FIELD o-f the INVENTION The present invention concerns a process for mechanical breaking o-f used tyre casings as well as the process equipment, which can be industrially applied at processing and secondary utilization o-f the rubber and metal recovered from them.

PRIOR ART There are well-known different technical solutions including technique and equipment based on different ways and means for breaking of worn out tyre casings. Each of those technical methods has its own advantages and di advantages due to its concept. For example, well known is the method /DE 2 553 539/ for mechanical breaking of worn out tyre casings, according to which the tyre is cut off at a certain place along its radius, than it is spread out while at the same time the beads are cut off; then follows a feeding of the beads separately from the other opened and flatten down part. The beads are further cut into smaller pieces by an additional cutting device and the obtained pieces are gathered in a hopper different from that for the pieces (shavings) obtained from the cutting of the flatten down tyre with the main cutting tools.

The equipment /DE 2 553 539 / for this process

comprises: a stand for fastening and winding up the worn out tyre with a tool radially guided to the tyre for cutting along the radius; an assembly consisting of a series of rolls for spreading out the cut out tyre passing through them and fed to the next system of upper and bottom rolls with bead cutting tools and an additional cutting descending device for their breaking up to small pieces; as well as an assembly for further horizontal feeding of the flatten down tyre without the beads to the main cutting device which in fact is a rotary milling tool. The feeding is in a vertical direction towards the rotating axis of the milling tool. Keeping the tyre flattened down to the milling tool is done by a system of opposite rolls (upper and bottom) hydraulically driven. At the end of the low plane is fastened a counter tool against which a set of milling disks is arranged with two sizes of the working diameter in a sequence. Each milling disc is phase displaced toward the next one with regards of the cutting teeth. The described technique and equipment are not very efficient at tyre flattening down, as its metal cord makes it very hard and the rolls can't straighten it enough in the part fed to the milling tool. Beside that it is not ensured a satisfactory separation of metal and rubber shavings after the final tyre cutting, because only the armoured beads are cut off for particular milling, while the tyre shoe with the metal cord in it

is cut off together with the worn out tyre protector and rubber walls by disc-type milling cutters. This creates certain difficulties at further processing of the secondary material for reusage. Besides that, as the front edges of the milling teeth are parallel to the disc axis, an impact ioading happenes during the cutting process, which causes a high irregularity of the milling process. Furthermore the cutting tools arB made of hard alloy and they cut the metal cord with great difficulty. At the end, there is a considerable gap between the counter tool and the cutting tools, which allows the metal cord to be led out.

Another equipment /DE patent 3 923 971/ for cutting off worn out tyres is also well- known, at which there is a magnetic separator for the metal pieces located after the crusher over a belt conveyor for carrying out the tyre pieces. This equipment comprises a cooling tunnel and hammer crusher consequently installed providing a preliminary deep cooling upto - 70o C of the entire or cut off tyre for its satisfactory crushing in the hammer crusher.

The disadvantages of this equipment is of maintaining a cooling installation which makes the process very complicated and expensive as a result of high power consumption. Beside that the capability of crushing the armoured tyre parts in small pieces is very disputable. There are equipments /SU certificates 737 235 and 937

225/ with driven and driving rolls for tyre sheeting as the tyre is pulled on over one of the rolls. These equipments are provided with a cutting saw or disk-type milling cutter for tyre slitting in strips, which then are fed in a chute to the face milling tool.

The disadvantages of those installations are in their low productivity and the unreliability of the cutting since the metal cord is hard and resilient and it is very difficult to be cut off with tool of high-speed steel and tool steel. Beside that the cord small diameter also clutches with the teeth of the slitting saw or the disk-type milling tool and causes their breaking. In addition to that, the face milling of spring wire which is the nature of the metal cord is accompanied with elastic deformations and cutting difficulties.

Also a synchronization is not foreseen between feeding of the strip with tooth number and revolution number of the milling machine or the rotating tool, therefore a controlled cutting and high productivity is impossible to be achieved.

BRIEF DESCRIPTION of the INVENTION The invention task is to reduce to minimum the above mentioned disadvantages and to create a technique and equipment ensuring effective breaking-up of the worn out tyre casings and separation in uppermost degree of metal and rubber pieces.

Another aim of the invention is to increase the productivity at higher operational reliability and equipment precision.

For that purpose it is suggested a mechanical cutting of the worn out tyre casings and for that the process requires a strict sequence of operations including the initial removal of the remaining tyre protector followed by simultaneous cutting of the tyre to ringshaped parts from the armoured tyre shoe, two toroidal rings from the side armoured beads and two approx flat disk-shaped washers from the tyre walls. Generally speaking the ring-shaped parts are further cut out to two semicircles each along its diameter and then followed by final cutting out and separation to metal and rubber shavings. The initial removal of the remaining protector is made by a method and equipment described in an earlier BG patent application Reg. No.50716 by the same applicant and inventor. For that reason this operation is mentioned here only as a stage of the whole process for the final cutting off to small pieces of the worn out tyres. At that stage the whole automobile wheel (tyre and rim) is inflated in order the tyre to be strained and the cutting efforts applied to ensure the removal of the remaining worn out protector. So the whole wheel is fixed by rotation and the cutting and removal of the protector is made during its rotation within 0,5 - 0,6 of the revolution by

stretching cutting tools from at least two opposite places along the perimeter of tyre protector. The tools are making the cutting off on the whole protector profile at synchronization between their motions and tyre rotation.

The equipment used for that purpose comprises a fastening device, inflator, wind up device and an assembly for radial motion of the feeding slides with the cutting tools and the motors. A special feature of the present invention is the tyre's further processing until final cutting to small pieces and the separation of the metal and rubber shavings.

For that reason, according to this technique, immediately after the above described operation is provided a simultaneous cutting of the armoured tyre parts which slits the tyre to five parts: two toroidal rings of tyre armoured beads, a ring from armoured tyre shoe and two approx. Flat disk- like washers from tyre rubber walls. This cutting off is made on two sides for a tyre revolution after a preliminary sidewards motion of the cutting tools in parallel to tyre rotating axis until they plunged into. Next stage of the process is the cutting out of the ring-shaped parts in two along their diameter and their transport for final cutting and separation.

The equipment necessary for the respective operations

of the described technique beside the unit for removal the remaining protector according to the Bulgarian patent application Reg. o.50716 are given in the following interacting and consequence arrangement on process line and in compliance with their technical performace, as follows:

After the protector removal device, a device for simultaneous cutting and disintegration of the tyre casing to 5 ring-shaped elements follows including positioning and holding the tyre in working position, wind up mechanism and equipment for cutting and disintegration.

The device for positioning and holding in working position consists of a driven roll on which the tyre is pulled on for cutting. The roll is borne on an arm fixed to a movable horizontal table. The table makes two perpendicular reciprocating motions, one in vertical and the other in horizontal direction with respect to the direction of the driven rolls axis. The device for rotating the driven roll with the tyre on it consists of a drive roll with hydraulic motor fastened to the bottom side of a saddle over the driven roll and sliding on the guides of a static foundation frame. The saddle is vertically moved by a hydraulic motor fastened to the frame vertically.

The equipment for tyre cutting off includes two carriages on both sides of the driven roll under the

drive roll and making horizontal and reciprocal motions by means of horizontally mounted carriage hydraulic cylinders. The carriages are provided with two (upper and bottom) guilotine tools mounted in parallel, while symmetrically between them are bearing at least at one spring roll for pressing tyre walls to the driven roll crown.

The next on-line device is designed for cutting the ring-shaped elements in two semicircles and it includes positioners and cutting tools. The positioners have four radial travelling bearings positioned in symmetry on two perpendicularly cross axes in a same horizontal plane. The cutting device consists of two guillotine-tyre tools, each mounted in a holder and guided to a casing. They are fastened on the same horizontal plane and are situated outer of the oposite movable bearings with regards the ring cutting along the diameter. The static end of the relevant hydraulic cylinder is fasten to the low side of the horizontal plane and by means of a hinge-lever connection drives the guillotine tool in horizontal radial direction for cutting the ring-shaped elements in two semicircles.

At last for the final processing stage of the cut off worn out tyre parts is mounted a device for final cutting and separation of metal and rubber shavings. The device consists of two-parts casing (a body and a lid) with connected to it changeable chute in accordance

with the shape and number of the fed semicircles, with changeable in accordance with the profile upper and bottom rolls arranged in opposite and with a fixed disk-type cutting tool inside the casing on a horizontal rotating axis.

So described this device is similar to the device for the same purpose used earlier by the same inventor under BG patent application Reg. o.50830 with that difference that in the former device instead of profile changeable chute with the respective pairs of rolls is used a permanent belt conveyor. In the present case, this type of device has gone further development of its desigh leading to new qualitative characteristics improving considerably its operational performance. The development is made in setting and adding new technical means and features: the mentioned disk-type cutting tool is used with normally arranged cutting teeth, while the new type represents a series of several stringed up disks and each disk is provided with the necessary number of cutting teeth and they are foreseen to be fastened to their peripheral surface in sequence but alternatively inclined to the disk central rotating axis, that means at equal angle with alternatively changing sign towards the axis. Besides that, each of the disks is mounted with phase displacement to the next disk equal to 1/2 step. A counter—tool is provided fastened in the main body at the point of connecting the

changeable chute so that its cutting edge lies in the horizontal plane of the rotating axis of the cutting disk-type tools. The distance between the counter-tool and its oposite edge of the disk-type cutting machine is foreseen also, to be adjusted during their rotation with the help of horizontal motion of the counter-tool. The purpose for that is to be ensured such a small gap, which to be less than the diameter of the cut single metal wire from the tyre metal cord. In such a way optimum conditions are provided for cutting the metal wires and also their frequent bending is avoided which exists with other similar devices. Of extreme importance are the alternatively inclined tools and their phase displacement as this creates conditions for simulation of guillotine type cutting, which secures uniform and impactless cutting, which on its turn has very favourable effect on the quality of the cutting process, obtaining as far as possible fine shavings. Of considerable importance is the fact, that the cutting tools are of hard alloy with titanium-nitride coating that increases the cutting reliability and tool-life. Besides that the feeding speed of the armoured semicircles is foreseen to be in compliance with the number of tools and rev/min in order to be ensured maximum cutting productivity.

For the separation of metal and rubber shavings a magnetic separator and a belt conveyor under it are

provided in the low part of the casing under the disk-typs cutting tools for carrying the separated pieces out of the casing.

BRIEF DESCRIPTION of the FIGURES On the undermentioned drawings is given an example of the technique and the plant for mechanical cutting of worn out tyres and separation of the metal cord, subject of the invention, for better clarification of the concept, as follows: - Fig.l shows a general plan of the plant for mechanical cutting of worn out tyres and for separation of metal and rubber pieces;

- Fig.2 shows a principle scheme of the initial rotating cutting and protector removal from the tyre shoe of useless tyres, which is a particular assembly of the plant indicated under pos.A on Fig.l;

- Fig.3 is a principle scheme of next exactly defined tyre cutting through cutting the armoured shoe and beads, separating the wall too. This device is indicated under pos.B on Fig.l;

- Fig.4 is a principle scheme of a device for two-side guillotine type cutting in two the just cut armoured ring-shaped parts of shoe and beads and of tyre walls, indicated under pos.C - 6 - on Fig.l; - Fig.5 is a scheme of the device for final cutting of the semicircles by means of controlled guillotine-type cutting, indicated under pos.D on Fig.l;

- Fig.6 is a scheme for the arrangement of the cutting tools of the device on Fig.5 and more especially that of their cutting edges.

DETAILED DESCRIPTION of the INVENTION So on Fig.l is shown in consequence the arrangement of the different devices according to the performance of the special operations.

The tyre (1) is put in initial working position, as the consequent travel and passing of the tyre as well as of its cut parts through the different devices can be made by an automatic control system, but this is not the subject of this application and for that reason is not indicated on the drawing.

Each of the devices is able to operate separately, but in such case the intermediate product should be fed manually to the next processing device for the respective operation.

Therefore, according to Fig.l the worn out tyre (1) in pos.A within 0,5 - 0,6 of its revolution is processed for removing the remaining protector; in pos.B for one tyre revolution are cut si ultaneously its armoured shoe and beads together with both walls; in pos.C simultaneously in two radial opposite points are cut with guillotine-type tools the armoured shoe and bead rings in two semicircles; in pos.D the semicircles are fed through configurated feeding devices in compliance with the shape of the semicircle processed at the moment

and representing an element of the final cutting device to the cutting tool. In that appliance in a specific and preferred way are arranged the hard alloy tools for guillotine-type cutting of the metal cord and the rubber towards the axis of the disk-type cutting machine, that is needed for conversion of the pieces into shavings which then are separated in the same device and carried out separately.

According to Fig.2, the device for removal of worn out tyre protector as a special assembly of the plant includes gear 5 for fixing, inflating and rotating of automobile wheel with worn out tyre (1). This gear is driven by motor 6 fastened to a body 4 together with gears B and B' for radial move of the feeding tables 3 and 3', supporting profile round broaches 2 and 2' driven by motors 7 and 7' for protector cutting within 0,5 - 0,6 tyre revolution. Also a shaving collector 9 is intended representing a belt conveyor mounted in the lower part of the device under the described mechanism. In details, the technical concept and operation of that device are described in the Bulgarian patent application under Reg.No.50716 of the same inventor and applicant, protecting the latter device as a separate technical unit. The next stage of the processing of worn out tyre (1) includes the simultaneous cutting out of its armoured parts, i.e. the tyre shoe and beads. With their

cutting the tyre is desintegrated into 5 parts: two armoured bead toroidal rings, an armoured cylindric ring from tyre shoe and two rubber disk-like washers before the cutting of tyre side walls. The device making these operations is shown on Fig.3 and is indicated on Fig.l under pos.B. It consists of: a positioner and holder in working position of the tyre (1), driving gear (for rotation) and tools for its disk cutting into rings. The means for positioning and fixing in working position includes a driven rool (11) borne on an arm (13) fastened to horizontal table (12) with two perpendicular reciprocating motions, one in vertical, the other in horizontal direction with respect to that of the driven rool (11) axis. The table (12) is mobile mounted on the device base (10).

The driven rool (11) is changeable, as a series of several rools with different sizes (i.e. 3 series) is provided, covering the different sizes of the tyres to pull them for cutting in ring-shaped parts.

The equipment for the rotation of the tyre on the driven roll includes: a driven roll (17) borne on a spindle driven by a hydraulic motor (16); a saddle (18a), to the bottom side of which is fastened the drive roll (17) and hydraulic motor (16) and the saddle (18a) is slidingly mounted on the guides (18) of a frame (21) fixed to the foundation while for its vertical and

reciprocating motion on guides (IB) is provided a second vertically mounted hydraulic motor (12).

The saddle (18a) with the assembly of the driving roll (17) and hydraulic motor (16) are settled above the driven roll (11), so at their vertical motion on guides (18) to be ensured a possibility for precise symmetric surface contact between the driven roll (11) with the tyre on it and the drive roll (17).

The means for tyre cutting, i.e. its disintegration to three ring- shaped elements and two disk-like washers include two carriages (15) located under the driving roll (17) on both sides of its vertical symmetric axis, appearing as long symmetric axis of the vertically mounted hydraulic cylinder (19), respectively on both sides of driven roll (11), which carriages (15) are foreseen to make horizontal reciprocating motions by means of two horizontally mounted support hydraulic cylinders (14). The horizontal movement of carriage (15) is provided on horizontal guides on frame (21), the same frame is bearing also the horizontal carriage cylinders (14). Two cutting tools (20) are mounted on each of the carriages (15), an upper tool for cutting one side of tyre shoe ring and the bottom roll for cutting the armoured bead from its side. Symmetrically between two tools (20) are mounted spring rolls (20a) borne on their own axes in a way to press the tyre walls to the driving roll crown (11).

This device operates in the following way: After the removal of the remaining protector described in the Bulgarian application for patent Reg. o.50716 and before pulling the tyre on to the driven roll (11), the horizontal carriages (15) are drawn out of the roll (11) and the saddle (18a) by the driving roll (17) while hydraulic motor (16) is in its upper position on guides (18). After the tyre has been pulled on the driven roll (11) and after its fixing on its stand (13) in the required working position, a vertical lowering of the saddle (18a) follows with drive roll (17) and hydraulic motor (16) until the drive roll (17) is pressed to the tyre shoe in such a degree that at rotation of drive roll (17) by the hydraulic motor (16) the friction forces arisen between the roll, tyre shoe and the driven roll (11) cause a turn of driven roll (11) and therefore a move of tyre shoe between both rolls and overcoming the cutting resistance of the side tools (20) plunged into the tyre. The next moment is the forward movement of the carriages (15) driven by the horizontally mounted cylinders (14) to the tyre and the plunging into it of tools (20) in the upper parts of the tyre immediately under the shoe and in the lower parts immediately above the armoured beads and especially to the complete pressing of spring rolls (20a) to tyre rubber walls causing deformation on the pressing point of the tyre to

driven roll (11) crown.

In that way the tyre is exactly positioned and fixed. Next motion is the device working motion of ring-shaped cutting. For that purpose the hydraulic motor (16) is switched on and it drives the connected to it drive roll (17). Due to friction forces arisen by the operation of the vertical hydraulic cylinder (19) which provides the vertical lowering of saddle (18a) with the drive roll (17) and hydraulic motor (16) and the required pressing of drive roll (17) the later turns the driven roll (11) and in that way carries away and turns the tyre pressed between them, overcoming the cutting efforts of the plunged in it support tools (20a). As a result it is provided for a tyre revolutoin a complete cutting of its shoe and beads and that means disintegration of the tyre to an armoured cylindric shoe ring, two armoured toroidal bead rings and two rubber walls with the shape of disk washers. Then follows a switch off of hydraulic motor (16), drawing up the saddle (18a) with the assembly of driving roll (17) and hydraulic motor (16) by the vertical hydraulic cylinder (19) and aside of carriages (15) by the horizontal hydraulic cylinders (14) for releasing the driven roll (11) and taking off of the cut ring-shaped/disk-like parts followed by positioning of a new tyre for process recycling.

The further operation foresees the cutting of the obtained parts to semicircles and half disks in order to

proceed easier with their further cutting. The device making this operation, indicated under pos.C on Fig.l, includes the following positioning and cutting means: The positioning means are built on four supporting elements (22) arranged in symmetry on two perpendicularly crossing central axes laying in the same horizontal plane of base (29) as their motion on the axes direction is adjusted by means of the helical gear (28) fastened to this base (29). On the bottom side of this horizontal plane just under the two opposite supports (22) is fastened the immobile end of a hydraulic cylinder (25) receiving oil under pressure from the hydraulic unit (26). The hydraulic cylinder piston (25) is connected in sequence by a system of two levers, one under pos. 7 is of first order and the second under pos.27a is of second order with a holder (23) of a guillotine tool (23a) while the holder (23) is in a casing (24) and is also fastened on the horizontal plane of base (29) outside against the two opposite bearings (22) with their respective hydraulic cylinders (25). Therefore the cutting tools are arranged in two groups opposite to each other, but along one and the same central axis.

This device operates in the following way: The cut ring or disk-like washers (1') of the tyre are pulled on carriages (22), which are gathered to the center by the helical gear with a handle (28). At that

time the guillotine-type tools (23a) are in non- working position and are almost hidden in guide (24). In the operation given as an example on Fig.4 is foreseen the cutting of the cylindric ring of tyre shoe in two parts indicated under pos. 1'.

After the putting of the ring, it is tightened through opening of carriages (22), i.e. their moving out of the center and the following turn of hydraulic cylinders (25) under the horizontal plane of base (29). The latter, through its hinge connection system of two levers (27) and (27a), puts into motion the holders of both opposite guillotine tools (23a) on their guides towards the tightened ring 1' and they press and cut it in two equal halves. The latter are dropped out of the carriages (22) after which the tools are gathered and the carriages (22) are adjusted by helical gear (28) for feeding and stretching the next type and size of cut ring or disk.

Now the cut semicircles and semi-disks are fed for final cutting and separation of metal and rubber pieces. This is made in the next device, shown on Fig.5. It includes a two parts casing - a main body (31) and a lid

(32) to which casing is connected a changeable chute

(33) in accordance with the profile, provided with changeable profile opposite arranged upper and lower rolls (34), as inside of the casing is fixed the disk-type cutting tool (35) on a horizontal rotating

axis (30). The rotating motion of horizontal axis (30) is realized in the well known way but not indicated on the drawing. The disk-type cutting tool (35) is a set of several stringed one to another disks. Their optimum number (according experimental data) is 6 (six) at 50 mm disk width and 315 mm working diameter of the same. Each one of the disks is equipped with the required number of hard alloy edges (40) with titanium-nitride coating, fastened to their peripheral surface in sequence, alternatively inclined at equal angle (Wo), but with alternatively changing sign with respect to the central axis (30) of disks (35) . Besides that, each disk (35) is mounted with phase displacement with regards to the next disk (35), equal to 1/2 step. Also a counter tool (39) is foreseen which is fastened to the main body (31) at the point of entering the changeable chute (33) in such a way that its cutting edge lies in the horizontal plane in which lies also the horizontal axis of symmetry of the cutting disks (35), respectively axis (30).

It is foreseen the distance between the counter tool (39) and the respective opposite edge (40) of disk (35) will be adjusted during its rotation in view this gap "c" between them to be less than diameter "d" of the single metal wire of the metal cord. Above the counter tool (39) in the main body (31) is mounted a pressing roll (36) with the only purpose to press the semicircle

1' subject to cutting towards the same counter tool ⁽ 39) and in this way to secure vertical immobility of the semicircle during its cutting between the counter tool and the respective tool (40) at the rotation of disks (35).

It is necessary to be mentioned that the changeability of the transport chute (33) and profile rolls (34) is depending on the different shape of prepared for final cutting tyre's parts, namely: t o halves of armoured cylindric shoe, those of both toroidal armoured beads and those of pure rubber walls having approximately the shape of flat disk- type pulleys. In this connection three types of changeable chutes (33) and profile rolls (34) are foreseen as the width of each type chute and the profile rolls respectively is in compliance with the width and number of the simultaneously fed parts for final cutting, otherwise said of the semicircle parts. For example it is foreseen at feeding the shoe se icicles to be used a chute with a width as the show width, while the profile rolls (34) and the pressing roll (36) are to have smooth cylindric peripheral surfaces. For the cases, when toroidal or washer—like parts are fed, it is foreseen to be used such profile rolls (34) and pressing roll (36), which have cylindrical grooves on their periferal surface with sizes allowing the toroidal or washer—shaped halves to be hold between them as the

number of grooves is agreed with the prefered defined number of simultaneously fed halves for cutting.

In all cases the lower profile rolls (34) are mounted in a way to come in partially inside the shute through holes in chutes (33) made at the place of mounting those rolls in order to perform the pressing and leading of the fed parts betwec?n them and the upper profile rolls (34). The fasitening of those rolls (34) and of chute (33) is conventional on a certain static frame not shown on the drawing in order to be avoided its overcrowding. The driving of profile rolls (34) is also normal ace. to the system push-pull of front and rear group of rolls respectively and for that reason it is not a subject of any patent application and it is not mentioned in the example performance with regards to easier adoption of the new elements.

The invented device takes up all quantities intended for final cutting and gradually by adjusting the feeding speed with the profile rolls (34) and pressing the transported parts 1" with the pressing rolls (36) towards the counter tool (39) is realized their cutting in shavings, after their going between the counter tool (39) and the moving forward guillotine-type hard alloy tool (40) of the rotating disk (35). Of considerable importance is the fact that the alternatively inclined arrangement of cutting edges (40) on disk (35) and their phase displacement by 1/2 step at

mounting of each consequently stringed on the axis (30) disks (35) is ensured mar.? sensitive impactless and uniform cutting.

According to one of the preferred per ormances, the number of the cutting edges (40) and disk (35) rotating speed are in comformity with the speed of fed semicircles parts 1", so within 30 sec both halves of cutting semicircle are broken to pieces.

The broken pieces fall to the casing bottom of this final device of the plant where on different levels are mounted a magnetic separator (37) and a belt conveyor (38), the latter being mounted under separator (37). In that way the metal pieces have been caught on the magnetic separator and carried outside the casing in the already well-known way by means of a mechanical brush, which is not an object of the invention and for that reason is not shown on the drawing. On the other hand, the rubber shavings fall on the belt conveyor (38) and are carried out of the casing separately from the metal shavings.