EP0582774A1 - Holding device for the upper blade of a machine for high speed longitudinal slitting of web material - Google Patents

Abstract

The invention relates to a holding device for the upper blade of a cutting device having two circular blades for longitudinally cutting webs of material, in particular webs of paper, using the shear-cutting system, by means of flying cutting in a reel cutting machine especially in a high-speed rewinding cutting machine having a lowering device (1), which is preferably switched on and off pneumatically and a blade head device (2), which is switched on and off pneumatically, characterised by a) a double-action piston-cylinder unit (21), which has a buffer pressure chamber (22) and an adjusting pressure chamber (43) in a pressure cylinder (37), for adjusting the blade (11b) of the blade head device (2) and b) a pressure medium supply device (5) which is suitable for generating and maintaining different pressures in the two pressure chambers (22, 43) during the adjusting condition of the blade of the blade head device (2). <IMAGE>

Description

The invention relates to an upper knife individual holder for a cutting device for longitudinal cutting of material webs, in particular paper webs, according to the scissor cutting system by flying cutting z. B. in a high speed rewinding cutting machine.

The scissor cutting system uses two circular knives, namely an upper and a lower knife. The upper knife is arranged in an upper knife head of a single upper knife holder. The lower knife has a cutting edge with relief, whereby the upper knife dips somewhat into the lower knife. When cutting on the fly, the paper web is straight through the cutting zone and separated in the contact area between the upper and lower knife. The upper knife is usually - as seen from the inlet side of the material web - slightly oblique to the lower knife; on the other hand, there is little play on the outlet side.

The lower knife shaft is driven. The upper knife head can be turned easily and is driven by the upper knife against the lower knife with a lead of about 5%.

For high-speed rewinding cutting machines with large working widths, high running speeds and a large number of cuts (rewinder), individual holders for the upper knives are known, which have a pneumatic switching mechanism for moving the upper knife vertically and horizontally in the direction of the lower knife, with which the engagement depth of the upper knife ( Lowering of the upper knife head) and the lateral upper knife pressure and the inclination (adjustment of the upper knife to the lower knife) can be adjusted.

It is known that, in particular in the case of scissor-type knife holders which are loaded with compressed air, high vibration loads or dynamic loads act on the cutting tools as a result of the high cutting speed and can impair their function, the service life of the knives and the quality of the cutting edges. In particular because of the special cutting geometry of the upper knives of this type, the cutting edges of the knives break out, which means that the knife life is too short and the cut quality is poor and the dust is large. The rapid wear of the knives requires frequent retooling and therefore long downtimes for the cutting machine.

To solve the problem z. For example, attempts have been made to provide larger damping masses on the upper knife holder, an anti-rotation device on the holder axis and better ball bearing conditions on the knife head. In addition, a ball guide bush was used to guide the bearing axis for the axial adjustment movement of the upper knife.

The service life of the knives essentially depends on the lateral contact pressure between the upper and lower knives during operation. For the vertical and axial adjustment movements z. B. a minimum pressure of 4 bar required, which is reduced to 3 bar during operation by a known method, whereby the wear should be reduced.

Although these known means result in improvements with regard to the life of the ball bearings and with regard to knife wear, if continuous lubrication is also provided for the sliding parts, it has nevertheless been found that the improvements are not sufficient; For a solution to the problem, it has therefore been proposed to additionally eliminate the causes of the vibrations in the machine concept by the entire cutting section of the cutting machine in a separate system with damping units is housed.

The upper knives wear out due to material removal in the area of the overlap. The reason for the material removal is a. also caused by the slip between the upper and lower knife. However, a slip between the upper and lower knives is desirable to create a regrinding process. If the contact pressure is set too high, the cutting tools will fail prematurely.

The object of the invention is to provide a pneumatically switched upper knife individual holder for, in particular, a high-speed rewinding cutting machine which, with simple means, guarantees a long service life of the knives with correspondingly large regrinding intervals, so that in particular flawless cutting edges with little cutting dust accumulation over a long workflow , d. H. especially with short downtimes due to knife changes, and higher output rates can be guaranteed at lower costs.

Fig. 1

schematisch eine Seitenansicht eines Obermesser-Einzelhalters;

Fig. 2

einen Längsschnitt durch den Obermesserkopf;

Fig. 3

ein Druck-/Kraft-Diagramm zur Erläuterung der Funktion der erfindungsgemäßen Anstelleinrichtung;

Fig. 4

ein weiteres Druck-/Kraft-Diagramm zur Erläuterung der Funktion der erfindungsgemäßen Anstelleinrichtung.

This object is solved by the features of claim 1. Advantageous developments of the invention are characterized in the subclaims. Based on the embodiment shown in the drawing, the invention is explained in more detail below. Show it:

Fig. 1

schematically a side view of a single upper knife holder;

Fig. 2

a longitudinal section through the upper cutter head;

Fig. 3

a pressure / force diagram for explaining the function of the adjusting device according to the invention;

Fig. 4

another pressure / force diagram to explain the function of the adjusting device according to the invention.

The upper knife individual holder according to the invention (hereinafter only called the knife holder) essentially consists of a lowering device 1 and a knife head device 2. The lowering device 1 is not part of the subject matter of the invention; it is constructed as usual and has z. B. a vertically aligned lowering piston rod 3 and a guided in the pressure chamber of a pressure housing 4 against a return spring, can be acted upon by a pressure medium lowering piston. The pressure chamber of the pressure housing 4 is supplied with pressure medium via a pressure medium supply device 5. On the pressure housing 4 is usually a holding block with z. B. a prismatic guide for holding and adjusting the knife holder on a cutter bar of a slitter (not shown).

The cutter head device 2 is located at the lower end of the lowering piston rod 3 on the knife side. It has a support shaft 7, which is horizontally movable in a double arrow direction 14 in an adjusting housing 6, the adjusting housing 6 being arranged fastened to the lowering piston rod 3.

On the end region of the support shaft 7 protruding from the adjusting housing 6 on the knife side, a hub 10, which has an annular groove 11 and is rotatable about an axis of rotation 36 passing through the support shaft 7, is supported via ball bearings 9. The hub-side annular groove wall 11a has a radially outer, conical oblique surface 11a, to which the upper knife 11b is arranged so that it can be replaced. Due to the oblique course of the surface 11a, a larger-area contact of the upper knife 11b with the hub 10 is achieved than in the case of a groove wall running perpendicular to the wheel shaft 7. The advantage of the larger contact surface for the upper knife 11b is a reduction in fretting corrosion, that is to say less abrasion between the hub 10 and the upper knife 11b.

Arranged on the wall 11c opposite the groove wall 11a is an elastic, annular rubber element 11d, the thickness of which is selected such that it adjoins the upper knife 11b.

The rubber element 11d, among other things, compensates for the lateral runout of the upper knife 11b, reduces fretting corrosion and dampens vibrations.

The guided in the storage room 13 of the adjusting housing 6 support shaft 7 is supported radially on z. B. two axially spaced support rings, z. B. Teflon rings 15. In the area between the support rings 15, a vertical threaded bore 16 is made in the wall of the adjusting housing 6, in which an externally accessible grub screw 17 is seated. The lower end region of the grub screw 17 engages freely in an axially parallel longitudinal groove 18 which is introduced into the lateral surface of the support shaft 7 such that the movement of the support shaft 7 in the double arrow direction 14 is not hindered. The task of the grub screw 17 is explained below.

The end of the support shaft 7 facing away from the hub 10 is connected to the front end of an adjusting piston rod 19, which extends through a hole 23 in the rear wall 20 of the adjusting housing 6 axially freely into the adjusting housing 6 and with its piston 8 in the pressure chamber of a pressure cylinder 37 double-acting piston cylinder device 21 is guided. The pressure cylinder 37 is axially sealed to the pressure medium above the hole 23 on the rear wall 20 of the adjusting housing 6 and has a buffer pressure space 22 and a setting pressure space 43.

An elastic coupling, which has an elastic buffer 25 between two coupling heads 26, 27 made of a rigid material, is preferably arranged on the end of the adjusting piston rod 19 protruding into the storage space 13 of the adjusting housing 6, the piston rod 19 on the rear coupling head 26 and the front coupling rod 19 Coupling head 27 a mounting pin 28 sit. The fastening pin 28 is detachably fastened in an axial blind hole 29 in the rear end region of the support shaft 7. The releasable fastening consists of an annular groove 30 provided in the fastening pin 28, into which a grub screw 31 engages, which is seated in a threaded wall hole 32 of the support shaft 7.

Axially aligned with the threaded bore 32, a bore 33 is made in the wall of the adjusting housing 6, so that the grub screw 31 is accessible from the outside with a tool.

The purpose of the elastic buffer 25 is an elastic coupling of the support shaft 7 to the adjusting piston rod 19, in particular with the aim of compensating for misalignments between the support shaft 7 and the piston rod 19 and thus preventing damage to the seals of the cylinder 37. The elastic coupling also serves to transmit the force generated in the pressure chamber 43 to the support shaft 7.

The rear wall 20 is expediently releasably attached to the housing side walls 35 of the adjusting housing 6 with screws 34 which are parallel to the axis. By loosening the grub screws 17.31, the support shaft 7 with the hub device can be pulled forward out of the adjusting housing 6. By loosening the screws 34, the rear wall 20 with the piston cylinder device 21 can also be removed from the adjusting housing 6.

With the pressure medium supply device 5, the pressure spaces 22, 43 of the piston-cylinder device 21 are also supplied with pressure medium, the buffer pressure space 22 being sealed off from the storage space 13 of the adjusting housing 6 so as to be pressure-tight. For this purpose, the bottom 38 of the pressure cylinder 37, which is adjacent to the rear wall 20, has a sealing ring which is mounted in an annular groove 39 on the rear wall and which lies against the piston rod 19, which freely passes through a passage 41 which is adapted to the diameter of the piston rod 19. The piston 8 is seated firmly at the free end of the piston rod 19 and is located in the region of the cylinder cover 42, the contact pressure space 43 being formed between the cylinder cover 42 and the piston 8. A connection bore 44 leads to the buffer pressure chamber 22 and a connection bore 45 leads to the setting pressure chamber 43, through which pressure medium can be directed from the pressure medium supply device 5 into the pressure chambers 22, 43 via a pressure medium line 46 or 47 (see FIG. 1).

The end face of the piston 8 opposite the cylinder cover 42 is chamfered (at 48) so that pressure medium can be applied to the piston rear side via the connection bore 45.

The function of the adjusting device according to the invention will be explained in more detail below with reference to FIGS. 3 and 4.

The contact pressure F _A is set according to the invention as the differential pressure between the pressure applied in the setting pressure chamber 43 and in the buffer pressure chamber 22 in order to ensure control of the driving force, which is independent of the frictional force F _R and the inertial force F _M , which counteract the driving force F _A.

wobei P₍₄₃₎ den im Anstellraum 43 herrschenden Druck und A₁ eine Konstante bezeichnet. Ein Druck-/Kraft-Verlauf auf der Grundlage der Formel (1) ist im Diagramm der Fig. 3 und 4 durch die Kennlinie K1 dargestellt.If the adjusting device is initially considered to be idealized without friction and mass, the contact pressure F _A generated by applying pressure in the contact pressure space 43 is determined as follows:

${\text{F}}_{\text{A}}{\text{= P}}_{\text{(43)}}\text{· A₁ (1),}$

where P ₍₄₃₎ denotes the pressure prevailing in the adjusting space 43 and A 1 denotes a constant. A pressure / force curve based on the formula (1) is shown in the diagram of FIGS. 3 and 4 by the characteristic curve K1.

Contrary to the assumed idealized conditions, in the real case, as mentioned above, a friction force F _R and a mass inertia force F _{M are} to be expected, which counteract the positioning force F _A and have to be overcome as follows to generate a positive positioning force F _A :

${\text{F}}_{\text{A}}{\text{+ F}}_{\text{R}}{\text{+ F}}_{\text{M}}{\text{= P}}_{\text{(43)}}\text{· A₁ (2).}$

Under these conditions, control of the contact pressure F _{A is} no longer possible in the required exact manner, since the friction force F _{R is present} as a non-constant static and sliding friction, the mass inertia force F _{M also being influenced} by the friction force F _R.

By introducing an additional force F, which can be precisely defined and is generated in the buffer pressure chamber 22, an exact control of the contact pressure can be achieved. A corresponding pressure / force curve is shown as a characteristic curve K2 in FIGS. 3 and 4. The force F is significantly greater than the friction force F _R and the inertia force F _M. The condition for the force F is:

${\text{F »F}}_{\text{R}}{\text{, F}}_{\text{M}}\text{(3).}$

In other words, it is necessary that the additional force F is substantially greater than the friction force F _R and the mass inertia force F _M. By applying the additional force F in the buffer pressure chamber 22, the friction force F _R and the inertia force F _{M can} be compensated so far that these forces can be neglected. When setting the characteristic curve K2 it should be noted that the slope of this characteristic curve is not chosen too steep to ensure that the required contact force F _{A can be set} over a large pressure range (see FIG. 3).

   Diesem Diagramm entspricht folgende Gleichung:

${\text{F₁ + F}}_{\text{R}}{\text{+ F}}_{\text{M}}{\text{+ F}}_{\text{A}}\text{= F₂ (4),}$

wobei für die Kräfte F_R, F_M, F₁ und F₂ folgende Gleichungen gelten:

${\text{F}}_{\text{R}}\text{= m · g · u (5)}$

${\text{F}}_{\text{M}}\text{= m · a (6)}$

$\text{F₁ = k₁ · x (7)}$

$\text{F₂ = k₂ · x (8),}$

wobei die in diesen Gleichungen genannten Konstanten wie folgt definiert sind:

k:

Federkonstante

u:

Reibfaktor

m:

Masse

x:

Weg

g:

Gravitationskonstante.

The derivation of the contact pressure F _A is to be clarified below, taking into account the additional force F by applying pressure in the buffer pressure chamber 22. The following diagram can be drawn up vectorially:

The following equation corresponds to this diagram:

${\text{F₁ + F}}_{\text{R}}{\text{+ F}}_{\text{M}}{\text{+ F}}_{\text{A}}\text{= F₂ (4),}$

the following equations apply to the forces F _R , F _M , F₁ and F₂:

${\text{F}}_{\text{R}}\text{= mg u (5)}$

${\text{F}}_{\text{M}}\text{= ma (6)}$

$\text{F₁ = k₁ · x (7)}$

$\text{F₂ = k₂ · x (8),}$

where the constants mentioned in these equations are defined as follows:

k:

Spring constant

u:

Friction factor

m:

Dimensions

x:

path

G:

Gravitational constant.

$\text{F₂ = k₂ · x₂ = A₂ · P₂ (10).}$

Da

${\text{F}}_{\text{R}}{\text{; F}}_{\text{M}}{\text{« F₁; F₂, F}}_{\text{R}}{\text{u. F}}_{\text{M}}\text{ (11)}$

gilt, lassen sich die Gleichungen (9) und (10) wie folgt verkürzen:

${\text{F₁ + F}}_{\text{A}}\text{= F₂ (12)}$

${\text{F}}_{\text{A}}\text{= F₂ - F₁ (13).}$

Wenn

da

den Kolbendurchmesser,

di

den Kolbenstangendurchmesser

P₁ und P₂

den Druck in den Kammern 22 und 43 bezeichnen, läßt sich die Formel (13) wie folgt darstellen:

${\text{F}}_{\text{A}}\text{= k · x₂-k₁·x₁ = A₂·P₂-A₁·P₁ (14)}$

${\text{F}}_{\text{A}}\text{= π₄ · (da² · P₂ - (da² - di²) · P₁) (15)}$

${\text{F}}_{\text{A}}\text{= π₄ · (da² (P₂ - P₁) + di² · P₁) (16).}$

The forces F₁ and F₂ are path-dependent, that is, dependent on the path x. Such a path dependency is unfavorable and is eliminated by the following agreement:

$\text{F₁ = k₁x₁ = A₁P₁ (9)}$

$\text{F₂ = k₂ · x₂ = A₂ · P₂ (10).}$

There

${\text{F}}_{\text{R}}{\text{; F}}_{\text{M}}{\text{«F₁; F₂, F}}_{\text{R}}{\text{u. F}}_{\text{M}}\text{(11)}$

equations (9) and (10) can be shortened as follows:

${\text{F₁ + F}}_{\text{A}}\text{= F₂ (12)}$

${\text{F}}_{\text{A}}\text{= F₂ - F₁ (13).}$

If

there

the piston diameter,

di

the piston rod diameter

P₁ and P₂

denoting the pressure in the chambers 22 and 43, the formula (13) can be represented as follows:

${\text{F}}_{\text{A}}\text{= kx₂-k₁x₁ = A₂P₂-A₁P₁ (14)}$

${\text{F}}_{\text{A}}\text{= π₄ · (da² · P₂ - (da² - di²) · P₁) (15)}$

${\text{F}}_{\text{A}}\text{= π₄ · (da² (P₂ - P₁) + di² · P₁) (16).}$

The piston diameter da and the piston rod diameter di are preferably to be selected such that the contact force F _{A can be set} over the largest possible pressure range.

Claims (18)

Upper knife individual holder for a cutting device with two circular knives for longitudinally cutting material webs, in particular paper webs according to the scissor cutting system by flying cutting in a reel cutting machine, in particular in a high-speed rewinding cutting machine with a preferably pneumatically switched lowering device (1) and a pneumatically switched knife head device ( 2),
marked by
a) a double-acting, a buffer pressure chamber (22) and a setting pressure chamber (43) in a pressure cylinder (37) having piston-cylinder unit (21) for setting the knife of the cutter head device (2) and b) a pressure medium supply device (5) suitable for generating and maintaining different pressures in the two pressure chambers (22, 43) while the knife is in the knife head device (2). Upper knife individual holder according to claim 1,
characterized,
that the cutter head device (2) has a hub (10) which is freely rotatably mounted on a support shaft (7) which can be pushed back and forth in a support housing (6) and on which the circular disc-shaped upper knife (11b) is seated, the hub (10) opposite end of the support shaft (7) is connected to a piston rod (19) of the piston-cylinder unit (21). Upper knife individual holder according to claim 2,
characterized,
that the piston-cylinder unit (21) is arranged on the rear wall (20) of the support housing (6), the piston rod (19) axially freely penetrating a hole (23) in the rear wall (20). Upper knife individual holder according to one or more of claims 1 to 3,
characterized,
that the buffer pressure chamber (22) of the piston-cylinder unit (21) is sealed in a pressure-medium-tight manner from the storage space (13) of the adjusting housing (6). Upper knife individual holder according to claim 4,
characterized,
that a bottom (38) adjacent to the rear wall (20) is provided in the pressure cylinder (37) of the piston-cylinder unit (21), which has a sealing ring (40) which is mounted in an annular groove (39) on the rear wall and which bears against the piston rod (19), which freely passes through a passage (41) in the base (38) adapted to the diameter of the piston rods (19). Upper knife individual holder according to one or more of claims 2 to 5,
characterized,
that the piston (8) of the piston-cylinder unit (21) is seated firmly at the free end of the piston rods (19) and is located in the region of the cylinder cover (42) of the piston-cylinder unit (21), with the cylinder cover (42) and the piston (8) the contact pressure chamber (43) is formed and the buffer pressure chamber (22) is located between the base (38) and the piston (8). Upper knife individual holder according to claim 6,
characterized,
that leads to the buffer pressure chamber (22) through the cylinder wall of the pressure cylinder (37) connecting hole (44) and to the setting pressure chamber (43) through the cylinder wall of the pressure cylinder (37) connecting hole (45) through which a pressure medium line (46 and 47 ) Pressure medium is passed from the pressure medium supply device into the pressure spaces (22, 43). Upper knife individual holder according to one or more of claims 1 to 7,
characterized,
that the adjusting housing (6) sits at the lower end of a lowering piston rod (3) of the lowering device (1). Upper knife individual holder according to one or more of claims 1 to 8,
characterized,
that the support shaft (7) on the end area protruding from the adjusting housing (6) carries via ball bearings (9) the hub (10) which has an annular groove (11) in which the circular disc of the upper knife is arranged so that it can be replaced. Upper knife individual holder according to claim 9,
characterized,
that the bearing shaft (7) guided in the storage space (13) of the adjusting housing (6) is supported radially on support rings (15) arranged at an axial distance from one another, for. B. from Teflon. Upper knife individual holder according to claim 10,
characterized,
that in the area between two support rings (15) a vertical threaded bore (16) is made in the wall of the adjusting housing (6), in which one is accessible from the outside Grub screw (17) is seated, the lower end region of which engages freely in an axially parallel longitudinal groove (18) which is introduced into the lateral surface of the support shaft (7) in such a way that the movement of the support shaft (7) in the double arrow direction (14) is not impeded. Upper knife individual holder according to one or more of claims 9 to 11,
characterized,
that the end of the support shaft (7) facing away from the hub (10) is connected to the front end of the coupling rod (19) via an elastic coupling (24). Upper knife individual holder according to claim 12,
characterized,
that the elastic coupling (24) has an elastic buffer (25) between two coupling heads (26, 27) made of a rigid material, the piston rod (19) on the rear coupling head (26) and a fastening pin (28) on the front coupling head (27) ) to sit. Upper knife individual holder according to claim 13,
characterized,
that the fastening pin (28) is detachably fastened in an axial blind bore (29) in the rear end region of the support shaft (7). Upper knife individual holder according to claim 14,
characterized,
that for the releasable fastening in the fastening pin (28) an annular groove (30) is provided, into which a grub screw (31) engages, which sits in a wall threaded bore (32) of the support shaft (7), being axially aligned with the threaded bore (32) in the wall of the adjusting housing (6) is drilled (33) so that the grub screw (31) is accessible from the outside with a tool. Upper knife individual holder according to one or more of claims 2 to 15,
characterized,
that the rear wall (20) of the support housing (6) is detachably fastened to the housing side walls (35) of the adjusting housing (6) by means of screws (34) arranged parallel to the axis. Upper knife individual holder according to one or more of claims 2 to 16,
characterized,
that the hub (10) has an inclined upper knife-carrying surface (11a). Upper knife individual holder according to one of claims 2 to 17,
characterized,
that the upper knife (11b) is braced against the hub (10) by means of an elastic rubber element (11g).

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