A1 It is known to detect the torque of the rotary drive for the knife and to select an axial position as the zero point of the knife in the axial direction at which the knife no longer touches the cutting glasses in order to be able to adjust the cutting gap based on this.

These documents form the basis of the preamble of claim 1.

III. Description of the invention a) Technical task

It is therefore the object of the invention to provide a method for adjusting the cutting gap and a slicing machine suitable for this purpose, which eliminates these disadvantages.

b) Solution to the task

This object is solved by the features of claims 1 and 11. Advantageous embodiments emerge from the subclaims.

With regard to the method for automatically adjusting the cutting gap, this task is solved, among other things, in that before contacting the caliber guide through the knife, i.e. before or when the rotating knife, which is running idle without contact with the material to be cut, approaches, the idle torque with which the knife motor drives the knife is measured, and the approach movement of the knife is then stopped when there is an increase this idle torque by at least a fixed 1. Torque difference is determined or a specified absolute torque threshold is at least reached or exceeded.

As a rule, the idle torque increases because the knife has come into contact with the caliber guide and is braked by it.

This procedure can advantageously be carried out with a rotating knife, in particular at a speed of the knife of 50 rpm to 500 rpm, preferably from 50 rpm to 150 rpm.

The knife usually has a maximum radius of 300 mm to 600 mm.

Another advantage is that even a very slight contact, i.e. with low mutual contact pressure between the knife and the caliber guide, leads to a significant increase in torque, meaning that pressing against each other can be detected very early.

For this purpose, the knife is used with an approach rate of at most 0.1 mm per knife revolution, better at most 0.08 mm per knife revolution, preferably with an approach rate between 0.1 mm and 0.01 mm, better between 0.08 mm and 0.03 mm, moved towards the caliber guide in order to be able to stop the approach before excessive forces from the caliber guide act on the knife and distort it.

The approach direction in which the knife is moved towards the caliber guide usually corresponds to the direction of the knife axis around which the knife rotates, and also usually corresponds to the feed direction in which the caliber is pushed forward towards the knife plane for slicing , but could also be at an acute angle to one or both of these.

For the purposes of the present invention, it is assumed that the direction of the knife axis is identical to the feed direction.

It is further assumed that the approach direction and the separation direction are exactly opposite directions.

It is further assumed that the approach direction and/or the spacing direction correspond to the direction of the knife axis and/or the feed direction.

This makes it easier to control the movements of the slicing machine.

As soon as contact has been established in this way and the approach movement has been stopped, the knife is moved back against the approach direction in the spacing direction by a distance that corresponds to the desired size of the cutting gap.

In this way, the cutting gap can be adjusted to the desired size very quickly and without any manual effort.

The caliber guide is often a circumferentially closed caliber guide, a so-called cutting frame, and in many slicers it is movable, at least transversely to its direction of passage, the feed direction of the caliber.

Therefore, such an automatic adjustment of the cutting gap can be carried out after each adjustment of the caliber guide and/or before cutting a new caliber, but as a rule the adjustment is only carried out when the knife or the caliber guide, e.g. the cutting glasses , was changed.

Because with such a movement, an undesirable movement in the direction of the knife axis or the knife plane can also occur and/or an undesirable pivoting of the front surface of the caliber guide, and thus a deviation from their parallel position to the knife plane, which should be maintained so that the actually set cutting gap is present between the cutting edge of the knife and the counter edge of the caliber guide.

In order to ensure that the increase in the idle torque was caused by the knife running into the front surface of the caliber guide, according to the invention, after stopping the approach movement, several, in particular at least 3, better at least 5, better at least 10 knife revolutions are carried out with the power supply unchanged and the approach movement stopped - i.e. the knife is at a standstill in the direction of the knife axis - and it is checked whether the idle torque remains approximately the same, i.e. does not decrease by more than a specified 2nd torque difference.

Such a decrease would indicate that the cause of the previous increase in idle torque was a contaminant, such as a meat fiber, between the knife and the caliber guide, which was thrown away due to the further knife revolutions and no longer brakes the knife.

If such a reduction in the idle torque by at least the 2nd torque difference is not detected, the return movement of the knife in the spacing direction is carried out as described.

This can also be done completely automatically and therefore unmanned. Preferably, while the knife is being delivered in idle mode for the cutting gap adjustment, the power supply to the knife motor is controlled depending on the relative changes that occur in the rotational speed of the knife during a knife revolution.

Such fluctuations in the rotational speed occur in practice and are caused by uneven friction in the motor bearing or the existing seals around the circumference of the knife shaft, for example.

If the rotational speed changes within one blade revolution by more than a specified tolerance difference between the lowest and highest occurring rotational speed, the power supply is increased, if the rotational speed has dropped to an impermissible level, in the opposite case it is reduced, in each case until the rotational speed is back within the permissible range lies.

Alternatively, the power supply can also be controlled during the feed of the knife in idle mode for the cutting gap adjustment depending on the absolute deviations of the actual rotation speed from a target rotation speed during a complete rotation of the knife. If a specified tolerance deviation from the actual rotation speed is exceeded, the power supply is increased if the rotation speed has dropped to an unacceptable level, and reduced if the opposite is the case, in each case until the rotation speed is back in the permissible range.

Such a so-called speed control of the motor is easier to implement because it is less sensitive than, for example, a lag error control, in which, if the rotation of the blade lags behind the target state, the control system aims to catch up and compensate for the lag error and for this purpose the speed of the blade must exceed the intended target speed, at least for a limited time, which can, however, have a negative influence on the adjustment process.

A general problem with adjusting the cutting gap by moving the knife to the front surface of the caliber guide until it makes contact is that with the known methods, at least automatically, it cannot be determined whether the first contact actually took place between the cutting edge of the knife and the front surface of the caliber guide at its opposite edge or at least close to its opposite edge, or far away from it.

On the knife side, contact can also be made not via the cutting edge, but via a knife area located away from the cutting edge.

This can occur if the front of the knife facing the caliber guide is unacceptably convexly curved or the cutting edge is not in one plane or the front surface of the caliber guide facing the knife is unacceptably convexly curved or - which is the more common case - the front surface Although it is flat, it does not run parallel to the plane of the knife in which the cutting edge moves, but at a slight angle to it.

Then the cutting edge of the knife will be the first to reach the front surface of the caliber guide, but not at or near its opposite edge, but far away from it, at the beginning of the - viewed in the axial direction - intersection of the cutting edge with the front surface or at the last point of this intersection.

Then, by moving the knife back, a gap is set between this first point of contact on the front surface and the knife edge, but the actual cutting gap between the counter edge and the knife edge is then in reality larger.

In order to avoid this, the invention can automatically check whether there is sufficient parallelism between the knife plane and the front surface of the caliber guide, in particular the cutting glasses.

For this purpose, it is checked whether, for each revolution carried out at idle speed - with the axial approach of the blade stopped - the idle torque always increases significantly - i.e. by more than a predetermined torque difference value - at the same rotational position of the knife, which indicates that contact of the knife on the front surface does not take place over its entire area simultaneously, but only partially in one area of this front surface.

By determining the rotational position and/or the location of this area, it is also possible to determine the tilt axis around which the front surface of the product guide is impermissibly tilted to the knife plane, and this information can be output to the operator to facilitate readjustment of the product guide.

Typically, a slicing machine has a knife with a cutting edge that can be rotated about a knife axis and is driven by a knife motor, as well as a caliber guide with a front side along which the knife moves with its cutting edge, as well as an adjustment device for adjusting the knife in the direction of the knife axis.

In such a slicing machine, the existing task is solved by the machine including a torque sensor with which the torque with which the motor drives the knife or with which the knife rotates can be measured.

According to the invention, the controller, which controls at least all moving parts of the machine, must be set up to carry out the method described above.

The caliber guide, usually a cutting frame surrounding the product caliber, is preferably movably attached to the base frame of the machine.

On the one hand, there is a possibility of movement of the caliber guide transverse to the axial direction in order to control the contact force of the caliber on the caliber guide.

According to the invention, it is preferably possible to move the caliber guide in such a way that the angular position of its front surface to the knife plane can be changed in order to be able to restore this parallel position in the event of a deviation from the desired parallel position.

This is usually done manually using appropriate adjustment elements such as set screws.

This makes it possible to readjust the caliber guide instead of replacing it, so that spare parts consumption remains low and machine downtimes can be kept short.

c) Embodiments

Figur 1a:

eine Aufschneide-Maschine in Form eines Slicers gemäß dem Stand der Technik in perspektivischer Ansicht,

Figur 1b:

in der Seitenansicht einen vereinfachten vertikalen Längsschnitt durch die Aufschneide-Maschine der Figur 1a , in dem die verschiedenen Förderbänder besser zu erkennen sind, da die in Blickrichtung davorliegenden Abdeckungs- und Verkleidungsteile vor der Schnittebene liegen, mit in die Aufschneidestellung hochgeklapptem Zufuhrband,

Figur 1c:

eine Detailvergrößerung aus dem Längsschnitt der Figur 1b , aber mit in die Beladestellung herabgeklapptem Zufuhrband und fortgeschrittenem Aufschneide-Zustand des Produkt-Kalibers,

Figur 2:

in der Seitenansicht aus dem Längsschnitt der Figur 1c , aber demgegenüber vergrößert, dass Abtrennen von Scheiben,

Figuren 3a - c:

unterschiedliche Stellungen des Messers zur Schneidbrille in der Seitenansicht,

Figuren 4a - d:

unterschiedliche Drehlagen des Messers zur Schneidbrille betrachtet in axialer Richtung,

Figur 5a:

ein Drehmoment-Diagramm,

Figur 5b:

ein Geschwindigkeits-Diagramm.

Embodiments according to the invention are described in more detail below by way of example. They show:

Figure 1a:

a slicing machine in the form of a slicer according to the prior art in perspective view,

Figure 1b:

in side view a simplified vertical longitudinal section through the slicing machine of the Figure 1a , in which the various conveyor belts can be seen better, since the cover and cladding parts in front of them are in front of the cutting plane, with the feed belt folded up into the cutting position,

Figure 1c:

a detailed enlargement of the longitudinal section of the Figure 1b , but with the feed belt folded down into the loading position and advanced slicing condition of the product caliber,

Figure 2:

in the side view from the longitudinal section of the Figure 1c , but in contrast, increased that cutting of discs,

Figures 3a - c:

different positions of the knife to the cutting glasses in the side view,

Figures 4a - d:

different rotational positions of the knife relative to the cutting glasses viewed in axial direction,

Figure 5a:

a torque diagram,

Figure 5b:

a speed diagram.

The Figure 1a shows a perspective view of a slicer 1 for simultaneously slicing several product calibers K next to each other and, if necessary, storing them in shingled portions P from several slices S each - see Figure 2 - with a general horizontal direction 10* of the material to be cut through the slicer 1 from right to left.

Figure 1b shows a - simplified by omitting details that are less important for the invention - vertical section through such a slicer 1, cut in the longitudinal direction 10, the feed direction of the calibers K to the cutting unit 7 and thus the longitudinal direction of the calibers K lying in the slicer 1, and thus also cut in the general direction of flow 10*.

The basic structure of a slicer 1 according to the prior art is that a cutting unit 7 with a sickle knife 3 driven in rotation about a knife axis 3 'by a knife motor 22 has several, in this case four, lying next to one another transversely to the feed direction 10 Figure 1a not shown, product caliber K are fed from a feed unit 20, from the front ends of which the rotating sickle knife 3 simultaneously separates a slice S.

For this purpose, the feed unit 20 comprises a feed conveyor 4 in the form of an endless, revolving feed belt 4, with the calibers K lying next to one another across the width of this feed conveyor 4 in this transverse direction 11 through elevations 15 which extend from the feed belt 4 protrude outside, be positioned.

For cutting the product caliber K, the feed conveyor 4 is located in the Figures 1a , b shown inclined position with a low-lying cutting-side, front end and a high-lying rear end - the slicing position - from which it can be folded down about a pivot axis 4' running in the first transverse direction 11, which is located near the cutting unit 7, relative to the base frame 2 of the machine into a Figure 1c shown, approximately horizontal loading position, in which new product calibers K are already placed on the feed conveyor 4, while the remainder KR of the previous calibers K are still held on the gripper 14 and between the upper and lower product guides 8, 9 and are cut open.

The rear end of each caliber K located in the feed unit 20 - see Figure 1b - is held in a form-fitting manner by a gripper 14a - d with the aid of gripper claws 16. These activatable and deactivatable grippers 14a - 14d are attached to a common gripper unit 13, which can be guided in a controlled manner along a rod-shaped gripper guide 18 in the feed direction 10, whereby the actual feed speed of the calibers K is brought about by a so-called upper and lower product guide 8, 9, which each consist of an endless, rotating guide belt and which engage the top and bottom of the calibers K to be cut at their front end areas near the cutting unit 7, whereby all moving parts of the machine 1 are controlled by its control 1 *.

For the cutting, the front ends of the calibers K are guided through a so-called spectacle opening 6a - d, which is available for each caliber and is formed in a plate-shaped cutting spectacle 5, with the cutting plane immediately in front of the front, diagonally downward-pointing end face of the cutting spectacle 5 3" runs, in which the sickle knife 3 rotates with its cutting edge 3a and thus separates the protrusion of the caliber K from the cutting frame 5 as disks S. The cutting plane 3" runs perpendicular to the upper run of the feed conveyor 4 and / or is from the two transverse directions 11 , 12 clamped.

The upper product guide 8 can be moved in the second transverse direction 12 - which runs perpendicular to the surface of the upper run of the feed conveyor 4 folded up into the slicing position - to adapt to the height H of the caliber K in this direction, which can be determined by a height sensor 19. Furthermore, at least one of the product guides 8, 9 can be designed to be pivotable about one of its deflection rollers 8a, 8b, 9a, 9b in order to be able to change the direction of the strand of your conveyor belt resting on the caliber K to a limited extent.

The slices S, which are positioned at an angle in space during separation, fall according to the inclination of the feed unit 20 and the cutting plane 3" - see Figure 2 - on a discharge unit 17 that begins below the cutting frame 5 and runs in the direction of travel 10*, which in this case consists of several discharge conveyors 17a, b, c arranged one behind the other in the direction of travel 10* with their upper strands approximately aligned, one of which also serves as a weighing unit can be trained.

Below the feed unit 20 there is also an approximately horizontally running residue conveyor 21, which begins with its front end below the cutting frame 5 and immediately below and / or behind the discharge unit 17 and with its upper run, residues falling onto it from there in the opposite direction Flow direction 10* transported backwards.

For this purpose, at least the first discharge conveyor 17a in the direction of flow 10* can be driven with its upper run counter to the direction of flow 10*, so that a remaining piece KR falling onto it, for example, can be transported to the rear and falls onto the remaining piece conveyor 21 located lower down.

After separation, the slices S either fall directly onto these conveyors 17a - c, as in Figure 1b shown, or, as in Figure 2 shown, onto a packaging element V resting thereon, such as a carrier cardboard box or a flat plastic tray.

When cutting a disk S, the cutting edge 3a runs at a short distance from the Figure 3a drawn cutting gap 100, along the front surface of the cutting glasses 5 facing the knife 3, and thereby covers the entire cross-section of the respective glasses opening 6, from which the product caliber K - which for reasons of clarity is shown in Figure 3a not shown - protrudes.

The cutting edge 3a penetrates in the immersion direction 25 from the upper edge 5b of the front surface 5.1 of the cutting glasses 5 further and further along the front surface 5.1, viewed in the axial direction 10 according to Figures 4a to c the immersion direction 25 is defined as a radial beam from the knife axis 3 'at a right angle to the upper edge 5b of the cutting glasses 5

The peripheral edge of the spectacle opening 6 on the front side of the cutting spectacles 5 acts as a counter edge 5a for the cutting edge 3a, at least over part of the circumference of the spectacle opening 6.

The cutting gap 100 is necessary above all so that the knife 3 with its cutting edge 3a does not slide along the front surface of the cutting glasses 5 with each cut, since this would, on the one hand, cause the cutting edge 3a to become blunt very quickly and, on the other hand, would damage the front surface and in particular the counter edge 5a of the cutting glasses 5.

On the other hand, a cutting gap 100 that is too large prevents a sufficient effect of the counter edge 5a on the cutting edge 3a and worsens the cutting result.

Therefore, the cutting gap 100 is often controlled by readjusting the - preferably rotating - knife 3 according to Figure 3a in the approach direction 10a, which is parallel to the knife axis 3', is brought ever closer to the cutting glasses 5 by means of an adjusting device 23 - without there being a product caliber for cutting therein - until the knife 3 contacts the front surface of the cutting glasses 5, which is recognizable to the control 1* of the machine in that an automatically monitored parameter in this regard, for example the idle torque ML of the knife 3 or of the knife motor 22 driving it, increases.

As in Figure 5a As shown, the idle torque ML, which always fluctuates slightly even during one revolution of the knife 3, will increase from an average idle torque ØML before contact. If this is a relative increase by a 1st torque difference MD1 or an absolute increase above an absolutely defined torque threshold MS, this is evaluated by the control 1* as contact between the knife 3 and the cutting glasses 5 and the approach movement in the approach direction 10a is stopped.

The blade is then rotated a further fixed number of times and it is checked whether there is a sharp drop of more than a second torque difference MD2 from the maximum idle torque MLmax reached. If this is not the case, the increase was not caused by a particle, such as a meat fiber, that got caught between blade 3 and cutting frame 5 and was then thrown away again, but by direct contact between blade 3 and cutting frame 5.

Then the knife 3 is moved back axially in the spacing direction 10b by a distance that corresponds to the desired cutting gap 100.

From this contacting axial position, the control 1* causes the knife 3 to move back in the spacing direction 10b by the distance of the desired cutting gap 100.

As long as the knife plane 3" defined by the cutting edge 3a lies parallel to the front surface 5.1 of the cutting glasses 5, the cutting gap 100 thus set is uniformly maintained during the entire cutting movement of the knife 3 - in which there is an overlap of the knife 3 and the cutting glasses 5 when viewed in the axial direction 10.

However, if these two surfaces are not parallel to each other - i.e. if they are at an angle to each other by more than a tolerance angle to be determined - then a cutting gap 100 that remains constant throughout the cutting movement cannot be set, and a warning signal should be given by the control, initially by the operator The parallelism of the cutting plane 3" to the front surface 5.1 of the cutting glasses 5 is again established.

As a rule, the course of the knife axis 3' is not adjustable and the knife 3 is flat in that its cutting edge 3a defines a knife plane 3".

This means that only the front surface 5.1 of the cutting glasses 5 can be adjusted in position. If there is a lack of parallelism, this front surface 5.1 is at a differential angle β about an inclination axis 26 at an angle to the knife plane 3", which should be eliminated or at least minimized.

If the first transverse direction 11, the width direction of the slicer 1 , is the inclination axis 26a - i.e. is transverse to the immersion direction 25 of the knife 3 - and the upper edge 5b of the front surface adjacent to the cutting axis 3' 5.1 is further away from the cutting plane 3" than the lower edge 5c facing away from the cutting axis 3', the situation arises according to Figure 3b :
When the knife 3 approaches axially in the approach direction 10a, the rapidly rotating knife 3 will first reach the front surface 5.1 with its cutting edge 3a at or near its lower edge 5c - as in Figure 4b shown - and with further pressure by means of the adjustment device 23, the monitored idle torque ML increases, but due to the flexibility of the knife 3, significantly more slowly than when the knife 3 is placed on the front surface 5.1 simultaneously over their entire overlap area, which can make it difficult for an evaluation unit of the control 1* to detect the contact between the knife and the cutting glasses 5 in good time.

However, according to Figure 3c the inclination axis 26b the second transverse direction 12, - i.e. parallel to the immersion direction 25 - so when the rotating knife 3 approaches axially in the approach direction 10a, the knife 3 reaches the front side 5.1 of the cutting glasses 5 for the first time with its cutting edge 3a either at the left or at the right end of the cutting glasses 5, measured transversely to the immersion direction 25, i.e. in the 1st transverse direction 11, thus shortly after the in Figure 4a shown rotation position or shortly before the Figure 4b shown rotational position, which in both cases leads to the fact that during the sweep of the spectacle opening 6 or the several spectacle openings 6a, b by the cutting edge 3a, the cutting gap 100 set from the contact would be too large.

In the Figures 4a to 4d the cutting segment of the cutting unit 7 is shown in relation to a specific knife 3 used therein.

The cutting edge 3a penetrates according to Figure 4a viewed in the axial direction 10 for the first time in the cross section of a first of the spectacle openings 6a, 6b, here the spectacle opening 6b, a with a rotational position of the knife 3 in which a radial reference line 27 - here the radial beam from the knife axis 3' to the beginning of the cutting edge 3a, at which this has the smallest distance to the knife axis 3' - is at an entry angle α1 from the immersion direction 25 - the perpendicular to the upper edge 5b of the cutting glasses 5 through the knife axis 3'.

With further rotation, the cutting edge 3a initially reaches Figure 4b the lower edge 5c of the cutting glasses 5 and a little later the cutting edge 3a emerges from the cross section of the first glasses opening 6b in the direction of rotation of the knife, whereby this order can also be reversed depending on the size ratios and design of the cross section of the glasses openings 6a, b and of the knife 3.

At the latest shortly before reaching the turning position according to Figure 4c the peripheral edge of this spectacle opening 6b acts as a counter edge 5a to the cutting edge 3a, as in Figure 3a and Figure 4d shown.

As in Figure 4d As shown, the cutting edge 3a then emerges from the cross section of the last spectacle opening 6a in the direction of rotation of the knife 3 at an exit angle α2 upon further rotation, and here too, before reaching this rotational position, the peripheral edge of this spectacle opening 6a acts as a counter edge 5a to the cutting edge 3a.

The intermediate angle between α1 and α2 therefore represents the cutting segment α2-α1.

With reference to the cutting segment α2-α1, the following statements can be derived from the contacting, rotating but axially stopped knife 3:
If the idle torque ML increases within one revolution of the knife 3 before the entry angle α1 is reached, the upper edge 5b of the cutting frame 5 is closer to the cutting plane 3" than the lower edge 5c, with an inclination about the inclination axis 26a.

If the idle torque ML increases within the cutting segment α2-α1 within the first half, in particular the first third, or only in the second half, in particular the third third, of the cutting segment α2-α1, there is an inclination of the front surface 5.1 second inclination axis 26b and the knife 3 first contacts the right or left end of the cutting glasses 5.

If the idle torque ML increases approximately in the middle of the cutting segment α2-α1, the front surface 5.1 is again inclined about the first inclination axis 26a, but the lower edge 5c is then closer to the cutting plane 3" than the upper edge 5b.

These automatically determined statements can be provided to the operator for the readjustment of the cutting glasses 5 by the control 1*, e.g. via the display of the control 1*.

Of course, the front surface 5.1 can also be inclined about an inclination axis that runs obliquely to the two transverse directions 11 and 12. In this case, several of the above statements apply cumulatively.

The Figures 4a to 4d show further that - viewed in the axial direction 10 - the contour of the peripheral edge of the knife is shaped and dimensioned in such a way and the axis of rotation 3' of the knife 3 is arranged relative to the cutting glasses 5 in such a way, in particular at such a distance from the cutting glasses 5, that of a full 360° revolution of the knife 3, this is between 1/4 and 1/3 of a full revolution without overlap with the cutting glasses 5

Figure 5b shows the possible range of fluctuation δv of the rotational speed v of the idling knife 3 during one complete revolution, so that the actual rotational speed Ist-v mostly oscillates around the desired target rotational speed Soll-v and the knife motor 22 is controlled depending on this during speed control.

If the relative fluctuations δv are greater than a specified tolerance difference δvD, the current supply is increased during speed control if the rotational speed has dropped to an unacceptable level, and reduced in the opposite case, until the rotational speed is again within the permissible range.

If the absolute deviations from the target rotational speed Soll-v are greater than a specified tolerance deviation Tol-δv, the current supply is increased during speed control if the rotational speed has dropped to an unacceptable level, and reduced in the opposite case, in each case until the rotational speed is again within the permissible range.

LIST OF REFERENCE SYMBOLS

1

Slicing machine, slicer

1*

steering

2

Base frame

3

Knife

3'

Knife axis

3"

Knife plane, cutting plane

3a

Cutting edge

4

Feed conveyor, feed belt

4'

Swivel axis

5

Caliber guide, cutting glasses

5.1

Front surface

5a

Counter edge

6, 6a - d

Glasses opening

7

cutting unit

8th

upper product guide

8a, b

Deflection pulley

9

lower product guide

9a, b

Deflection pulley

10

axial direction, feed direction

10a

Approach direction

10b

Spacing direction

11

first cross direction (width slicer)

12

second transverse direction (height-direction caliber)

13

Gripper unit, gripper carriage

14.14a - d

Grabber

15

survey

16

Grab claw

17

Discharge unit

17a, b, c

Portioning belt, conveyor

18

Gripper guidance

19

Altitude sensor

20

Feed unit

21

Remnant conveyor

22

Knife motor

23

Adjustment device

24

Torque sensor

25

Immersion direction

26a, b

Inclination axis

100

Cutting gap

α1

Entrance angle

α2

exit angle

α2-α1

Cutting segment

β

Difference angle

K

Caliber, product caliber

MD1

first moment difference

MD2

second moment difference

MLmax

maximum reached idle torque

MS

Torque threshold

ØML

average idle torque

S

disc

v

Packaging element

v

Orbital speed

δv

Range of fluctuation, change

δvD

Tolerance difference of the rotational speed

Tol-δv

Tolerance deviation of the orbital speed

Claims (15)

1. Method for automatically setting the cutting gap (100) of a cutting machine (1) for cutting strand-like product gauges (K) from a food in slices (S), which comprises

   - a blade (3) which can be driven in rotation about a blade axis (3') by means of a blade motor (22) and which comprises a cutting edge (3a) on the periphery that defines a blade plane (3"),

   - a gauge guide (5) having a mating edge (5a) for interaction with the cutting edge (3a),

   by the method steps of

   a) approaching the idle-running, rotating blade (3) along the blade axis (3') in an approach direction (10a) until it touches the gauge guide (5),

   b) stopping the approach movement of the blade (3),

   c) moving the blade (3) back in the spacing direction (10b) by a distance corresponding to the desired size of the cutting gap (100), measured in the direction of the blade axis (3'),

   - in or before step a)
   the idle-running torque (ML) of the blade motor (22) or of the blade (3) being measured, characterised in that

   - in step b)
   the approach movement of the blade (3) is stopped

   - as soon as an increase in the idle-running torque (ML) by at least a fixed first torque difference (MD1) is determined,

   - or as soon as it is determined that a fixed absolute torque threshold value (MS) is reached,

   in step b), after stopping of the approach movement,

   - a plurality of blade revolutions being performed with unchanged power supply to the blade motor (22),

   - a check being made as to whether, during this time, the idle-running torque (ML) does not drop by more than a fixed second torque difference (MD2),

   - the return movement according to step c) being started only in the positive case.
2. Method according to claim 1,
   characterised in that

   - the power supply to the blade motor (22) in idle running is controlled depending on occurring changes (δv) of the revolution speed (v) of the blade (3) during a complete blade revolution, in that

   - in the event of a fixed tolerance difference (δvD) between the lowest and the highest occurring revolution speed during a full blade revolution being exceeded, the power supply to the blade motor (22) is increased if there has been an inadmissibly large drop in the revolution speed, and in the reverse case is reduced, in each case until the revolution speed is in the allowable range again.
3. Method according to claim 1,
   characterised in that

   - the power supply to the blade motor (22) in idle running is controlled depending on occurring deviations (δv) of the actual revolution speed (Ist-v) from a target revolution speed (Soll-v) during a complete blade revolution, in that

   - in the event of a fixed tolerance deviation (Tol-δv) being exceeded, the power supply to the blade motor (22) is increased if there has been an inadmissibly large drop in the revolution speed, and in the reverse case is reduced, in each case until the revolution speed is in the allowable range again.
4. Method according to any of the preceding claims,
   characterised in that
   in step b), after stopping of the approach movement,

   - at least 3, preferably at least 5, preferably at least 10, blade revolutions are performed with unchanged power supply to the blade motor (22).
5. Method according to any of the preceding claims,
   characterised in that
   the approach movement is performed at an approach rate of at most 0.1 mm per blade revolution, preferably at most 0.08 mm per blade revolution, preferably at an approach rate of between 0.1 mm and 0.01 mm, preferably between 0.08 mm and 0.03 mm, per blade revolution.
6. Method according to any of the preceding claims,
   characterised in that
   the automatic setting is performed

   - after each movement of the gauge guide (5),
   and/or

   - before cutting each new gauge (K).
7. Method according to any of the preceding claims,
   characterised in that
   in step a)

   - a check is automatically made as to whether, in each case within a revolution of the blade (3), the idle-running torque (ML) increases significantly in each case immediately before the entry angle (α1) is reached,

   - in the positive case, a warning signal is output in order that the parallel position of the front surface (5.1) of the gauge guide (5) relative to the blade plane (3") is checked,

   - in particular, the operator is informed that the top edge (5b) of the cutting glasses (5) is located closer to the cutting plane (3") than the lower edge (5c).
8. Method according to any of the preceding claims,
   characterised in that
   in step a)

   - a check is automatically made as to whether, in each case within a revolution of the blade (3), the idle-running torque (ML) increases significantly approximately in the central region of the cutting segment (α2- α1),

   - in the positive case, a warning signal is output in order that the parallel position of the front surface (5.1) of the gauge guide (5) relative to the blade plane (3") is checked,

   - in particular, the operator is informed that the lower edge (5c) of the cutting glasses (5) is located closer to the cutting plane (3") than the top edge (5b).
9. Method according to any of the preceding claims,
   characterised in that
   in step a)

   - a check is automatically made as to whether, in each case within a revolution of the blade (3), the idle-running torque (ML) increases significantly, in each case within the first half, in particular the first third, or only in the second half, in particular the third third, of the cutting segment (α2- α1),

   - in the positive case, a warning signal is output in order that the parallel position of the front surface (5.1) of the gauge guide (5) relative to the blade plane (3") is checked,

   - in particular, the user is informed that an oblique position of the front surface (5.1) about a tilt axis (26b) positioned in parallel with the plunge direction (25) is present.
10. Method according to any of the preceding claims,
    characterised in that
    the method is carried out at a rotational speed of the blade of 50 rpm to 500 rpm, preferably of 50 rpm to 150 rpm.
11. Cutting machine (1) comprising

    - a base frame (2),

    - a blade (3) which can be driven in rotation about a blade axis (3') by means of a blade motor (22) and which comprises a cutting edge (3a),

    - a mating edge (5a), in particular formed on a front gauge guide (5) for the product gauge (K) to be cut,

    - an adjustment device (23) for adjusting the blade (3), relative to the mating edge (5a), in the direction of the blade axis (3'),

    - a controller (1*) for actuating the adjustment device (23) and the blade motor (22),
    characterised in that

    - a torque sensor (24) for measuring the torque output by the blade motor (22) or the torque with which the blade (3) rotates is provided,

    - the controller (1 *) is designed to carry out the method according to any of the preceding claims.
12. Cutting machine according to claim 11,
    characterised in that

    - the gauge guide (5) is movably fastened to the base frame (2) of the machine (1),

    - in particular so as to be movable transversely to the axial direction (10),
    and/or

    - in particular so as to be movable with respect to the angular position of its front surface (5.1) relative to the blade plane (3").
13. Cutting machine according to either claim 11 or claim 12,
    characterised in that

    - a rotation angle sensor for determining the rotational position of the blade (3) is provided,

    - the torque sensor (24) and the controller (1*) are designed to determine the rotation angle of the blade (3) within one revolution, in which a significant increase in the idle-running torque (ML) occurs.
14. Cutting machine according to any of claims 11 to 13,
    characterised in that
    the largest radius of the blade is between 300 mm and 600 mm.
15. Cutting machine according to any of claims 11 to 14,
    characterised in that,
    viewed in the axial direction (10), the contour of the peripheral edge of the blade (3) is shaped and dimensioned in such a way, and the axis of rotation (3') of the blade (3) is arranged relative to the cutting glasses (5) in such a way, in particular at such a distance from the cutting glasses (5), that, of a full 360° revolution of the blade (3) this is between 1/4 and 1/3 of a full revolution without overlap with the cutting glasses (5).

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