EP1818101A2 - Roll mill - Google Patents

Abstract

The rolling mill has at least two rolls (1,2,3) that are rotatably mounted about their longitudinal axes. The press device is used for pressing at least one roll (2) with the other roll (1,3) which is carried out by a mechanical pneumatic press device (4,5) comprising of a force converter (6) and a pneumatic drive (7). The rotational axis of the first roll (2) being mounted in a fixed manner and the rotational axis of the second roll (1,3) being displaceably mounted in addition to at least one press device.

Description

The invention relates to a rolling mill, in particular a three-roll mill, for the comminution and homogenization of viscous masses, in particular for dispersing and uniform distribution in a binder of suspended solid particles. Such a rolling mill has at least two rollers mounted rotatably about their longitudinal axes, wherein the axis of rotation of the first roller is mounted in a stationary manner and the axis of rotation of a second roller is movably mounted. With at least one pressing device is a pressing of at least one roller against the other.

The invention has for its object to provide a rolling mill of the aforementioned basic type, which allows an improvement in product quality and thereby avoids product inhomogeneities by better grinding.

The avoidance of product inhomogeneities by z. B. undispersed oversize grain is achieved by a rolling mill with the features of claim 1. The back roll or take-off roll intended for product removal has a shorter axial process length than the middle roll and is axially disposed relative to the middle roll such that the ends of the process length of the center roll over both ends of the process length of the back roll and take-off roll, respectively protrude axially. This has the advantage that during operation of the rolling mill unrug or inadequately rubbed, i. does not get too coarse product from the middle roll on the rear roller or take-off roll. This measure therefore allows an improvement in product quality, i. achieve a more consistent product fineness, undefined edge effects are avoided.

The roll surfaces or process surfaces are preferably formed from a metal-free ceramic material, wherein the rolls preferably have a ceramic cylinder fitted onto a hollow metal cylinder. This will remove any metallic contamination of the product during its comminution due to roll abrasion locked out. This is especially important in the processing of pastes for applications in electronics and for the manufacture of insulator bodies based on fine ceramics.

In a particularly advantageous embodiment of the present invention, the rolling mill according to the invention is a so-called "three-roll mill" with three rollers lying parallel to one another. The axis of rotation of the middle roller is fixedly mounted, while the axis of rotation of the front roller or feed roller and the axis of rotation of the rear roller or take-off roller are movably mounted. For this purpose, it has a front mechanical-pneumatic pressing device for pressing the front roller against the central roller and a rear mechanical-pneumatic pressing device for pressing the rear roller against the central roller. Thus, two nips are available. By adjusting the gap distance, the differential speed and the pressure in the respective gap, the operating conditions can thus be set independently for the two nips.

In a further solution of the problem, in particular the subtask of an improved cooling effect are in the rolling mill or three-rolling mill a first plane, which is defined by the axis of rotation of the front roller and feed roller and by the axis of rotation of the middle roller, and a second plane which by the axis of rotation of the central roller and defined by the axis of rotation of the rear roller or acceptance roller is inclined at an angle between about 10 ° and a maximum of 90 ° to each other, wherein in particular the first plane is horizontal, while the second plane extends obliquely upward (in Side view L-shaped arrangement of the rollers). Preferably, the angle is 30 ° to 60 ° and more preferably about 45 °. This ensures that the present as a viscous mass product with the dispersed solid particles (eg pigments) during its passage through the rolling mill is cooled longer than in an arrangement in which the axes of rotation of the front, the middle and the rear roller in one Lie flat.

Such an arrangement results in a longer residence time of the product on the cool surface of the rolls.

Conveniently, the rollers are cooled from the inside. This is e.g. important in the processing of organic pigments, especially some yellow pigments.

Preferably, both the front roller and the rear roller are pressed by means of a mechanical-pneumatic pressing device against the middle roller. This allows adjustment of the front and rear nip. Preferably, the mechanical-pneumatic pressing device has a control for gap adjustment. Since the force transducer, as explained above, allows a "force transmission" and a "path reduction", the relatively weak force of a pneumatic for the purpose of roll pressing can be multiplied and at the same time greatly increased by the pneumatics accuracy for the gap adjustment.

Conveniently, a scraper is applied to the take-off roll, over which the comminuted homogenized mass is stripped off, the scraper preferably also consisting of a metal-free material, in particular of a ceramic material or of a polymer material. This also eliminates any metallic contamination of the product during its stripping from the pickup roller due to wiper abrasion.

Preferably, at least the catchment area of the rolling mill is covered by a top. This prevents unwanted contaminants from entering the product from the factory floor and, vice versa, prevents unwanted volatile product components from escaping into the factory floor. One thus improves on the one hand the "product hygiene" and on the other hand the "workplace hygiene".

Preferably, the space under the hood is connected to a gas vent. Thereby, e.g. volatile substances contained in the solvent of the product are kept away from the air of a factory floor.

Fig. 1

eine schematische Seitenansicht eines ersten Ausführungsbeispiels des erfindungsgemässen Walzwerks ist;

Fig. 2

eine Draufsicht auf die Walzen des ersten Ausführungsbeispiels in Fig. 1 ist;

Fig. 3

eine der Fig. 1 entsprechende schematische Seitenansicht eines zweiten Ausführungsbeispiels ist; und

Fig. 4

eine Draufsicht auf die Walzen des zweiten Ausführungsbeispiels in Fig. 3 ist.

Further advantages, features and possible applications of the invention will become apparent from the following description of non-limiting embodiments of the invention, wherein:

Fig. 1

a schematic side view of a first embodiment of the inventive rolling mill;

Fig. 2

is a plan view of the rollers of the first embodiment in Fig. 1;

Fig. 3

one of the Figure 1 is a schematic side view of a second embodiment; and

Fig. 4

is a plan view of the rollers of the second embodiment in Fig. 3.

A first embodiment of the rolling mill according to the invention is shown in FIG. 1 and in FIG. 2. The three-roll mill shown here contains three rollers 1, 2, 3, which are aligned parallel to each other and all arranged in a plane E. In other words, the rotational axis A1 of the front roller 1, the rotational axis A2 of the middle roller 2 and the rotational axis A3 of the rear roller 3 are parallel to each other (see Fig. 2) and are all in one and the same plane E. In the operating position, the Front roller 1 and the rear roller 3 are pressed by means of a front pressing device 4 and by means of a rear pressing device 5 respectively against the central roller 2, whose axis of rotation A2 is mounted stationary. The front roller 1 and the rear roller 3 are movably supported, i. their axes of rotation A1 and A3 can be pivoted about a pivot axis D3. The lateral surfaces of the rollers 1, 2, 3 each represent the roller process surface S1, S2, S3, which come into contact with the product to be processed. Between the process surface S1 of the front roller 1 and the process surface S2 of the middle roller 2, a nip is formed during operation by the product passing between the rollers 1 and 2 pressed against each other. Likewise, a nip is formed between the process surface S3 of the rear roller 3 and the process surface S2 of the middle roller 2 in operation by the product passing between the rollers 2 and 3 pressed against each other.

The front pressing device 4 and the rear pressing device 5 each have a force converter 6 and a pneumatic drive 7. In the first embodiment shown in Fig. 1, the force transducer is a toggle lever 6, which consists of a first lever 6A and a second lever 6B, while the pneumatic actuator 7 is constituted by a pneumatic cylinder 7A and a pneumatic piston 7B. The power flow of the pressing devices 4 and 5 is based on the pneumatic piston 7B mounted in the pneumatic cylinder 7A, which is articulated via a piston rod to the first lever 6A on a hinge axis D1. The first lever 6A is articulated to a second hinge axis D2 on the second lever 6B, which in turn is articulated to a pivot axis D3 and each forms a pivotable suspension and mounting of the front roller 1 and the rear roller 3.

Depending on the dimensioning and orientation of the levers 6A and 6B, the toggle lever 6A, 6B serving as force transducer 6 and roller suspension effects an increase in the pneumatic force of the pneumatic drive 7 by a factor of about 20 to 50, this increased force being used for roller pressing. As a result, a sufficiently strong roller pressing is also possible with a pneumatic drive 7. On the other hand, this force transducer 6 causes a reduction of the stroke traveled by the pneumatic drive 7 by a factor of about 1/50 to 1/20, using this reduced stroke for gap adjustment.

The rollers 1, 2 and 3 are driven by the motor M by gears (not shown). The roller block 1, 2, 3 and the engine block M are surrounded by a housing G.

Fig. 2 is a plan view of the rollers 1, 2, 3 of the first embodiment of the rolling mill according to the invention shown in Fig. 1. It can be seen that the front roll or feed roll 1 and the middle roll 2 both have the same process length L1. = L2, while the rear roll or take-off roll 3 has a significantly shorter process length L3 <L2 in order to avoid undefined edge effects. The rear roller 3 is arranged axially with respect to the middle roller 2 such that the ends of the process length L2 of the middle roller 2 project axially beyond the ends of the process length L3 of the rear roller 3 on both sides. This ensures that unrestricted or insufficiently rubbed product from the middle roll 2 does not reach the rear roll 3 during operation of the three-roll mill, whereby a significant improvement in product quality can be achieved.

A second embodiment of the rolling mill according to the invention is shown in FIG. 3 and in FIG. 4.

All of the elements of the second embodiment shown in FIGS. 3 and 4, which are identical or correspond to the elements of the first embodiment shown in FIG. 1 and FIG. 2, bear the reference numerals of the corresponding element from FIG 1 or Fig. 2. The explanation of the function of these elements of the second embodiment will not be repeated here. In addition, the front pressing device 4 'and the rear pressing device 5' with their respective force transducer 6 'and pneumatic drive 7' are indicated only schematically.

The other reference numerals in Fig. 3 and in Fig. 4, which show different from the first embodiment elements of the second embodiment, have no stroke. Their function and meaning are explained below.

The essential difference between the first embodiment (Fig. 1 and Fig. 2) and the second embodiment (Fig. 3 and Fig. 4) is that the three-roll mill shown here comprises three rollers 1 ', 2', 3 'which Although they are aligned parallel to each other, but not all are arranged in one and the same plane. Rather, the axis of rotation A1 'of the front roller 1' and the axis of rotation A2 'of the central roller 2' are arranged in a first plane E1, while the axis of rotation A3 'of the rear roller 3' and the axis of rotation A2 'of the central roller 2' in one second plane E2 are arranged, which forms an angle of about 45 ° to the first plane E1. This arrangement of the three rollers 1 ', 2', 3 'allows the present as a viscous mass product with the solid particles distributed in it (eg pigments) during its passage through the rolling mill longer and thus can be cooled more than in an arrangement, in which the axes of rotation of the front, the middle and the rear roller lie in one plane.

4 is a plan view of the rollers 1 ', 2', 3 'of the second embodiment of the rolling mill according to the invention shown in FIG. Again, the front roller or feed roller 1 'and the middle roller 2' both have the same process length L1 ' = L2 ', while the rear roller or take-off roller 3' has a significantly shorter process length L3 '<L2'. The rear roller 3 'is also axially arranged with respect to the middle roller 2' such that the ends of the process length L2 'of the middle roller 2' axially protrude beyond the ends of the process length L3 'of the rear roller 3' on both sides. As already explained, this ensures that in the operation of the three-roll mill no unrestrained or only insufficiently rubbed product from the middle roll 2 'reaches the rear roll 3', whereby the product quality is improved.

The path traveled by the product as it passes through the rolling mill according to the second embodiment is increased by the two additional circular arc lengths on the surfaces S2 'and S3' of the rollers 2 'and 3' of radius R, which are defined by the angle γ between level E1 and level E2, ie an additional path compared to the first embodiment (Fig. 1) by 2 x γ x R.

A hopper or trough 8 with landing wedges, which extend on both sides of the catchment area, is arranged above the area of the pull-in gap between the front roll 1 'and the middle roll 2'. This product trough increases with its addition to the usual wedge seals provided Aufsetzkeilen the tightness and thus ensures a lower lateral product loss.

A scraper 9 with a scraper blade is used to remove the product from the rear roller 3 '. The scraper 9 is equipped with an automatic knife adjustment, which is controlled by a PLC control.

In both the first and second embodiments, the roller surfaces S1, S2, S3, S1 ', S2', S3 'may be made of ceramic material. The scraper 9 shown in Fig. 3 may also be made of ceramic material or of polymer material. These or other metal-free materials for the roller process surfaces and the doctor blade are of particular interest for the processing of pastes for the electronics industry.

The ceramic rolls are rounded at the end of the roll process length.

The pneumatic drive 7 operates e.g. with pressures of up to 4 bar, which come by means of the force transducer 6 to the required line pressures in the nips. The force transducer 6 makes it possible to increase the pressing force acting on the rollers by the roller press devices 4, 5 by a factor of about 10 to about 80. Accordingly, by reducing the stroke provided by the pneumatic drive 7 by means of the force transducer, the accuracy of the gap adjustment is about the same Factor increased.

The rolls have a diameter of 300 mm and the rear roll 3, 3 'is shorter by about 4 mm to 5 mm than the middle roll 2, 2'. This ensures that the wiper 9 strips only rubbed product from the rear roller 3 '.

reference numeral

1, 1 '

front roller / feed roller

2, 2 '

Roller with fixed axis of rotation / medium roller

3, 3 '

rear roller / take-off roller

4, 4 '

, front pressing device

5, 5 '

rear pressing device

6, 6 '

power converter

6A, 6B

first lever, second lever

7A

pneumatic cylinder

7B

pneumatic piston

7, 7 '

pneumatic drive

8th

hopper

9

scraper

A1, A1 '

axis of rotation

A2, A2 '

axis of rotation

A3, A3 '

axis of rotation

D1, D1 '

joint axis

D2, D2 '

joint axis

D3, D3 '

swivel axis

E1, E1 '

first floor

E2, E2 '

second level

F, F '

Arrow / viewing direction for Fig. 2 and Fig.4

G, G '

casing

L1, L1 '

Rolling process length

L2, L2 '

Rolling process length

L3, L3 '

Rolling process length

M, M '

engine

S1, S1 '

Rolling process area

S2, S2 '

Rolling process area

S3, S3 '

Rolling process area

Claims (8)

Rolling mill for comminution and homogenization of viscous masses, in particular for dispersing and uniform distribution in a binder suspended solid particles, with at least two rotatable about their longitudinal axes rotatably mounted rollers (1, 2, 3), wherein the axis of rotation of a first roller (2) is mounted stationary and the axis of rotation of a second roller (1, 3) is moveably mounted, and with at least one pressing device (4, 5) for pressing at least one roller (1, 3) against the other roller (2), characterized in that the rear roller or roller respectively in that the take-off roll (3) intended for the product removal has a shorter axial process length (L3) than the process length (L2) of the middle roll (2) and is arranged axially relative to the middle roll (2) such that the ends of the process length (L2 ) of the middle roll (2) project axially beyond the ends of the process length (L3) of the rear roll or take-off roll (3) on both sides. Rolling mill according to claim 1, characterized in that the roll surfaces or process surfaces (S1, S2, S3) are formed from a metal-free ceramic material. Rolling mill according to claim 1 or 2, characterized in that it is designed as a three-roll mill and the rolls are arranged in side view L-shaped. Rolling mill according to one of claims 1 to 3, characterized in that the rollers (1, 2, 3) have a ceramic cylinder fitted onto a hollow metal cylinder. Rolling mill according to one of claims 1 to 4, characterized in that the rollers (1, 2, 3) are cooled from the inside. Rolling mill according to one of claims 1 to 5, characterized in that the pressing device (4, 5) is a mechanical-pneumatic pressing device. Rolling mill according to one of claims 1 to 6, characterized in that the pressing device (4, 5) has a control for gap adjustment. Rolling mill according to one of claims 1 to 7, characterized in that the rear roller (3) is 2 mm to 10 mm, preferably 3 mm to 6 mm shorter.

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