GB2471755A

GB2471755A - Apparatus on a flat card or roller card for setting the working spacing between the cylinder and at least one neighbouring roller

Info

Publication number: GB2471755A
Application number: GB1011158A
Authority: GB
Inventors: Britta Jacobs; Robert Pischel
Original assignee: Truetzschler GmbH and Co KG
Current assignee: Truetzschler GmbH and Co KG
Priority date: 2009-07-06
Filing date: 2010-07-02
Publication date: 2011-01-12
Anticipated expiration: 2030-07-02
Also published as: CN101942714A; ITMI20101216A1; GB2471755B; GB201011158D0; IT1401104B1; CH701398B1; DE102009031978A1; CN101942714B; CH701398A2

Abstract

Apparatus on a flat card or roller card for setting the working spacing between a clothed cylinder (4, figure 2) and at least one clothed neighbouring roller (5), for example doffer and/or licker-in, comprises an adjustment device 28 operable by supplying and/or actively dissipating thermal energy. The device may move a doffer, licker-in or the main cylinder to compensate for changes in the working spacing caused by thermal or centrifugal effects. The adjustment device may comprise a peltier effect device 29 attached to an aluminium low mass tube to heat or cool the tube to effect the compensation. Alternatively a high volumetric expansion coefficient fluid (44, figure 5) may be heated or cooled using a peltier device (29) to cause activation of a spring biased piston (42). In an emergency a valve (60, figure 11) may be opened to release fluid. Alternatively, the cooling effect of compressed air may be used to cool the adjusting device. A closed loop control circuit may be used to regulate the energy supply of the peltier device.

Description

Apparatus on a flat card or roller card for setting the working spacing between the cylinder and at least one neighbouring roller The invention relates to an apparatus on a flat card or roller card for setting the working spacing between the clothed cylinder and at least one clothed neighbouring roller, for example doffer and/or licker-in, which co-operate with one another with a small spacing between their cylindrical surfaces (working spacing) at the fibre transfer points. During carding, increasingly large amounts of fibre materia] are processed per unit of time, which requires higher working component speeds and higher installed performances. The increasing throughput of fibre material (production rate), even when the working surface area remains constant, results in increased generation of heat as a result of the mechanical work. At the same time, however, the technological carding result (sliver uniformity, degree of cleaning, nep reduction etc.) is constantly being improved, which requires a greater number of effective surfaces in carding engagement and narrower settings of those effective surfaces, e.g. fixed cards and/or revolving card tops, with respect to the cylinder (tambour). The proportion of synthetic fibres being processed, which -compared with cotton -generate more heat as a result of friction when in contact with the effective surfaces (clothings) of the machine, is continually increasing. The working components of high performance carding machines are nowadays totally enclosed on all sides in order to conform to the high safety standards, to prevent the emission of particles into the spinning room environment and to minimise the need for servicing of the machines. Grids or even open, material-guiding surfaces allowing exchange of air are largely a thing of the past. The said circumstances markedly increase the input of heat into the machine, while the discharge of heat by means of convection is markedly reduced. The resulting more intense heating of high performance carding machines leads to greater thermo-elastic deformation which, on account of the non-uniform distribution of the temperature field, affects the set spacings of the effective surfaces: the spacings between cylinder and card top, doffer, fixed cards and separation sites become smaller. In an extreme case, the set gap between the effective surfaces can be completely consumed by thermal expansion, so that components moving relative to one another collide, resulting in considerable damage to the affected high performance carding machine.

Accordingly, particularly the generation of heat in the working zone of the carding machine can lead to different degrees of thermal expansion when the temperature differences between the components are too great.

Carding gaps and roller spacings on a carding machine are extraordinarily important. The carding quality stands or falls with the exact setting of those gaps (roller nips) . Under the action of heat, the rollers expand and the gaps change. In addition to expansion of the rollers caused by centrifugal force, which greatly changes the gaps, a high production rate and carding-intensive synthetic fibres additionally give rise to intense heating of the rollers. Thermally induced changes in the dimensions of the rollers occur. In order to achieve optimum carding quality it is necessary for the roller spacings to remain constant during operation. !vConstant!v means in this context that the change in spacing should be preferably less than 0.01 mm.

In a known apparatus (DE 29 48 825), in a carding machine having at least two co-operating rollers the spacing between the two rollers is changed in order to compensate for heating. This change is effected by means of additional mechanical displacement elements which are so constructed that they are able to change the spacing of the axes of the rollers in accordance with the prevailing temperature. For that purpose, the stationary framework of the carding machine is in the form of a frame having four supports (only two are shown) and having two horizontal longitudinal bars (only one is shown) . The two longitudinal bars and the supports are joined together by crossbars (not shown) to form a stable, rigid supporting frame for two rotating rollers (cylinder and doffer) which are equipped with pointed clothing and operate with a small spacing a between them. The cylinder is mounted in fixed position and so as to be rotatable about its axis by means of two bearings (of which only one is shown) which are screwed tightly to the longitudinal bars by means of screws, and is driven and rotated. The doffer is likewise mounted so as to be rotatable about its axis by means of two bearings (only one is shown) on the longitudinal bars of the framework. The bearings for the doffer are not screwed tightly to longitudinal bars, however, but are each guided by means of two collar screws so that they are displaceable parallel to the axis by a small amount of the order of 1 to 2 mm. For that purpose, slot openings are provided in the bearings for the projecting screws, which allow exact lateral guidance of the bearings while ensuring their displaceability in the longitudinal direction. By parallel displacement of the bearings in the slot openings, the spacing between the cylindrical surfaces of the two rollers can be varied. For that purpose, the machine framework is provided on each of its longitudinal bars with a fixed stop for positioning devices (displacement elements) which are inserted between the fixed stop and the bearing of the doffer. The positioning devices are capable of determining the position of their corresponding bearing in respect of that of the fixed bearing for the cylinder. For the displace-ment of the supporting element, the thermal expansion of a metal rod is utilised. For that purpose, a metal rod is fixedly anchored in the supporting elements, for example by means of threaded connections. The supply of heat required for the thermal expansion of the metal rod is generated by means of an electrical resistor wound directly around the rod, the power supply of which is regulated by a control device. A disadvantage of this apparatus is its structural complexity. A further shortcoming is that constant heating of the metal rod is necessary in order to keep the rod at a constant temperature (and accordingly expansion) Heat is used exclusively to enlarge the spacing. If, furthermore, the machine should suddenLy stop (for example as a result of a power failure) and the heating elements fail, the spacings between the cylinder and the surrounding rollers will become smaller because the adjustment unit, by virtue of its far smaller mass, is able to cool down more quickly than the cylinder. This can result in contact being made between the tambour and the surrounding rollers and It is an aim of the invention to provide an apparatus of the kind described at the beginning which avoids or mitigates the mentioned disadvantages, which has an especially simple structure and enables the setting of a pre-determined spacing between neighbouring rollers to be effected within a short space of time in the event of changes in the dimensions of the rollers.

The invention provides an apparatus on a carding machine having a carding cylinder for setting a working spacing at a fibre transfer point between the carding cylinder and a clothed neighbouring roller, the apparatus having an adjustment device operable by thermal energy to adjust said clothed neighbouring roller for adjusting the working spacing, wherein the apparatus further comprises means for actively supplying thermal energy to and/or actively dissipating thermal energy from the adjustment device, whereby the adjustment device is operable to set or reset the working spacing in the event of a change of the working spacing consequent upon a change in the dimensions of the carding cylinder and/or said clothed neighbouring roller caused by thermal expansion and/or centrifugal forces.

As a result of the measures taken according to the invention it is possible in a simple manner to maintain constant roller spacings in carding machines under the effect of heat or the effect of centrifugal force.

According to the invention, an adjustment device operable by actively supplying or dissipating thermal energy is provided for the spacing between the cylinder and, for example, the doffer roller in order to keep the spacing constant in the event of changing operating conditions. In order to bring about the desired positioning movement (which may be actively closed-loop and open-loop controllable) there is used an element for the necessary supplying and dissipation of thermal energy, which can preferably be both cooling and heating (for example a Peltier element). This allows closed-loop or open-loop control that responds very flexibly and quickly to changes of state. In some embodiments it is also possible for the cooling effect to be intensified by means of cooling bodies, fans or the like.

The desired value of the displacement travel is preferably input into a closed-loop or open-loop control means. By means of active closed-loop control it is possible to compensate for the change in spacing produced by centrifugal force. A passive adjustment system would respond to the change in spacing only after a time delay, because the change in spacing caused by centrifugal force is brought about much more quickly than a change caused by supplying thermal energy.

Preferably, in the start-up and run-down phases of the machine the positioning element of the adjustment device undergoes its greatest expansion and the doffer is moved closer to the cylinder. As the rotational speed rises and the heat increases, the temperature of the adjustment device is reduced again in order to compensate for the change in spacing caused by the increase in centrifugal force and roller temperatures. Accordingly, once a machine has become warm there is no need or very little need to effect heating or cooling if the machine has been pre-set beforehand in such a way that the spacing is ideal for a warm machine at room temperature. It is then only necessary to compensate for any fluctuations in ambient temperature or for any adjustments on the basis of a change in the choice of material. The present invention thus operates in a resource-saving manner in terms of energy consumption.

A further advantage lies in the improvement in machine safety. If, for example, the machine suddenly stops (for example as a result of a power failure) and the heat elements fail, the spacings between the cylinder and the surrounding rollers will become smaller because the adjustment unit, by virtue of its far smaller mass, is able to cool down more quickly than the cylinder. This can result in contact being made between the tambour and the surrounding rollers and working elements. In the present invention, in such emergencies the spacing is made larger.

The advantages of the invention are inter alia: * in addition to being heated, the adjustment device can also be cooled and can therefore undergo closed-loop and open-loop control more flexibly and quickly; * the opposite direction of action of the adjustment elements reduces energy consumption and offers a safeguard against damage to machinery if the machine suddenly stops.

Using the apparatus according to the invention (actor), spacings between rollers are set automatically. By means of this settability, changes in the gap caused by the centrifugal force of the cylinder and the thermal expansion of the rollers can be compensated for by means of a closed-loop control structure. Active heating and active cooling is made possible, that is to say specific temperatures of the adjustment device are implemented selectively within a short space of time. In particular, the invention -in addition to allowing active heating -also allows active cooling (heat dissipation or withdrawal of thermal energy) of the adjustment device. The device, which is able to effect both cooling and heating, allows closed-loop or open-loop control that responds very flexibly and quickly to changes of state.

Advantageously, the means for actively supplying or dissipating thermal energy is arranged both for heating and for cooling. Preferably, the means for actively supplying or dissipating thermal energy is a Peltier element. Advantageously, the Peltier element has two metal conductors (closed thermocouple) which are connected to an electrical power source. Advantageously, the direction of current flow in the metal conductors is reversible. Advantageously, a cooling body is associated with the means for actively supplying or dissipating thermal energy. In certain embodiments, the cooling body has cooling ribs or the like. In certain embodiments, a fan or the like may be associated with the device.

Preferably, the adjustment device has a thermally expandable or contractable means. Advantageously, thermal energy is actively suppliable to or withdrawable from the expandable or contractable means. Preferably, the expandable or contractable means is expandable by active supplying of thermal energy and contractable by active dissipation of thermal energy (withdrawal of thermal energy) . Advantageously, the active supplying or dissipation of thermal energy acts on the expandable or

contractable means.

In some embodiments, the expandable or contractable means is a solid body. The solid body may act as a positioning element for the neighbouring roller.

Advantageously, the solid body (positioning element) is a metal rod, a metal bar or the like. Advantageously, the solid body (positioning element) is a hollow body, for example a tube. Advantageously, the solid body (positioning element) is made of aluminium or an aluminium alloy. Advantageously, the solid body (positioning element) is extruded, for example an extruded aluminium profile. Advantageously, a transmission, gear mechanism or the like is associated with the solid body for the transfer of the expansion or contraction. Advantageously, the adjustment device has an actuating means having a kinematic reversing means. Advantageously, the device for actively supplying and/or dissipating thermal energy, for example a Peltier element, is mounted on the solid body (positioning element) . Advantageously, the solid body (positioning element) has, on its outer side, thermal insulation, a heat-protective covering or the like.

Advantageously, the connection points between the solid body (positioning element) and the surrounding components of the machine consist of a material having a low thermal conductivity coefficient. Advantageously, the connection points consist of alloyed steel, for example low-alloy steel. In one advantageous embodiment, the Peltier element is attached to the metal rod, metal tube or the like or the container, housing or the like by adhesive bonding or the like, for example by means of a heat-conductive adhesive. In another embodiment, the Peltier element is attached to the metal rod, metal tube or the like or the container, housing or the like by clamping.

In further embodiments, between the Peltier element and the metal rod, metal tube or the like or the container, housing or the like there is a heat-conductive film, heat-conductive paste or the like. Preferably, the Peltier element is attached to a flat surface of the metal rod, metal tube or of an intermediate piece (Peltier connection) for connection to a tube.

In an advantageous embodiment, the expandable and contractable means is a fluid. Advantageously, the fluid is a non-compressible fluid. Advantageously, the fluid is an oil, for example, a hydraulic oil. Preferably, the thermal expansion coefficient of the fluid is high, for example about = 7 x i0. By way of illustration, the change in the spacing may be about 0.1 mm per 10°K increase in temperature. Advantageously, the positioning element comprises a metal rod, a bar or the like.

Advantageously, the positioning element comprises a cylindrical piston. Advantageously, the adjustment device comprises a container, a housing or the like.

Advantageously, the positioning element is attached by one end to the cylinder. Advantageously, the cylinder piston and the region of the positioning element facing the cylinder piston are arranged in the container, housing or the like. Advantageously, the region of the positioning element facing away from the cylinder piston is arranged outside the container, housing or the like or projects out of the container, housing or the like. Advantageously, the fluid is present between the inner wall of the container, housing or the like and at least one end face of the piston. Advantageously, the fluid is present between the inner wall of the container, housing or the like and an end face of the piston. Advantageously, the positioning element, for example rod, bar or the like, is force-loaded. Preferably, the container, housing or the like is sealed. Preferably, the fluid is located in a sealed inner chamber of the container, housing or the like. Advantaqeously, the portion of the positioning element that projects out of the housing, container or the -10 -like is connected to the bearing of the neighbouring roller. Preferably, the return of the positioning element (displacement travel) is effected by energy dissipation (cooling) of the fluid. Advantageously, the fluid is expandable by supplying of thermal energy and the positioning element is locally displaceable by expansion of the fluid. In some embodiments, the active supplying and dissipation of thermal energy to the adjustment device is controllable by open-loop control. In certain embodiments, an open-loop control device is provided in order to take account of the supplying and dissipation of thermal energy effecting adjustment of the spacing on the basis of empirically obtained data. In certain other embodiments, the active supplying and dissipation of energy to the adjustment device is controllable by closed-loop control. Advantageously, a closed-loop control device is provided in order that the supplying and dissipation of thermal energy to the adjustment device can be adjusted to a preset desired value on the basis of measurements of the current spacing. Advantageously, thermal energy is suppliable to the adjustment device prior to the start-up phase. Advantageously, depending upon the arrangement, thermal energy is withdrawable from or suppliable to the adjustment device during the start-up phase. Advantageously, depending upon the arrangement, thermal energy is suppliable to or withdrawable from the adjustment device during the run-down phase. Preferably, thermal energy is withdrawable from the adjustment device after the run-down phase. Preferably, thermal energy is suppliable to and withdrawable from the adjustment device during the operating phase (after the start-up phase and prior to the run-down phase) Preferably, the desired value of the working spacing is presettable by calculation on the basis of the rotational speed of the cylinder and the temperatures of the cylinder, side screen and environment.

-11 -Advantageously, the actual position of the neighbouring roller relative to the cylinder is measurable by a sensor, for example a displacement sensor, spacing measuring device or the like. In certain preferred embodiments, a closed-loop controller compares the actual position and the desired position (desired value) and, in the event of a difference, in the form of a control variable influences the energy supply to the Peltier element. Advantageously, the neighbouring roller is a clothed doffer, a clothed licker-in, or a clothed worker roller of a roller card.

In some embodiments, the working spacing between the neighbouring rollers can be made smaller by supplying thermal energy to the adjustment device. In other embodiments, the working spacing between the neighbouring rollers can be made smaller by withdrawing thermal energy from the adjustment device. In certain embodiments, the working spacing between the neighbouring rollers can be made larger by supplying thermal energy to the adjustment means. In other embodiments, the working spacing between the neighbouring rollers can be made larger by withdrawing thermal energy from the adjustment device. Preferably, for setting the working spacing the neighbouring roller is mounted so as to be displaceable with respect to the cylinder. Preferably, for setting the working spacing, the neighbouring roller is mounted about a fixed pivot point with respect to the cylinder. Advantageously, the pivot point is arranged on the machine framework.

Advantageously, the roller is articulated on the fixed pivot point by means of a rotatable lever (pivot arm) Advantageously, the positioning element, for example rod, tube or the like, is articulated on the rotatable lever.

Advantageously, the rotatable lever (pivot arm) of the roller is supported on the positioning element.

Advantageously, the rotatable lever (rotation) is mounted on the positioning element. Advantageously, the positioning element is mounted at one end about a fixed -12 -pivot point. Advantageously, the rotatable lever is in the form of a bearing, framework or the like for the roller. Advantageously, the temperature of the framework walls carrying the cylinder is matchable to the working spacing by means of devices for supplying and/or dissipating thermal energy, for example Peltier elements.

Preferably, a safety valve is associated with the fluid cylinder.

The invention also provides an apparatus on a flat card or roller card for setting the working spacing between the clothed cylinder and at least one clothed neighbouring roller, for example doffer and/or licker-in, which co-operate with one another with a small spacing between their cylindrical surface (working spacing) at the fibre transfer points and in which the working spacing can be reset to a pre-determined value as a result of changes in dimensions caused by thermal expansion and/or centrifugal forces, an adjustment device operable by supplying thermal energy being provided for the neighbouring roller, wherein a device for actively supplying and/or dissipating thermal energy is provided which is associated with the adjustment device, wherein in the event of a change in the dimensions of the rollers the working spacing between the cylinder and at least one neighbouring roller can be set or reset.

Certain embodiments of the invention are described in greater detail below with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic side view of a carding machine for the apparatus according to the invention; Fig. 2 shows a side view of the cylinder and the displaceably mounted doffer with a first embodiment of the apparatus according to the invention; -13 -Fig. 2a shows a detail of the setting device according to Fig. 2; Fig. 3 shows a metal tube as positioning element having an associated Peltier element with cooling body; Fig. 4 shows in diagrammatic form the structure of a Peltier element; Fig. 5 is a controllable fluid cylinder as setting device; Fig. 6 is a block diagram of a closed-loop control device having an apparatus according to the invention for setting the spacing between two rollers; Fig. 7 is a side view of a cylinder with a pivotally mounted doffer showing a first arrangement (linkage) of the positioning element; Fig. 8 is a side view of a cylinder with a pivotally mounted doffer showing a further arrangement (linkage) of the positioning element; Fig. 9 is a side view of a cylinder with two pivotally mounted doffers, each with an arrangement of the positioning element; Fig. 10 is a side view of the cylinder with a pivotally mounted licker-in with an arrangement of the positioning element; Fig. 11 is a side view of a detail of the cylinder and pivotally mounted doffer with a controllable fluid cylinder as positioning element and safety valve, and Fig. 12 is a side view of the cylinder showing a licker-in and doffer unit as well as the arrangement of the positioning elements with respect to the framework walls supporting the cylinder.

-14 -Fig. 1 shows a carding machine, for example a Trützschler flat card IC 07, having a feed roller 1, feed table 2, lickers-in 3a, 3b, 3c, cylinder 4, doffer 5, stripper roller 6, nip rollers 7, 8, web guide element 9, sliver funnel 10, delivery rollers 11, 12, revolving card top 13 with card top guide rollers 13a, 13b and card flats 14, can 15 and coiler 16. The directions of rotation of the rollers are indicated by curved arrows. Reference letter M denotes the centre point (axis) of the cylinder 4, M2 the centre point of the doffer 5 and M3 the centre point of the licker-in 3c. Reference numera] 4a denotes the clothing and reference numeral 4b the direction of rotation of the cylinder 4. Reference numeral 5a denotes the clothing and 5b the direction of rotation of the doffer 5. Reference letter B denotes the direction of rotation of the revolving card top 13 in the carding position and reference letter C denotes the return transport direction of the card flats 14, with 62', 62'' denoting fixed functional elements and 18 a cowling under-neath the cylinder 4. The arrow A indicates the working direction.

Referring to Fig. 2, a stationary framework 20 of a flat card or roller card in the form of a frame is provided with four supports 21 (only two are shown) and two horizontal longitudinal bars 22 (only one is shown) The two longitudinal bars and the supports are joined together by means of crossbars (not shown) to form a stable, rigid supporting frame for two rotating rollers 4 and 5 which are equipped with pointed clothing and operate with a small spacing a between them. The cylinder 4 is mounted in fixed position and so as to be rotatable about an axis M by means of two supporting elements 24 (of which only one is shown in Fig. 2), which are screwed tightly to the longitudinal bars with screws 23a, 23b, and is driven and rotated in the clockwise direction 4b by -15 -devices not shown in the drawing. The cylinder 4 carries a pointed clothing 4a on its cylindrical surface. The doffer is likewise mounted so as to be rotatable about its axis N2 by two supporting elements 25 (only one is shown) on the longitudinal bars 22 of the framework 20. The supporting elements are not screwed tightly to the longit-udinal bars, however, but are each guided by means of two prismatic guides 26 (see Fig. 2a) in such a way that they are displaceable parallel to the axis by a small amount of the order of from 1 to 2 mm. By parallel displacement of the supporting elements 25 it is thus possible for the spacing between the cylindrical surfaces or clothings 4a and 5a of the rollers 4 and 5 to be varied in the direction of arrows N, N. The doffer 5 is likewise provided with a pointed clothing 5a on its cylindrical surface. For the transfer of the fibres from the cylinder 4 to the doffer 5, crucially important factors are the spacing a between the cylindrical surfaces of the two rollers, in addition to other parameters, such as, for example, the surface speed of the two rollers and the nature of the pointed clothing. Good working ratios between the rollers can be ensured only when the spacing a is kept within exact and very narrow tolerances. In such an arrangement, in the case of roller diameters of about from 0.20 m to 1.5 m and roller widths of up to about 2 m the optimum value for the spacing a lies in a range of about 0.05 mm < a < 0.3 mm, the lower limit of the spacing a not being a technological requirement but being main- tained only in order to avoid mutual contact or inter-ference between the clothing tips of the two rollers.

There is otherwise a risk of fire and mechanical damage to the expensive pointed clothings. The spacing a is there-fore extremely small in comparison with the dimensions of the rollers. The increase in diameter brought about by the rise in roller temperature is, as has been established by experiments, of the order of about 0.08 mm per 10°C rise -16 -in temperature, which entirely corresponds to the order of magnitude of the optimum value of the spacing a. Similar deformation is caused by the effect of centrifugal force.

In order to set the spacing a to a desired value, the machine frame has to be provided on each of its longitudinal bars with a fixed stop 27 for positioning elements 28 which are inserted between the fixed stop 27 and the supporting element 25. The positioning elements 28 are capable of determining the position of their corres-ponding supporting element 25 in respect of the position of the fixed supporting element 24. The control of the positioning elements is effected by means of closed-loop control devices (see Fig. 6) . A Peltier element 29 is associated with each of the positioning elements 28 as a device for supplying or dissipating thermal energy.

In the embodiment illustrated in Fig. 2a, the thermal expansion or contraction of a metal rod as positioning element 28 is utilised for the displacement of the supporting element 25 (bearing) . For that purpose, the metal rod 28 is fixedly anchored in the supporting element and in the stop 27, for example by means of threaded connections. The active supplying of heat and the active withdrawal of heat required for the thermal expansion and the thermal contraction, respectively, of the metal rod 28 are generated by means of the Peltier element 29, the power supply of which is regulated by the closed-loop control device (see Fig. 6) . The displaceable attachment of the supporting element 25 to the longitudinal bar 22 is effected by means of prismatic guides 26.

In an embodiment shown in Fig. 3, the positioning element 28 is in the form of a metal tube. The expandable or contractable body of the positioning element 28 preferably consists of a material having a high thermal expansion coefficient and at the same time high strength (for example aluminium) . The body shown in Fig. 3 is an aluminium tube (thermal expansion coefficient = 23.8 x -17 - 1O [1/°K]) . Being in the form of a hollow body (tube), the body has as little mass as possible in order that it can be heated and cooled as quickly as possible.

Furthermore, it is insulated so that it is not able to give up the supplied heat to the environment. The insulation 30 can be effected externally, for example by means of a foam rubber tube. The connection points 31a, 31b to the surrounding components of the machine consist, unlike the body of the positioning element 28, of a material having a low thermal expansion coefficient in order to withdraw as little heat as possible from the body and likewise to insulate the positioning element 28. Here (low-)alloyed steel, for example, is suitable. The Peltier element 29 requires a flat surface for mounting. If a round tube as in Fig. 3 is used, it is necessary to attach an intermediate piece 32 (Peltier connection) to the tube (for example using heat-conductive adhesive or screws) in order to obtain a flat surface. It is also possible for the body of the positioning element 28 to be shaped directly with a flat surface, for example in the form of an extruded aluminium profile. A cooling body 33 is adhesively bonded directly to the Peltier element 29; it can also be attached by clamping.

When, in accordance with Fig. 4, two different electrical conductors are joined together at their ends (for example soldered connection) and the electrical conductors are supplied with a voltage, the Peltier element 29 operates as a kind of heat pump and transports the heat from one side of the element to the other. The side giving up heat is cold and the other warm. When the polarity of the energy supply 34 is reversed, the cold and warm sides change over. The Peltier element 29 accordingly produces, by means of the energy supply 34, a temperature difference between the two sides of the element. If cooling is required, the heat on the warm side must be dissipated as well as possible in order that the side to -18 -be cooled can become all the colder. Conversely, during heating, on the cold side as much heat as possible must be absorbed in order that the side to be heated can become all the warmer. According to Fig. 4, negatively doped semi-conductors 35a, 35b (n-doped) and positively doped semi-conductors 36a, 36b (p-doped), always alternately, are joined together at their ends on copper plates 37a, 37b, 37c. Usually the copper plates 37a, 37b, 37c are covered by a respective ceramic plate 38a, 38b for the warm side and for the cold side.

In order to heat the body of the positioning element 28 as quickly as possible, the body is insulated from the environment. Otherwise the body would transmit a portion of the heat received directly to the environment. In order to cool the body of the positioning element 28 as quickly as possible, it has a large cooling surface which is able to give up heat quickly to the environment. The Peltier element 29 is clamped or adhesively bonded between the body of the positioning element 28 to be heated or cooled and the cooling body 33, it being important that there is no thermal bridge between the cooling body 33 and the body of the positioning element 28. If such a bridge were to be present, the Peltier element 29 would not be able to produce a temperature difference between the cooling body 33 and the body of the positioning element 28, because the temperature difference would be directly compensated for by thermal conduction. The cooling body 33 is consequently decoupled from the component to be heated or cooled. This offers the advantage that, during heating, the cooling body 33 need not be heated too, with the result that the heating operation takes place more quickly.

By virtue of the large surface area of the cooling body 33, the Peltier element 29 is capable of withdrawing heat from the environment and pumps it into the body of the positioning element 28. If cooling is then to be effected (for example in an emergency or in the event of a -19 -crash), the polarity of the power supply 34 of the Peltier element 29 is reversed. Immediately, the heat previously pumped into the body of the positioning element 28 is removed again from the cooling body 33 and the body of the positioning element 28 contracts. In this case, as a result of reversing the polarity of the current, active cooling is therefore effected, unlike in the prior art.

The cooling process could also be actively supported and thus accelerated by the use of a fan (not shown) blowing towards the cooling body 33. The operation is quicker not only in the case of active cooling as a result of polarity reversal. Just the switching-off of the Peltier element 29 and the passive cooling by way of the cooling body 33 (which is expediently usable only in conjunction with a Peltier element 29) bring about a rapid cooling process.

Because the heat not only is dissipated by way of the entire surface of the body of the positioning element 28 but is chiefly pumped out by way of the Peltier element 29 and the cooling body 33, it is possible, and also expedient, to insulate the positioning element 28 in order to speed up the heating process.

By the use of the Peltier element 29 in combination with a cooling body 33 (and possibly a fan) the heating and cooling processes accordingly take place more quickly than when, for example, conventional heating elements are used. The regulating dynamics of an adjustment unit for setting the spacing of the cylinder 4 and the doffer 5 with a Peltier element 29 are consequently higher than in the case of previously known adjustment devices.

In an embodiment shown in Fig. 5, a fluid 44 having a high volumetric expansion coefficient is located in a leak-proof container 40. A piston 42, which is spring-loaded, for example by two compression springs 41a, 41b, and has a piston rod 43, is used for applying a load to the fluid 44 (overpressure) . When heated, the fluid 44 expands. The projecting piston rod 43 moves outwards.

-20 -Connected to a roller, the roller moves away from the cylinder 4. When the fluid 44 cools, the process takes place in reverse. The necessary energy for heating the fluid 44 or for withdrawing heat from the fluid 44 is implemented by the Peltier element 29 which is attached to the container 40. The piston rod 43 has, for example, a thread, so that initial setting can be carried out. By the correct choice of fluid, piston surface area, spring-bias and fluid volume, the apparatus is adaptable in respect of adjustment force and adjustment travel. The housing 40 is divided into a housing part 40a in which the compression springs 41a, 41b are]ocated and a housing part 40b in which the hydraulic oil is located. The piston rod 43 and the piston 42 are displaceable in the direction of arrow F in the event of thermal expansion and in the direction of arrow G in the event of withdrawal of heat. The adjustment movement for the roller is transmitted via piston rod. 43.

In the diagram, reference numeral 44 indicates the fluid; reference numeral 63 indicates the adjustment device.

With reference to Fig. 6, the Peltier element 29 is connected into a closed-loop control circuit. A desired value setter 46, for example a memory, for a desired (preset) working spacing is associated with a closed-loop controller 45, for example a PID closed-loop controller.

Electrically connected to the closed-loop controller 45 as measuring device is a sensor 27, for example a displacement sensor, which inputs measured variables into the closed-loop controller 45. Also electrically connected to the closed-loop controller 45 is the Peltier element 29 to which control variables are output from the closed-loop controller 45. The Peltier element 29 is attached to the positioning element 28 (see Fig. 3) which acts on an adjustment device 48 (see Fig. 2) for setting or resetting the working spacing. Reference numeral 49 indicates an element for inputting disturbing factors.

The desired value for the working spacing is preset -21 -by the calculations based on the rotational speed of the cylinder and the temperatures of the cylinder 4, the side screen and the environment (T-CON) . The actual position of the doffer 5 with respect to the cylinder 4 is measured by way of the sensor 47 (for example a displacement sensor) The closed-loop controller 45 (preferably a PID closed-loop controller) compares the actual position with the desired value and regulates the energy supply 34 of the Peltier element 29 accordingly (see Fig. 4) . By heating or cooling with the Peltier element 29, the body of the positioning element 28 or the fluid 44 expands or contracts again. Disturbing factors, such as, for example, a change in ambient temperature, can have an adverse effect on the working spacing then established. The sensor 47, however, measures the change in the working spacing, the closed-loop controller 45 makes a further adjustment and thus the closed-loop control circuit is closed.

By skilful arrangement of a positioning element 28 between the doffer 5 and the framework 20 it is possible to compensate for the disadvantage of a relatively low expansion coefficient of a solid (metal), as shown in Figures 7 and 8.

In the embodiment of Fig. 7, the doffer 5 is mounted so as to be rotatable about a fixed pivot point 50 (pivot bearing) on the framework 20 of the machine. The pivot arm 51 of the doffer 5 is supported at one end 52 on the fixed body of the positioning element 28. The pivot arm 51 is rotatable about the pivot point 50 in the direction of arrows H, I. When the body of the positioning element 28 is heated with the Peltier element 29, the body expands and the working spacing a becomes smaller. Conversely, the working spacing a becomes larger when the body of the positioning element 28 is cooled. The closer the positioning element 28 is arranged to the pivot point 50, the smaller the expansion needs to be in order to achieve the desired travel. The other end of the positioning -22 -element 28 is articulated on a fixed pivot point 53 (pivot bearing) which is advantageously mounted on the framework 20.

Because the Peltier element 29 is also able to effect cooling by polarity reversal of the current flow (see Fig. 4, position 34), it is likewise possible to cause the positioning element 282 to act in the opposite direction, as in the embodiment shown in Fig. 8. The pivot arm 51 (lever arm) is mounted on the positioning element 282 at end 52. The other end of the positioning element 282 is articulated in fixed position on the pivot point 54. When the positioning element 282 in this arrangement is cooled, it contracts and the working spacing a becomes smaller.

The constructions in accordance with Figures 7 and 8 have the advantage that the doffer 5, which is mounted so as to be rotatable or pivotable about pivot point 50, -and optionally the entire outlet module arranged down-stream of the cylinder 4, including the stripper roller 6, the nip rollers 7, 8, the web guide element 9, the sliver funnel 10 and the delivery rollers 11, 12 -are by virtue of their own weight loaded by gravity in the direction of arrow H, so that a fixing means is unnecessary.

Advantageously, a stop (not shown) or the like is provided in order that contact between the clothings 4a and 5a of the cylinder 4 and the doffer 5, respectively, is ruled out.

Fig. 9 shows an embodiment in which the cylinder 4 co-operates with two downstream doffers 5 and 52 which are each pivotable by means of a respective rotatable lever arm 51a, Sib about fixed pivot points, each of which is articulated on a respective positioning element 28a, 28b. The positioning elements 28a and 28b each co-operate with a respective Peltier element 29a, 29b (not shown in Fig. 9), with the result that the working spacings a1 and a2, respectively, can be set or reset.

Fig. 10 shows an embodiment in which the cylinder 4 -23 -co-operates with a pivotally mounted upstream licker-in 3 which is pivotable by means of a rotatable lever arm 55 about a fixed pivot point 56, the lever arm 55 being articulated on the positioning element 28 which co-operates with a Peltier element 29c (not shown in Fig. 10), with the result that the working spacing between the cylinder 4 and the licker-in 3 (i.e. the clothings 4a and 3'', respectively, thereof) can be set or reset. The pivot arm 55 is rotatable about the pivot point 56 in the direction of arrows K, L. In the embodiment of Fig. 11, the fluid cylinder 40, which may for example be a fluid cylinder according to Fig.5, is equipped with a safety valve 60 (for example an electrically operable 2/2-way valve or an electrically unblockable non-return valve). The adjustment unit is arranged in such a way that opening the valve 60 inevitably results in enlargement of the spacing a between the cylinder 4 and the doffer 5, SO that in an emergency major damage to the machinery is avoided. For example: a lap is formed and is detected by a separate lap detection device 61 at a stripper roller 6. The valve 60 is then opened. The increase in the spacing could be effected, for example, by the weight force of the doffer roller 5 pushing in the piston 42 (see Fig. 5) and accordingly forcing the fluid 44 out of the cylinder 40. A trapezoidal framework is required, the support means of which serves as a slide rail for the doffer 5, SO that the adjustment unit of the roller 5 is prevented from acting in the horizontal direction. Another possibility would be pendulum-like mounting of the doffer 5 about a pivot point (see Fig. 7, 8) According to Fig. 12, before the carding machine is set in operation, for example at room temperature, between the cylinder 4 and the licker-in 3c there is a spacing b on the one hand and between the cylinder 4 and the doffer 5 there is a spacing a1 on the other hand, for -24 -example 8/1000" in each case. When the carding machine is in operation, after the machine, especially the rollers, has warmed up, the spacings between the cylinder 4 and the licker-in 3c and the cylinder 4 and the doffer 5 have reduced to a2 and b2, respectively, for example 2/1000" in each case. By means of the Peltier elements 29 and 292 on and in the bearing supports 21', 21'', respectively (and in the bearing supports in the wall of the framework on the other side of the carding machine, which are not shown), the bearing supports are expanded in the vertical direction. As a result, the cross-member 22, the bearing 24 (and the cross-member and bearing on the other side, which are not shown) and the axis M, together with the cylinder 4, are lifted upwards likewise in the vertical direction. In that way, the spacing c between the machine base or framework base and the centre point M increases to spacing c2. At the same time, the spacings al and bl are increased to spacings a2 and b2, respectively, which can be determined by geometric calculation. The spacings el arid dl between the machine base or framework base and the centre point M2 of the shaft of the doffer 5 and the centre point N3 of the shaft of the licker-in 3, respectively, remain the same.

The temperature decreases from the level of the rollers via the side screens as far as the machine framework. According to the invention, compensation for the changes in the dimensions of the rollers is effected selectively and with very low heat output or cooling, as the case may be. The machine framework 20 is divided up thermally in such a way that the cylinder 4 is raised or lowered by heating of its supports 21', 21'' which are !vinsulated from the remainder of the framework. Stepwise or stepless setting of the temperature of the Peltier elements 28, 282 can be provided. According to the invention, active supplying or dissipation of heat is implemented.

-25 -The working width (not shown) of the cylinder 4 and of the at least one neighbouring roller is, for example, from 1000 mm to 2000 mm.

As a result of the measures taken according to the invention, that is to say active supplying of heat and active withdrawal of heat at the positioning elements for the at least one roller adjacent to the cylinder 4, the working nip is in an elegant way set or reset to desired (pre-determined) values within a short space of time.

In order in an emergency to effect very rapid cooling of the positioning element 28 (expandable and contractable tube), use is advantageously made of the effect that compressed air that is "depressurising" undergoes very intense cooling. If, for example, compressed air having a pressure of 6 bar above ambient pressure is released from a valve into the environment, the previously compressed air is able to expand again and assume ambient pressure.

As a result of that expansion, the air is cooled within seconds to less than -100°C. Such a process is referred to in thermodynamics as an "isentropic change of state". For its implementation it is possible for a pneumatic valve to be mounted at the positioning element 28 (expandable and contractable tube) and opened in an emergency. By means of the cold air that is to flow through the tube it is possible within a short space of time to implement a roller spacing a of several thousandths of an inch. The cooling is effected by compressed air that is depressur-ising.

Claims

-26 -Cia iins 1. An apparatus on a carding machine having a carding cylinder for setting a working spacing at a fibre transfer point between the carding cylinder and a clothed neighbouring roller, the apparatus having an adjustment device operable by thermal energy to adjust said clothed neighbouring roller for adjusting the working spacing, wherein the apparatus further comprises means for actively supplying thermal energy to and/or actively dissipating thermal energy from the adjustment device, whereby the adjustment device is operable to set or reset the working spacing in the event of a change of the working spacing consequent upon a change in the dimensions of the carding cylinder and/or said clothed neighbouring roller caused by thermal expansion and/or centrifugal forces.
2. An apparatus according to claim 1, wherein the means for actively supplying or dissipating thermal energy is arranged both for heating and for cooling.
3. An apparatus according to claim 1 or claim 2, wherein the means for actively supplying or dissipating thermal energy is a Peltier element.
4. An apparatus according to claim 3, wherein the Peltier element has two metal conductors, which are connected to an electrical power source.
5. An apparatus according to claim 4, wherein the direction of current flow in the metal conductors is reversible.

-27 -
6. An apparatus according to any one of claims 1 to 5, wherein a cooling body is associated with the means for actively supplying and/or dissipating thermal energy.
7. An apparatus according to claim 6, wherein the cooling body has cooling ribs or the like.
8. An apparatus according to any one of claims 1 to 7, wherein the means for actively supplying and/or actively dissipating thermal energy from the adjustment device includes a fan.
9. An apparatus according to any one of claims 1 to 8, wherein the adjustment device comprises thermally expandable or contractable means.
10. An apparatus according to claim 9, wherein thermal energy is actively suppliable to or withdrawable from the thermally expandable or contractable means.
11. An apparatus according to claim 10, wherein the thermally expandable or contractable means is expandable by active supplying of thermal energy and contractable by active withdrawal of thermal energy.
12. An apparatus according to any one of claims 9 to 11, wherein the thermally expandable and contractable means is a solid body.
13. An apparatus according to claim 12, wherein the solid body is a metal rod, or a metal bar.
14. An apparatus according to claim 12, wherein the solid body is a hollow body.
15. An apparatus according to any one of claims 12 to 14, -28 -wherein the solid body is made of aluminium or an aluminium alloy.
16. An apparatus according to any one of claims 12 to 15, wherein the solid body is extruded.
17. An apparatus according to any one of claims 12 to 16, further comprising a transmission, or gear mechanism for transfer of the expansion or contraction from the solid body to the neighbouring roller.
18. An apparatus according to any one of claims 12 to 17, wherein the adjustment device has an actuating means having a kinematic reversing means.
19. An apparatus according to any one of claims 12 to 18, wherein the means for actively supplying thermal energy to or actively dissipating thermal energy from the adjustment device is mounted on the solid body.
20. An apparatus according to any one of claims 12 to 19, wherein the solid body is thermally insulated on its outer side.
21. An apparatus according to any one of claims 12 to 20, wherein any connection points between the solid body and any surrounding components of the carding machine consist of a material having a low thermal conductivity coefficient.
22. An apparatus according to claim 21, wherein the connection points consist of alloyed steel.
23. An apparatus according to any one of claims 12 to 22, wherein the means for actively supplying thermal energy and/or actively dissipating thermal energy is attached to -29 -the solid body or to a housing therefor by means of a heat-conductive adhesive.
24. An apparatus according to any one of claims 12 to 23, wherein the means for actively supplying thermal energy and/or actively dissipating thermal energy is attached to the solid body or a housing therefor by clamping.
25. An apparatus according to any one of claims 12 to 24, wherein between the means for actively supplying thermal energy and/or actively dissipating thermal energy and the solid body or container therefor there is a heat-conductive film or heat-conductive paste.
26. An apparatus according to any one of claims 12 to 26, wherein the means for actively supplying thermal energy and/or actively dissipating thermal energy is attached to a flat surface of the solid body or of an intermediate piece for connection to the solid body.
27. An apparatus according to any one of claims 9 to 11, wherein the thermally expandable or contractable means is a fluid.
28. An apparatus according to claim 27, wherein the fluid is a non-compressible fluid.
29. An apparatus according to claim 27 or claim 28, wherein the fluid is an oil.
30. An apparatus according to claim 29, wherein the oil is a hydraulic oil.
31. An apparatus according to any one of claims 27 to 30, wherein the thermal expansion coefficient of the fluid is high.

-30 -
32. An apparatus according to any one of claims 27 to 31, wherein the change in the spacing is about 0.1 mm per l0°K increase in temperature.
33. An apparatus according to any one of claims 27 to 32, further comprising a positioning element comprising an elongate metal member for transmitting an expansion or contraction to the neighbouring roller.
34. An apparatus according to claim 33, wherein the positioning element is connected to a cylindrical piston.
35. An apparatus according to claim 34, wherein the adjustment device comprises a housing.
36. An apparatus according to claim 35, wherein the positioning element is attached by one end to the cylindrical piston.
37. An apparatus according to claim 36, wherein the cylindrical piston and the region of the positioning element facing the cylinder piston are arranged in thehousing.
38. An apparatus according to claim 36, wherein the region of the positioning element facing away from the cylinder piston is arranged outside the housing or projects out of the housing.
39. An apparatus according to any one of claims 35 to 38, wherein the fluid is present between the inner wall of the housing and at least one end face of the piston.
40. An apparatus according to any one of claims 35 to 39, wherein the positioning element, is force-loaded.

-31 -
41. An apparatus according to any one of claims 35 to 40, wherein the housing is sealed.
42. An apparatus according to any one of claims 35 to 41, wherein the fluid is located in a sealed inner chamber of the housing.
43. An apparatus according to any one of claims 35 to 42, wherein a portion of the positioning element that projects out of the housing is connected to a bearing of the neighbouring roller.
44. An apparatus according to any one of claims 33 to 43, wherein the return of the positioning element is effected by energy dissipation of the fluid.
45. An apparatus according to any one of claims 33 to 44, wherein the fluid is expandable by supplying of thermal energy and the positioning element is locally displaceable by expansion of the fluid.
46. An apparatus according to any one of claims 33 to 45, wherein a safety valve is associated with the fluid housing.
47. An apparatus according to any one of claims 1 to 46, wherein the active supplying and dissipation of thermal energy to the adjustment device is controllable by open-loop control.
48. An apparatus according to claim 47, wherein an open-loop control device is provided, the control device being arranged to take account of the supplying and dissipation of thermal energy effecting adjustment of the spacing on the basis of empirically obtained data.

-32 -
49. An apparatus according to any one of claims 1 to 46, wherein the active supplying and dissipation of energy to the adjustment device is controllable by closed-loop control.
50. An apparatus according to claim 49, wherein a closed-loop control device is provided, the control device being so arranged that the supplying and dissipation of thermal energy to the adjustment device can be adjusted to a preset desired value on the basis of measurements of the current spacing.
51. An apparatus according to any one of claims 1 to 50, wherein thermal energy is suppliable to the adjustment device prior to the start-up phase.
52. An apparatus according to any one of claims 1 to 51, wherein, if desired, thermal energy is withdrawable from or suppliable to the adjustment device during the start-up phase.
53. An apparatus according to any one of claims 1 to 52, wherein, if desired, thermal energy is suppliable to or withdrawable from the adjustment device during the run-down phase.
54. An apparatus according to any one of claims 1 to 53, wherein thermal energy is withdrawable from the adjustment device after the run-down phase.
55. An apparatus according to any one of claims 1 to 54, wherein thermal energy is suppliable to and withdrawable from the adjustment device during the operating phase (after the start-up phase and prior to the run-down phase) -33 -
56. An apparatus according to any one of claims 1 to 55, wherein a desired value of the working spacing is presettable by calculation on the basis of the rotational speed of the cylinder and the temperatures of the cylinder, a side screen adjacent to the cylinder, and environment.
57. An apparatus according to any one of claims 1 to 56, wherein the actual position of the neighbouring roller relative to the cylinder is measurable by a sensor.
58. An apparatus according to claim 57, wherein a closed-loop controller compares the actual position and the desired value and, in the event of a difference, in the form of a control variable influences the energy supply to the means for actively supplying and/or dissipating thermal energy.
59. An apparatus according to any one of claims 1 to 58, wherein the carding machine is a flat card or roller card.
60. An apparatus according to any one of claims 1 to 59, wherein the neighbouring roller is a clothed doffer.
61. An apparatus according to any one of claims 1 to 59, wherein the neighbouring roller is a clothed licker-in.
62. An apparatus according to any one of claims 1 to 59, wherein the neighbouring roller is a clothed worker roller of a roller card.
63. An apparatus according to any one of claims 1 to 62, wherein the working spacing between the neighbouring roller and the carding cylinder can be made smaller by supplying thermal energy to the adjustment device.-34 -
64. An apparatus according to any one of claims 1 to 62, wherein the working spacing between the neighbouring roller and the carding cylinder can be made smaller by withdrawing thermal energy from the adjustment device.
65. An apparatus according to any one of claims 1 to 62, wherein the working spacing between the neighbouring roller and the carding cylinder can be made larger by supplying thermal energy to the adjustment means.
66. An apparatus according to any one of claims 1 to 62, wherein the working spacing between the neighbouring roller and the carding cylinder can be made larger by withdrawing thermal energy from the adjustment device.
67. An apparatus according to any one of claims 1 to 66, wherein for setting the working spacing the neighbouring roller is mounted so as to be displaceable with respect to the cylinder.
68. An apparatus according to claim 67, wherein, for setting the working spacing, the neighbouring roller is so mounted about a fixed pivot point that is pivotable with respect to the cylinder.
69. An apparatus according to claim 68, wherein the pivot point is arranged on the machine framework.
70. An apparatus according to claim 68 or claim 69, wherein the roller is articulated on the fixed pivot point by means of a rotatable lever.
71. An apparatus according to claim 70, wherein positioning element of the adjustment device for adjusting the position of the neighbouring roller is articulated onthe rotatable lever.-35 -
72. An apparatus according to claim 70, wherein the rotatable lever of the roller is supported on the positioning element.
73. An apparatus according to any one of claims 1 to 72, wherein the rotatable lever is mounted on the positioning element.
74. An apparatus according to claim 72, wherein the positioning element is mounted at one end about a fixed pivot point.
75. An apparatus according to any one of claims 70 to 74, wherein the rotatable lever is in the form of a bearing or framework for the roller.
76. An apparatus according to any one of claims 70 to 75, wherein the carding cylinder is carried between framework walls, the temperature of the framework walls being matchable to the working spacing by means of devices for actively supplying and/or dissipating thermal energy.
77. Apparatus on a flat card or roller card for setting the working spacing between the clothed cylinder and at least one clothed neighbouring roller, for example doffer and/or licker-in, which co-operate with one another with a small spacing between their cylindrical surfaces (working spacing) at the fibre transfer points and in which the working spacing can be reset to a pre-determined value as a result of changes in dimensions caused by thermal expansion and/or centrifugal forces, an adjustment device operable by supplying thermal energy being provided for the neighbouring roller, wherein a device for actively supplying and/or dissipating thermal energy is provided which is associated with the adjustment device, wherein in -36 -the event of a change in the dimensions of the rollers the working spacing between the cylinder and at least one neighbouring roller can be set or reset.
78. An apparatus on a carding machine for setting a working spacing between a carding cylinder and a neighbouring roller of said carding machine, the apparatus being substantially as described herein with reference to and as illustrated by anyone of Figs 1, 2, 2a and 3 to 12.