DE3712263A1 - Process for producing tyre starting material and winding and cutting machine - Google Patents

Abstract

Process and device for the production of tyre starting material. Rubber band (10) with inlaid reinforcing material, coming from an extruder (3), is guided in a winding machine (5) with an endless belt device along a helical path and the edges of the rubber band (10) are bonded to one another such that a tube (50) is produced. From the latter, individual pices (51) are cut off and are further processed by slitting along a circumferential line or a helical line (54) to form a rectangular or rhomboidal mat (52, 53). These mats can be cut up in a conventional manner to form the strip-shaped starting material. <IMAGE>

Description

For the tire production you need fiber or cord-reinforced, so-called "green" rubber layers (Karkas and radial material in strips), which today can be manufactured industrially as follows:

The cords or threads are in a cross head an extruder with unvulcanized ("green") rubber encased, with an approximately 80 to 120 mm wide band arises. The band is continuously equal in pieces Cut length with their narrow edges changed and connected to each other by pressing so that a rubber plate reinforced with inserts or mat is created, which in technical terms is called "layer" referred to as. As a raw material for carcasses rectangular layers, while for the tread Radial stripes have a rhomboid geometry receives. Usually only 60 to 100 mm wide, encased rubber bands used; the diagonally cut to length Ribbon strips are much shorter.

The production of the rubber layers from individual Tape strip is labor intensive and with numerous mistakes possibilities afflicted. Because of the manufacture of the rubber Bandes in the extruder must be processed continuously become, d. H. no processing stoppage may occur. That is why it is important to process as easily as possible application principle.

That's why the rubber has already been considered tape wound on a rotating drum (US-PS 41 26 720) while the drum is moving in the axial direction emotional. A disadvantage here is the time it takes to detach the strongly adhesive tubular rubber layer from the cylinder considering that there is always new rubber band accrues from the extruder and must be further processed.  

You already have the rubber tube along the Let drum axis wander (US-PS 34 86 962), where one rotating thread arranged along the drum shell destangen has provided that the resulting rubber tube move in the axial direction. The still soft, sticky rubber closes the threads so that operational safety appears endangered. The facility is also regarding of the pipe diameter generated and those to be processed Rubber bands are not flexible enough.

In another known system (US-PS 13 23 212 and 31 57 545) the pipe produced migrates from above down and is slit open to avoid the resulting To be able to wind up rubber mat tape. The disadvantage is however, the fact that the slit of the rubber tube is under tension and the insert reinforcements afterwards others are severed freely, whereby they follow each other individually relax each other, causing distortion in the sticky, not yet vulcanized rubber (filled with fillers Latex) between the curved and the straight cut Deposit is coming. At the side edges of the manufactured Rubber band the distortions do not recede, i.e. these margins are undulated and must be rejected be cut off.

The invention is based on the object Process for the production of tire raw material create using a simple, new principle so that the throughput increases and operational disruptions less are to be feared, which leads to good quality products and can be used flexibly.

In the invention, reinforcing material (Steel wires, strands, fibers, threads) in one extruder head covered with rubber, so that an endless band arises, like in principle this is already being done. What is new is that Belt on an endless belt device along one Screw path is guided. According to the screw turns border the tape edges precisely and are joined together tied so that a - wound - material tube is formed, which over the Area of the belt direction grows out and from there again and again  Pipe section of the desired length is separated. That ever because the separated piece of pipe is removed (as quickly as possible), to make room for the renewable pipe. The on successively produced pipe sections are stress-free cut open to insert rubber layers to win. This material then becomes Karkas Cut or radial tire stock.

While you have this pipe material with you too overlapping edges, it is preferred that to join the band edges in the butt joint The exact distance of the insert mat can be determined rialien from each other, without any additional processing steps, such as trimming the edges, should apply. Any beads on the butt joint smoothed by pressing on both sides. The method is economical and far more precise than before usual procedures possible.

The separation of the pipe pieces to the flat rubber mats or layers can vary depending on the intended next processing approximately parallel to the pipe axis or at an angle to the insert material.

The invention also relates to a winding machine and a cutting machine for performing the method.

The winding machine shows a number of rolls that are arranged distributed around a circumference and their axes are rotatably mounted in the machine frame. The roles are with guidance facilities for one or more Endless straps to this or this along a Helix on the circumference of the cylinder surrounding the rollers to lead it. At least one more pulley is provided inside the cylinder to the or the Tension the belt and from the end of the screw line too to redirect their beginning. At least it matters drivable around the belt or belts along its their helical path and the inner return path to drive. The winding machine is rotating Snail comparable, but the point of contact between the snail and the rubber band without slippage,  because a certain surface element of the rubber band one and the same surface element of the belt over a longer distance remains in the system before the belt is returned to its starting point. (At a Snail runs a certain surface element in a circle and does not move along a screw path.) The tube produced with the winding machine leaves the Her position range formed by the belt device and grows into a storage area, in which pipe pieces of the desired length are cut off.

The winding machine is within a predetermined area to different pipe diameters adjustable by increasing the pitch circle of the rollers or is made smaller. The pulley, which the belt leads back to itself, is as a tension roller and to a certain extent Supply roll trained to the excess belt length to be recorded in a loop.

The cutting machine according to the invention has a trough shaped frame with swiveling side cheeks, the one with rollers for rotating the recorded one Pipe piece are provided. The cutter is adjustable in terms of their cutting plane and along the Movable frame. If the rollers do not the pipe section rotate and the cutter with its cutting plane aligned in the axial direction are limited rectangular cut rubber mats and when the rolls are over adjusted speed and the cutting device is tilted while ver along the device drives, a helix is cut and it ent stands a rhombus-shaped rubber mat.

Embodiments of the invention are based on the drawing. It shows:

Fig. 1 is a schematic diagram of the overall system,

Fig. 2 is a perspective of the installation in a simplified modified embodiment,

Fig. 3 is a view from above of a winding machine,

See Fig. 4, the winding machine from the side,

Fig. 5, the winding machine, the end face on the section VV seen in FIG.

Fig. 6, the winding machine shown in Fig. 5, but in more detail,

Fig. 7 is a left side view of the chuck of the winding machine according to Fig. 6,

Fig. 8 is a view similar to FIG. 6, however, with further details

Fig. 9 shows a section through a driven roller,

Fig. 10 is a section through one idler roller,

Fig. 11 is an enlarged detail of FIG. 9 or 10,

Fig. 12 is a development of the arrangement of rollers of Fig. 8,

Fig. 13 shows a further scheme of rollers and three clamping rollers,

FIG. 14 is a diagram with four tensioning rollers,

Fig. 15 is a scheme for separating a rubber pipe in a rectangular or a rhombus-shaped rubber mat and the further cutting of these mats for example radial material,

Fig. 16 shows a cutting machine seen from above, Fig. 17 the cutting machine seen from the side,

Fig. 18 seen from the front, and

Fig. 19, 20 a modification of the cutting machine.

The parts sketched in Fig. 1 represent a production line for reinforced, strip-shaped rubber layers - tire starting material - and include the following machine parts:

Two coil stands 1 for each holding about 30 coils. The coil stand 1 are laterally displaceable in order to be able to be moved into the loading position or the active position. The mandrels of the coils do not have to be equipped with brakes.

A heating and guiding device 2 is used to bring the reinforcing material (steel wires, strands, fibers, threads) to the required temperature and to supply it to the next unit.

An extruder 3 has a crosshead through which the reinforcing material runs and is crosslinked and encased with rubber. The rubber is fed to the extruder 3 in the form of cold strips, as indicated in FIG. 2. The extruder can have a diameter of 60 to 100 mm and work with a belt extrusion speed of up to 60 m / min.

An intermediate store 4 serves to compensate for synchronism fluctuations between the extruder 3 and the winding machine 5 to be described below. The capaci ity of the buffer memory 4 should be large enough to be able to stop the winding machine 5 briefly.

The winding machine 5 guides the rubber band along a screw and presses the adjacent edges with one another, so that a rubber tube with helically inserted reinforcing materials is formed, as will be described in more detail below.

A buffer 6 receives manufactured rubber pipe pieces so that the operational sequence can proceed as steadily as possible.

A cutting machine 7 is used to cut the pipe sections in the axial direction of the pipe or according to a helix, in order to arrive at a rectangular or diamond-shaped rubber mat, as is shown at the next station.

An air cushion table 8 facilitates the handling of the rubber mats produced during further processing on a cutting table 9 , which is used to split the rubber mats into individual strips of material.

In FIG. 2, these individual processes are presented with explain the observations, but in a simplified embodiment of the plant.

FIGS. 3 to 12 show a winding machine 5 to the light generated in the extruder 3 rubber belt 10. The winding machine 5 has a winding section 11 and a storage section or support device 12 .

The winding section 11 contains a lining 13 which is held in a cantilever manner on a stand 14 and consists of a series of rollers 15 , deflection rollers 16 and endless belts 17 , 18 , 19 which are connected via a belt drive 36-38 ( FIG. 4) and Shafts 20 ( Fig. 9) are driven. Some rollers 15 run freely on axes 21 (FIGS. 10 , 12 ). The axes / shafts 20/21 are preferably inclined by an angle β = 1 ° to 1 ° 30 ′ with respect to the horizontal or the machine axis 24 falling by the angle α. The rollers 15 are arranged distributed along a pitch circle 23 , and the axes or shafts 20 , 21 extend at an angle 90 ° - β on the plane of the pitch circle 23 . The chuck 13 thus represents an approximately cylindrical cage, especially since the ends of the axes or shafts 20 , 21 can be connected to one another by means of an exchangeable support ring 22 , which can serve as a knife guide.

The endless belt 17 is guided along a screw gear, the pitch being bridged by a loop l 7 a , which runs over the deflection and tension roller 16 and thus returns the belt from the end of the screw thread to the beginning of the screw thread. The belt 17 can also extend around a plurality of screw turns, after which the loop l 7 a bridges a corresponding number of pitches. The inclination angle β is chosen so that the belt 17 runs approximately perpendicularly on the rollers 15 , so that there is no fear of lateral displacement and one-sided wear. However, the accuracy of running along a helical line can also be enforced by keyways 25 ( FIG. 11), which are provided on the surface of the rollers 15 and cooperate with corresponding keys 27 of the belts 17 , 18 , 19 . As already expressed, each belt 17 , 18 , 19 covers at least one screw turn and must therefore be returned by at least one pitch in the tension loop 17 a , 18 a , 19 a by this amount. This means that the deflection roll 16 must be inclined relative to the machine axis 24 , as can best be seen from FIG. 8.

The pitch circle diameter 23 can be changed. For this purpose, the shafts or axles 20 , 21 are mounted radially displaceably, and for this purpose foot plates 30 are seen which engage in radial slots 31 of a holding plate 33 fastened to the stand 14 and can be clamped there. Other fastening structures are also conceivable. When the pitch circle diameter 23 is changed, the circumferential length of the belts 17 , 18 , 19 on the rollers 15 also changes , which is why the loop lengths 17 a , 18 a , 19 a are to be changed, which is achieved by a corresponding adjustment of the deflection and tensioning roller 16 along one Slot 32 takes place in the holding plate 33 .

In order to change the pitch, the rollers 15 can be adjusted along their axis or shaft 20 , 21 , and for this purpose each roller 15 has a cone clamping ring 35 (FIGS . 9, 10). The cone clamping ring 35 can be released, after which the roller 15 is displaceable and thus adjustable along the axis or shaft 20 , 21 , while the set position is maintained after tightening the clamping ring 35 . As already expressed, the rollers 15 must be arranged along a helix, as can be seen in a development in FIG. 12 ( β = pitch of the helix).

An air-cooled guide roller 40 ( FIG. 6) is provided for the correct insertion of the rubber band 10 onto the chuck 13 . The rubber band 10 is carried along by the first belt 17 , the edges of the still warm rubber band 10 approaching each other and being pressed against one another after passage of a screw turn. Pressure rollers 41 , 42 that can be moved pneumatically against one another ensure good closure of the butt joint and smoothing of the seam surfaces. This creates a rubber tube 50 provided with reinforcing inserts, which grows into the storage section 12 of the winding machine 5 and can be separated from the pipe sections 51 .

A pneumatically operated knife 43 is therefore provided in the winding section 11 of the machine and can be moved into the rubber tube 50 by a pneumatic drive 44 . When the knife 43 is displaced along the machine axis at the production speed of the rubber tube 50 , the end of the cut hits the beginning of the cut, and individual tube pieces 51 are separated from the rubber tube 50 . This procedure, however, was generally not feasible because of the reinforcement, since these cannot be cut at an angle. (The knife 43 would slide off steel wires.) In such cases, the knife 43 remains stationary relative to the longitudinal axis of the machine and therefore produces a helical cut, so that pieces of pipe can only be cut off preparatively and are still connected to one another with a web corresponding to the width of the rubber band 10 . This web must then be cut transversely, ie in the longitudinal axis of the machine. The winding machine can be stopped briefly for this purpose. However, it is also possible to use the support ring 22 at the end of the winding section 11 as a guide for a rotating knife which is carried along at the speed of the rubber band 10 or the rotating speed of the rubber tube 50 produced and can cut the web transversely.

The rubber tube 50 is supported in the storage section 12 between trough-shaped support rollers 45 . In order to relieve the pressure on the pipe produced, the machine axis 46 can be arranged inclined by a small angle α relative to the horizontal. In the storage area 12 , an ejector 47 is also provided, which can be actuated pneumatically and lifts the generated and separated rubber tube 51 out of the trough formed by the rollers 45 , as indicated in FIG. 5.

FIGS. 13 and 14 show further possibilities for the arrangement of the rollers 15, the guide rollers 16 and the belts 17, 18, 19. By providing several storage loops 17 a , 17 b , 17 c , 17 d , the variability of the diameter of the pitch circle and thus of the tube diameter of the rubber tube produced is more pronounced. The deflection rollers 16 can be tensioned by rotating their support 26 ; but it is also possible to carry out the tensioning along a slot guide.

In Fig. 15 it is indicated what should happen to the pipe section 51 generated. A rotating knife 70 is aligned so that the knife plane goes through the tube axis 55 , and the knife is moved along a jacket line 58 , so that the tube 51 is slit open. The separated tube results in a rectangular rubber mat or rubber layer 52nd If the knife 70 is placed at an angle to the tube axis 55 and a screw turn 54 is moved on the tube jacket, a diamond-shaped rubber mat or layer 53 is formed. The rubber mats 52 and 53 can be divided into smaller strips 56 or 57 by further cuts, such as it is also indicated in Fig. 1 at 9.

The cutting machine 7 for slitting or cutting the pipe pieces 51 is shown in FIGS. 16 to 18. A trough-shaped frame has side cheeks 71 , 72 , of which at least one ( 72 ) can be pivoted away into a horizontal position 72 'in order to be able to accommodate the pipe section 51 more conveniently. The frame contains a plurality of rod-like rollers 73 to 77 , around which a row of belts 78 arranged parallel to one another is guided and which can be driven by means of the roller 73 . The roller 73 is simultaneously designed as a tension roller and arranged at the end of a rocker 79 , on which a drive motor 80 with gear 81 is seated. Between the rollers 74 and 75 , the bands 78 form a loop 78 ', between which the pipe section 51 is taken up and can be rotated if necessary.

A guide rail 82 extends on the upper side of the frame, along which a carriage 83 can be moved and can be driven via a cable loop 84 and an associated motor with gear 85 . The height of the guide rail 82 can be adjusted 86 by means of spindle drives. A knife drive 87 with a motor 88 for driving the knife 70 already mentioned hangs on the underside of the carriage 83 . By a slide device 89 on the underside of the carriage 83 , the cutting plane of the knife 70 can be rotated about a vertical axis, so that one can cut with the knife both parallel to the machine axis and at an angle to it. The latter is done in coordination with the Umlaufgeschwin speed of the band 78 and thus the speed of rotation of the pipe section 51 in such a way that the helical cut 54 ( FIG. 15) is cut cleanly.

FIGS. 19 and 20 show a modified cutting machine for separating the tube homes 51. The machine frame is designed as a low box, on the top of which two movable cheeks 61 , 62 are provided to form a trough. The cheeks 61 , 62 each consist of a swivel frame with a support device, the shape of which is adapted to the curvature of the pipe sections 51 .

Axes or shafts 63 , 64 extend on the upper side of the cheek 61 and shafts or shafts 65 , 66 extend on the cheek 62 . The cheeks can be pivoted about the axes or shafts 63 and 66 , for example by means of an associated pneumatic cylinder 67 , so that different pivot positions 61 ', 62 ' can be adopted to adapt to the diameter of the respective tube 51 . The shaft 63 carries pulleys 93 , the axis 64 pulleys 94 , the axis 65 pulleys 95 and the shaft 66 pulleys 96 . About the belt pulleys 93 and 94 and the pulleys 95 and 96 run belts 68 , respectively, which support the pipe section 51 laterally and, if necessary, rotate them. The shafts 63 and 66 are connected to one another via a belt drive 69 in order to be able to rotate synchronously. A motor 90 with gear 91 is provided to drive the two shafts 63 and 66 in one direction or the other. The gear 91 also drives a further gear 92 , which is provided for driving a spindle 97 which extends along the machine parallel to a guide rail 102 . On this rail 102 , a carriage 103 is guided on the upper side of which a knife drive 98 is pivotally mounted, so that the plane of the knife 70 can be inclined relative to the tube axis 55 .

The gear 92 is adjustable in terms of the ratio between the input and output speeds, in order to be able to drive different pitches of the screw 54 ( FIG. 15) by adjusting the speed of the spindle 97 relative to the speed of the shafts 63 and 66 .

Another motor 100 with gear 101 serves to independently drive the shafts 63 and 66 and thus the belts 68 to convey the rubber mat 52 or 53 produced in each case onto the air cushion table 8 .

In a further modification of the invention, the cutting machine can be integrated in the storage area of the winding machine, as indicated in FIG. 2. Such a production line is not as flexible as the device described above.

The operation of the system is as follows: Reinforcing material, for example steel wire strands, are drawn off from the bobbin stand 1 and brought to a predetermined temperature in the device 2 in order to be fed to the crosshead of the extruder 3 . Strips of raw rubber mixture are fed to the extruder 3 and brought there to the necessary temperature so that the steel wire strands are properly encased in the crosshead and the rubber band 10 is formed, which is fed to the winder 5 for further processing. In order to reduce the stickiness, a cooler can be connected upstream of the intermediate store or compensator 4 . The winder guides the rubber band 10 along a screw path, the pitch of which speaks the minimum width of the rubber band 10 ent. One screw turn of the rubber band after the other combines to form the tube 50 , which accordingly grows from the winding area 11 into the storage area 12 . As soon as the desired tube length is reached, the knife 43 extends and produces a cut that runs parallel to the rubber band 10 in which the tube 50 is made. The separated pipe section 51 is then connected to the pipe 50 in the winding area via a web which has to be cut transversely. You can do this in a short downtime of the winding machine 5 , and in this case the buffer 4 must have the appropriate capacity to accommodate the rubber band 10 continuously supplied by the extruder 3 in the meantime. But it is also possible to cut the above-mentioned web during the run of the winder 5 when the tube 5 generated from the winding section 11 passes into the storage section 12 . In the storage section 12 , the severed pipe section 51 can be cut lengthways; for reasons of greater flexibility of the system, it is preferred, however, to eject the pipe section 51 produced and to convey it into a separate cutting machine 7 . Depending on the desired end product, the pipe section 51 is cut parallel to its surface lines or along a helical line 54 , so that either rectangular mats 52 or diamond-shaped mats 53 are obtained. If required, these can be cut into further strips 56 or 57 in a conventional machine 9 .

The method according to the invention has the particular advantage that the still sticky rubber strip 10 is assembled according to a simple principle, so that faults are less to be feared at this point. The manufactured product shows flawless welding edges, because the band 10 is well pressed together with its edges and the resulting pressing beads can be smoothed out well. Finally, the corrugations of the edges of the mats produced can be avoided because the unsupported length of the steel wires or strands can be kept small during the cutting process in the cutting machine 7 , so that the strains of the not yet vulcanized rubber remain below the limit of the permanent deformation, can still regress. (In the case of sensitive material, the surface of the pipe can be supported in the immediate vicinity of the cutting point, so that the tension of the steel wires or strands is absorbed until the pipe section is completely separated. The corrugations do not occur when the pipe section as a whole comes loose spans and merges into the flat mat shape.)

Claims (14)

1. Process for the production of tire starting material with the following measures:
Reinforcing material (steel wires, strands, fibers, threads) is coated in an extruder head ( 3 ) with unvulcanized rubber, so that a continuous band ( 10 ) is formed;
the belt ( 10 ) is guided on an endless belt device ( 13 ) along a screw path and the adjoining belt edges are connected to one another, so that a material tube ( 50 ) is formed which grows beyond the area of the belt device ( 13 ) and from which again and again a piece of pipe ( 51 ) of the desired length is cut off;
The respectively separated pipe section ( 51 ) is so far away from the belt device ( 13 ) that space is created for the renewable pipe;
the successively produced pipe sections ( 51 ) are cut open in order to obtain reinforced rubber layers ( 52 , 53 );
these rubber layers ( 52 , 53 ) are further processed to the tire base material. 2. The method according to claim 1, characterized in that the adjacent band edges be butted together, one pressing and smoothing of the edge areas takes place on both sides.   3. The method according to claim 1 or 2, characterized in that the pipe pieces approximately perpendicular to the reinforcing material - approximately parallel to the Rohrach se ( 55 ) - are cut open, while at the same time a lateral support (at 74, 75; 93, 96 ). 4. The method according to claim 1 or 2, characterized in that the pipe sections ( 51 ) at an angle to the reinforcing material - along a helix ( 54 ) - are cut open, while at the same time a lateral support (at 74, 75; 93, 96 ) . 5. winding machine for performing the method according to claim 1 or 2, characterized by the following features:
a number of rollers ( 15 ) is arranged on a circular circumference ( 23 ) and is arranged with its axes ( 20 , 21 ) rotatably in a machine frame ( 14 );
the rollers ( 15 ) are provided with guide devices ( 25 ) for one or more belts ( 17 , 18 , 19 ) of the Riemeneinrich device ( 13 ) to this or this along a helix on the circumference of the rollers ( 15 ) enveloping cylinder to lead;
at least one further deflection roller ( 16 ) is provided in the interior of the cylinder in order to tension the belt or belts ( 17 , 18 , 19 ) and to return them from the end of the associated part of the helical line to the beginning of the associated part of the helical line;
at least one roller ( 15 ) can be driven in order to drive the belt or belts ( 17 , 18 , 19 ) along the helical path and the inner return path. 6. Winding machine according to claim 5, characterized in that the axes ( 20, 21 ) of the rollers ( 15 ) with respect to the axis ( 24 ) of the cylinder are inclined by the pitch angle ( β ) of the helix. 7. Winding machine according to claim 5 or 6, characterized in that the guide devices consist of wedge grooves ( 25 ) on the circumference of the rollers ( 15 ) which cooperate with wedge formations ( 27 ) on the underside of the belts ( 17, 18, 19 ). 8. Winding machine according to claims 5 to 7, characterized in that a plurality of belts ( 17 , 18 , 19 ) are arranged distributed along the axis ( 24 ) of the cylinder. 9. Winding machine according to claims 5 to 8, characterized in that the axes ( 20 , 21 ) of the rollers ( 15 ) are adjustable in the radial direction of the cylinder in order to be brought to different circular diameters ( 23 ). 10. Winding machine according to one of claims 5 to 9, characterized in that in the axial direction ( 24 ) subsequent to the rollers ( 15 ) on the machine frame, a supporting device ( 12 ) for the tube ( 50 , 51 ) produced is seen easily contains a series of support rollers ( 45 ). 11. Winding machine according to claim 10, characterized in that an ejector ( 47 ) for lifting the separated pipe section ( 51 ) from the support device ( 12 ) and forwarding to a cutting machine ( 7 ) or an intermediate store ( 6 ) is provided. 12. Cutting machine for performing the method according to claim 3 or 4 with the following features:
a frame ( 60 ) has lateral cheeks ( 61 , 62 ; 71 , 72 ), which are provided with support and rotating devices for a pipe section ( 51 ) that has been taken up, in order to close the pipe section ( 51 ) near the cutting point ( 54 ; 58 ) to support;
at least one cheek ( 61 , 62 ; 72 ) is designed to be pivotable;
a cutting knife ( 70 ) can be adjusted with respect to its cutting plane and can be moved along the frame ( 60 ). 13. Cutting machine according to claim 12, characterized in that the supporting and rotating devices on rollers ( 73-77 ) or pulleys ( 94-96 ) contain belts ( 68 , 78 ) containing the pipe section ( 51 ) on part of the circumference surround. 14. Cutting machine according to claim 12 or 13, characterized in that the cutting knife ( 70 ) is arranged on a carriage ( 103 ) which can be driven via gear devices ( 91 , 92 ) which also for driving the supporting and rotating device ( 78 ) are provided.