Toothed belt and method and device for producing the same

Abstract

Device for producing a toothed belt (4) made of rubber and / or plastic, with a cylindrical tool drum (1) rotatable about its longitudinal axis (22), on which a belt body (a) toothed at least on one side with a radially inner tooth head region (b), a belt back region (c) radially outer with respect to the toothing and a tooth root region (d) arranged radially therebetween can be produced, wherein the tool drum (1) has grooves (2) aligned in the longitudinal direction on its outer peripheral surface, wherein the grooves (2) have the tooth shape of the toothing of the toothed belt (a) to be produced, with a tension cord laying unit (7) movable in the longitudinal direction of the tool drum (1), by means of which at least one main tensile strand (5) can be wound onto the tool drum (1), which acts as the main strength member and can be arranged in the tooth root area (b) and / or in the belt back area (c) of the belt body (a), characterized in that that an auxiliary tension cord laying unit (8) is arranged on the tension cord laying unit (7), by means of which at least one auxiliary tensile strand (6) can be arranged in the belt body (a), which acts as an additional strength carrier, that by means of the auxiliary tension cord laying unit (8) the auxiliary tension cord (6) can be laid around the main tension cord (5) in such a way that loops (15) can be formed with the auxiliary tension cord (6), and that by means of the auxiliary tension cord laying unit (8) the loops (15) of the auxiliary tension cord (6) can be inserted into the grooves (2) when the main tension cord (5) and the auxiliary tension cord (6) are wound onto the tool drum (1) in such a way that in the finished product the auxiliary tension cord (6) is arranged essentially in the tooth head area and is operatively connected to the main tension cord running in the belt back area or tooth root area.

Description

[0001] The invention relates to a device for producing a toothed belt made of rubber and / or plastic, with a belt body which is toothed at least on one side and which has a radially inner tooth head region, a belt back region which is radially outer with respect to the toothing and a tooth root region arranged radially therebetween, with at least one main tension cord which acts as a main strength member and is arranged in the tooth root region and / or in the belt back region following the circumferential contour of the toothed belt.

[0002] Timing belts constructed in this way, as well as methods and devices for their manufacture, are known per se. These timing belts are used as drive belts in traction drives for power transmission in machines in which no slippage may occur between the driving and driven parts. This is achieved by the annular timing belt with radially inner teeth being positively inserted into appropriately toothed pulleys. Slipping or skipping must be ruled out to prevent damage to the driving or driven machine. Compared to chain drives, timing belts are characterized by their lower weight and have the additional advantage that they do not usually have to be housed in a lubricant-filled housing, making them easier to access. In engine technology, they are used, for example, as synchronous belts or timing belts.Timing belts are exposed to diverse operating conditions and must meet stringent wear resistance and dynamic load capacity requirements to achieve a long service life. Timing belts are also required to be able to transmit ever-increasing torques.

[0003] Timing belts are typically made of rubber, such as HNBR (hydrogenated acrylonitrile butadiene rubber), or of a plastic or polymer, such as polyurethane, or of such mixtures. The timing belts are also equipped with a reinforcement. The reinforcement is a tensile strand made of one or more threads, the so-called cord. It is usually made of aramid fibers, polyethylene fibers, or polyurethane fibers and runs essentially near the radial outer side or back of the timing belt. Power is transmitted via the tensile strand of the reinforcement, but the force is introduced into the timing belt in the area of ​​its teeth, so that this tooth area is subject to particularly high mechanical stress.

[0004] A known manufacturing process for such timing belts uses a cylindrical tool drum with longitudinal grooves on its outer surface running parallel to the longitudinal axis of the tool drum. These longitudinal grooves serve to shape the teeth of a timing belt to be assembled on the tool drum. After a reinforcing fabric has been applied, the tension cord is wound onto the tool drum in a spiral, forming a tension layer. The polymer mixture or rubber mixture is then pressed from the radial outside, i.e. from the back of the timing belt to be manufactured, to the radial inside, i.e. to the tooth side of the timing belt, through the spaces between the individual threads and the turns of the spiral. This material structure is then vulcanized under pressure and heat.

[0005] Against this background, a toothed belt is known from DE 34 90 289 C2, for the production of which one or more fiber-containing polymer layers and a fiber-free cover layer are placed on a longitudinally grooved tool drum after the application of a reinforcement layer and a tensile layer, wherein the polymer layers are partially pressed through the tensile layer using pressure and heat, so that the belt teeth are essentially formed by the fiber-containing polymer layers, wherein interconnected interfaces are formed between the fiber-free cover layer and the fiber-containing polymer layers.

[0006] DE 29 44 209 B2 discloses a timing belt. For its production, a layer of fiber-blended material is first placed on a grooved drum after a fabric covering made of stretchable fabric is applied, and the material is pressed into the grooves. A tension band made of helically twisted cord threads is then wound over the layer of fiber-blended material. A layer of elastomeric material, such as a rubber sheet, is then placed on the cord, and the entire layer structure is vulcanized using a push-through process, with the layer of fiber-blended material being pushed into the tooth tip area.

[0007] EP 0 599 145 A1 discloses a timing belt for which a tensile strand is wound into a spiral on a grooved drum after a reinforcing fabric has been applied, and a polymer mixture is then pressed through this tensile layer. Before being pressed through the tensile layer, fibers from a defined length range in a defined concentration are added to the polymer mixture and the polymer mixture is processed. For this purpose, the polymer mixture is extruded, for example pressed through nozzles in an extruder and / or calendered, for example rolled in a calender, such that the added fibers run essentially parallel to the direction of the individual threads of the tensile strand. After the pressing process, the entire matrix of the timing belt, from the tooth area to the back of the belt, contains fibers in a defined volume fraction and with a defined orientation.

[0008] DE 10 2014 202 967 A1 and EP 1 580 453 A2 disclose a timing belt with an auxiliary tension member. However, the manufacturing process for such a timing belt and the necessary manufacturing equipment are not disclosed.

[0009] DE 10 2004 044 218 A1 discloses a device for producing a timing belt with an auxiliary tension member. This method does not achieve high strength in the toothed area.

[0010] The invention is based on the object of presenting a device for producing a toothed belt which has a higher strength and load-bearing capacity, particularly in its tooth area.

[0011] The solution to this problem arises from the features of the independent claims, while advantageous embodiments and further developments of the invention can be found in the respective associated subclaims.

[0012] The invention is based on the finding that, in a timing belt, a tension cord acts as a strength carrier, which determines the torque it can transmit. On the other hand, the forces to be transmitted from the timing belt, which runs on toothed pulleys, are transmitted via its teeth, which limits its load-bearing capacity. Fiber-filled rubber or polymer mixtures impede the usual radial pushing through of the material by the wound tension cords during vulcanization and cannot increase the load-bearing capacity of the timing belt to the extent that a tension cord can, which acts as a strength carrier not only in the belt back area but also in the toothing of the timing belt.

[0013] A corresponding toothed belt made of rubber and / or plastic, with a belt body toothed at least on one side, which has a radially inner tooth head region, a belt back region that is radially outer with respect to the toothing and a tooth root region arranged radially between them, with at least one main tensile strand that acts as a main strength member and is arranged in the tooth root region and / or in the belt back region following the circumferential contour of the toothed belt. At least one auxiliary tensile strand is arranged in the toothed belt, which acts as an additional strength member, wherein the auxiliary tensile strand is arranged essentially in the tooth head region, but is operatively connected to the main tensile strand.

[0014] A tensile strand or cord is a flexible fiber or thread product that is elongated in relation to its diameter and designed to absorb tensile forces.

[0015] In addition to a tensile member as a strength member, the timing belt features an auxiliary tensile member as an additional strength member. This member runs in the tooth tip area and is connected or operatively connected to the main tensile member. This provides additional strength to the timing belt, especially in the tooth area, making it more resilient overall and capable of transmitting higher torques. The additional strength member can also extend the service life of the timing belt, extending replacement intervals and reducing service costs.

[0016] The timing belt with the two differently arranged tensile cords can be made of materials that have already proven themselves in timing belt production. Accordingly, the timing belt can be made of an elastomer material, a polymer material, and / or a thermoplastic material. The main tensile cord and / or the auxiliary tensile cord can, for example, consist of a glass cord, a polyethylene cord, a polyurethane cord, and / or an aramid cord. The expert may specifically use suitable materials or combinations thereof to prioritize certain desired properties such as tensile strength, flexibility, aging resistance, acid resistance, and price-performance ratio, depending on the application and requirements.

[0017] To produce such a toothed belt, a special manufacturing process is necessary, in which a belt body with at least one tooth is formed on a cylindrical tool drum rotatable about its longitudinal axis, which belt body has a radially inner tooth head region, a belt back region radially outer with respect to the toothing and a tooth root region arranged radially therebetween, wherein the tool drum has grooves on its outer circumferential surface aligned in the longitudinal direction, wherein the grooves have the tooth shape of the toothing of the toothed belt to be produced, wherein in a vulcanization process the material of the belt body is pressed through a tension cord arrangement and formed into the grooves of the tool drum, and in which at least one main tension cord, which acts as the main strength member and is to be arranged in the tooth root region and / or in the belt back region of the belt body,is wound onto the tool drum.

[0018] At least one auxiliary tensile strand is arranged in the belt body, which acts as an additional strength member, such that by means of an auxiliary tensile strand laying unit the auxiliary tensile strand is laid around the main tensile strand in such a way that loops are formed with the auxiliary tensile strand, and that when the main tensile strand and the auxiliary tensile strand are wound onto the tool drum the loops are inserted into the grooves, so that as a result a not inconsiderable part of the length of the auxiliary tensile strand is arranged in the tooth head area.

[0019] When manufacturing the timing belt according to the aforementioned process, the auxiliary tensile cord is wrapped around the main tensile cord. Loops are formed from the auxiliary tensile cord, linking the auxiliary tensile cord to the main tensile cord. The main tensile cord, together with the auxiliary tension rod, is then wound spirally onto a tool drum with longitudinal grooves corresponding to the intended tooth shape. The loops are inserted into the grooves of the tool drum so that the auxiliary tensile cord in the finished product essentially runs in the tooth tip area, while the main tensile cord runs in the tooth root area and / or the belt back area. The tooth root area and / or the belt back area of ​​the belt are thus connected to one another via the strength members in a force-transmitting connection.

[0020] The two tension cords can be linked by creating the loops of the auxiliary tension cord by means of a laying element and a loop forming element interacting with it in synchronized rotating and lifting movements and placing them around the main tension cord in a crochet-like manner, and by continuously winding the two tension cords linked in this way onto the tool drum in a synchronized rotating movement of the tool drum which is dependent on the crocheting process and the distance between the grooves, the loops being inserted into the grooves.

[0021] It is also possible to place only a specific number of loops with a specific distribution in the tooth tip area. This can be adjusted using a control and drive device that allows for targeted pattern formation, according to which a selection is made as to which, how many, and in what sequence the respective teeth are equipped with the auxiliary tension cord.

[0022] In order to use the described manufacturing process, a special manufacturing device is necessary.The invention therefore relates to a device for producing a toothed belt made of rubber and / or plastic, with a cylindrical tool drum which is rotatable about its longitudinal axis and on which a belt body which is toothed at least on one side and has a radially inner tooth head region, a belt back region which is radially outer with respect to the toothing and a tooth root region arranged radially between them can be produced, wherein the tool drum has grooves aligned in the longitudinal direction on its outer circumferential surface, wherein the grooves have the tooth shape of the toothing of the toothed belt to be produced, with a tension cord laying unit which is movable in the longitudinal direction of the tool drum and by means of which at least one main tension cord can be wound onto the tool drum, which acts as the main strength member and can be arranged in the tooth root region and / or in the belt back region of the belt body.

[0023] To achieve the object relating to the device, the invention provides that an auxiliary tensile cord laying unit is arranged on the tensile cord laying unit, by means of which at least one auxiliary tensile cord can be arranged in the belt body, which auxiliary tensile cord acts as an additional strength member, that by means of the auxiliary tensile cord laying unit the auxiliary tensile cord can be laid around the main tensile cord in such a way that loops can be formed with the auxiliary tensile cord, and that by means of the auxiliary tensile cord laying unit the loops of the auxiliary tensile cord can be inserted into the grooves when the main tensile cord and the auxiliary tensile cord are wound onto the tool drum, that in the finished product the auxiliary tensile cord is arranged substantially in the tooth tip region and is operatively connected to the main tensile cord running in the belt back region or tooth root region.

[0024] A device for producing the timing belt accordingly has an auxiliary tension cord laying unit, which enables the loop formation and connection of the two tension cords and their laying on the tool drum. The auxiliary tension cord laying unit can be attached to an existing device. The main tension cord laying unit and the auxiliary tension cord laying unit can also form a new, integrated laying unit.

[0025] According to a first embodiment of the device, the auxiliary tension cord laying unit can comprise a laying element and a loop-forming element arranged adjacent thereto, wherein the laying element is designed as a cylindrical hollow element with a laying eyelet at its axial end. Accordingly, the auxiliary tension cord laying unit comprises a hollow element, for example a needle-like circular tube or square tube, through which the main tension cord is guided axially. This hollow element is equipped with a laying eyelet at one axial end, through which the auxiliary tension cord is guided. Instead of a laying eyelet, a guide groove or the like can also be provided. The hollow element is capable of performing controlled rotary and lifting movements in a predefined relationship, wherein the control is adapted, for example, to the distance between the longitudinal grooves on the tool drum.

[0026] Furthermore, it is preferably provided that the loop-forming element is designed as a loop-forming wheel with a circumferential arrangement of individually axially displaceable retaining pins, that the axially displaceable retaining pins serve to form the loops of the auxiliary tension member, that the spacing of the retaining pins from one another is adapted to the spacing of the grooves from one another on the outer surface of the tool drum, and that the hollow element and the loop-forming wheel are drivable for a rotary movement. Accordingly, the auxiliary tension member laying unit has a loop-forming wheel in which pin elements are received, by means of which the loops of the auxiliary tension member to be laid in the grooves of the tool drum can be created.

[0027] Furthermore, it can be provided that the drives of the hollow element, the loop forming wheel, and the tool drum are controllable and synchronizable with each other. For this purpose, a common control and drive device is provided, by means of which the drive and / or adjustment of the tool drum, the hollow element, the loop forming wheel, as well as the retaining pins of the loop forming wheel, can be controlled in a synchronized manner based on sensor information and predefined control commands. By using only one drive unit or a few drive units that drive all components to be actuated, as well as a single control unit that allows all components to be adjusted and controlled, a compact and user-friendly design of the production system for manufacturing the timing belt is possible.

[0028] The tool drum, the hollow element, the loop forming wheel, and the retaining pins of the loop forming wheel can be driven and / or adjusted mechanically, pneumatically, and / or electrically using suitable actuators and motors. The installation of precisely controllable drives ensures a precisely synchronized movement sequence of the interacting components. Furthermore, a high laying speed of the tension cords on the tool drum can be achieved.

[0029] According to another embodiment, it is preferably provided in the manufacturing device that the hollow element is aligned perpendicular to the longitudinal axis of the tool drum, that the hollow element is movable parallel to the longitudinal axis of the tool drum, and that the hollow element is rotatable about its longitudinal axis and displaceable in its longitudinal direction.

[0030] According to another development of the invention, it is provided that the loop forming wheel is rotatable about an axis which is arranged parallel to the longitudinal axis of the tool drum, and that the loop forming wheel can be moved together with the hollow element parallel to the longitudinal axis of the tool drum.

[0031] Furthermore, it can be provided that the main tension cord can be guided through the hollow element for winding onto the tool drum, that the auxiliary tension cord can be guided through the laying eyelet for winding onto the tool drum, that the auxiliary tension cord can be laid around the main tension cord by means of the hollow element, that the loops of the auxiliary tension cord can be formed by means of the retaining pins and that the formed loops can be inserted into the grooves on the outer surface of the tool drum by means of the loop forming wheel.

[0032] The size of the loops and their arrangement in the tooth head area can be predefined using the diameter of the retaining pins and the circular diameter of the pin arrangement. The spacing of the pins is therefore adapted to the spacing of the grooves on the tool drum. Other elements, such as belt straps, metal chains, or steel bands with a corresponding retaining pin arrangement, are also possible as loop elements.

[0033] Furthermore, the device can be provided with the main tensile strand and the auxiliary tensile strand wound onto spools and unwound from these spools and fed to the tool drum, and with the spools being used to exert defined tensile forces on the main tensile strand and the auxiliary tensile strand during unwinding from these spools and during winding of the tensile strands onto the tool drum. Accordingly, tensile moments and / or twisting moments can be exerted by means of defined braking of the spools and different angular velocities of the spools and the tool drum or non-rotating spools, so that the tensile strands are wound onto the tool drum with a defined force. This creates a stable and non-slip winding, optionally with a pre-tension, on the tool drum before the vulcanization process of the material structure is carried out after a final application of a rubber layer.

[0034] The invention will be further explained below with reference to some exemplary embodiments in the accompanying drawings. Fig. 1 a schematically simplified representation of a device for producing a toothed belt with a tool drum and a loop forming wheel, Fig. 2 the device according to Fig. 1 in a schematic overview, with a tension cord laying unit with an integrated auxiliary tension cord laying unit, Fig. 3 the loop forming wheel according to Fig. 1 with an arrangement of retaining pins in a radial plan view, Fig. 4 the loop forming wheel according to Fig. 1 in a partial longitudinal section, Fig. 5 the auxiliary tension cord laying unit according to Fig. 2 in detail, Fig. 6 the loop forming wheel according to Fig. 1, Fig. 3 and Fig. 4 in a partial cross-section, Fig. 7 shows a first phase of loop formation in a method for producing a toothed belt according to the invention, Fig. 8 a second phase of loop formation in the process, Fig. 9 a third phase of loop formation in the process, and Fig. 10 is a schematic side view of a portion of a toothed belt manufactured according to the invention.

[0035] How Fig. 10 shows, a toothed belt 4 constructed according to the invention consists of a belt body a, which has a radially inner tooth head region b, a belt back region c which is radially outer with respect to the toothing, and a tooth root region d arranged radially therebetween. The toothed belt a consists essentially of rubber and / or a plastic, with which at least one main tensile strand 5 acting as the main strength member is arranged in the tooth root region d. Further main tensile strands 5, not shown, can additionally be arranged in the belt back region c following the annular circumferential contour of the toothed belt 4. The toothed belt 4 also has at least one auxiliary tensile strand 6 which acts as an additional strength member. The auxiliary tensile strand 6 is arranged essentially in the tooth head region b of the toothed belt 4 and is operatively connected to the main tensile strand 5.This active connection with the main tension cord 5 is created by loops 15 of the auxiliary tension cord 6 wrapping around the main tension cord 5.

[0036] Such a toothed belt 4 designed according to the invention can be produced on a special production device and according to a special production method. Fig. Figure 1 shows essential parts of such a device for producing a toothed belt 4. The device comprises a tool drum 1, which is rotatably mounted about its longitudinal axis 22 and can be driven by a drive motor. The tool drum 1 has grooves 2 on its radially outer surface, which extend parallel to the longitudinal axis 22 of the tool drum 1 and represent the tooth shape of the toothed belt 4. Such a tool drum 1 is known per se as a standard tool for producing rubber toothed belts.

[0037] As mentioned at the beginning, the toothed belt 4 with the features of the invention has two strength members, of which at least one main tension member 5 is arranged in the belt back region c and in the tooth root region d and at least one auxiliary tension member 6 is arranged essentially in the tooth head region b. As Fig. 1, the toothed belt 4 is produced after the main tension cord 5 and the auxiliary tension cord 6 have been wound onto the tool drum 1 and a mat made of rubber has been applied in a conventional vulcanization process which is not described further here.

[0038] The first strength member of the toothed belt 4 is designed as a main tension member 5, as it usually runs in the belt back area of ​​a radially internally toothed toothed belt 4, and which is placed on the tool drum 1 by means of a tension member laying unit 7 with a simple laying roller.

[0039] Instead of the previously used laying roller, an auxiliary tensile strand laying unit 8 is now arranged, with the aid of which an auxiliary tensile strand 6 is placed onto the tool drum 1 as a second strength member in addition to the main tensile strand 5. For this purpose, the auxiliary tensile strand laying unit 8 has a loop forming wheel 9, which is arranged adjacent to the tool drum 1 and can be rotated in the opposite direction to the tool drum 1.

[0040] This loop forming wheel 9 serves, on the one hand, to apply the auxiliary tension cord 6 to the tool drum 1 in accordance with the pitch. On the other hand, it ensures a desired arrangement of loops 15 of the auxiliary tension cord 6 in the grooves 2 of the tool drum 1. Fig. In this context, Figure 1 shows that loops 15 are first formed with the aid of retaining pins 14 using the auxiliary tension cord 6 on the loop-forming wheel 9 and then inserted into the grooves 2 of the tool drum 1. The auxiliary tension cord 6 is wound around the main tension cord 5. During synchronous rotation of the tool drum 1 and the loop-forming wheel 9, the pins 14 are successively pulled out of the loops 15 already inserted into the grooves 2.

[0041] Fig. Figure 2 shows an overview of the device for producing a toothed belt 4 according to the invention. In this device, the main tension cord 5 is unwound from a first spool 10 and fed to the auxiliary tension cord laying unit 8. At the same time, the auxiliary tension cord 6 is unwound from a second spool 11. This second spool 11 is part of the auxiliary tension cord laying unit 8 and can be braked in a defined manner in order to exert a tensile force on the auxiliary tension cord 6 during its laying. In the auxiliary tension cord laying unit 8, the auxiliary tension cord 6 is wrapped around the main tension cord 5, and loops 15 are formed at successive sections of the auxiliary tension cord 6, as described in more detail below.

[0042] The tensile cords 5, 6 linked together in this way are wound onto the tool drum 1. For this purpose, the tool drum 1 is driven to rotate by a control and drive device 16. Simultaneously, the control and drive device 16 drives the main tensile cord laying unit 7 and the auxiliary tensile cord laying unit 8. This drive is achieved here, for example, by means of a belt drive 21, which drives a spindle 17 with an external thread. The external thread of the spindle 17 interacts with associated internal threads on the main tensile cord laying unit 7 and the auxiliary tensile cord laying unit 8 such that they are axially displaceable. The integrated laying unit 7, 8 formed from the main tensile cord laying unit 7 and the auxiliary tensile cord laying unit 8 can thus be moved past the outer surface of the tool drum 1 at a defined speed.The two tension cords 5, 6 are wound onto the tool drum 1 with a defined force, for example in the range between 50 N and 200 N, and at a defined thread spacing to form a helix, and the loops 15 of the auxiliary tension cord 6 are inserted section by section into the longitudinal grooves 2 of the tool drum 1. In this way, a tension cord layer is formed on the tool drum 1, in which the main tension rod 5 is arranged in the belt back c and / or in the tooth root area d and the loops 15 of the auxiliary tension cord 6 are arranged in the tooth tip area b. A comparatively short section of the auxiliary tension cord 6 is arranged between the grooves 2 in the tooth tip area b and / or in the belt back area c.

[0043] Further details of the manufacturing device are shown in the Fig. 3 to 6. Accordingly, the loop forming wheel 9 according to the radial plan view in Fig. 3 has a plurality of retaining pins 14 evenly distributed over its circumference, which are arranged in bores of the loop forming wheel 9 so as to be axially displaceable by means of an actuator (not shown). Fig. Figure 4 shows a section of the loop forming wheel 9 with the retaining pins 14 in a front view. The pitch of the teeth or the pin arrangement is adapted to the pitch of the teeth or the grooves 2 of the tool drum 1. Conventional pitches, for example, 8 mm or 9.525 mm, can be used, with the pitch of the teeth resulting from the ratio of the respective pitch circle diameter of the respective toothing to the number of teeth multiplied by the number π.

[0044] The structure of the auxiliary tension cord laying unit 8 is best described in a summary of the Fig. 2 and Fig. 5. Accordingly, the auxiliary tension cord laying unit 8 comprises a needle-shaped hollow element 12 in addition to the loop forming wheel 9. At its upper end, the hollow element 12 has a laying eyelet 13. The hollow element 12 is rotatable about its longitudinal axis and displaceable in both directions along its longitudinal axis. This is indicated by two arrows on the hollow element 12.

[0045] The loop forming wheel 9 is rotatably mounted on a drive mount 3, by means of which the main tension cord laying unit 7, together with the auxiliary tension cord laying unit 8, can be moved parallel to the longitudinal axis 22 of the tool drum 1 on the aforementioned spindle 17 (direction of movement 18). The spindle 17 is rotatably mounted in at least two bearings 19, 20 in the region of its axial ends. The spindle 17 can also be driven by a separate motor. The retaining pins 14 can be individually moved axially in the loop forming wheel 9 by means of an actuating device (not shown).

[0046] The main tension cord 5 is guided coaxially through the needle-shaped hollow element 12 of the auxiliary tension cord laying unit 8. At the same time, the auxiliary tension cord 6 is unwound from the second spool 11 and guided through the laying eyelet 13 of the hollow element 12. The laying eyelet 13 guides the auxiliary tension cord 6 during the formation of the loops 15 through 360° rotations with simultaneous lifting movements in a synchronized sequence with the rotations of the tool drum 1 and the loop forming wheel 9 as well as the axial movement of the holding pins 14. Similar to a crocheting process, by means of this rotating and lifting movement, one loop 15 of the auxiliary tension cord 6 is placed after the other loop 15 around the respective engaging holding pin 14 and around the main tension cord 5. Fig. 6 shows an axial section through the loop forming wheel 9. It shows a currently active retaining pin 14, the main tension cord 5 and the position of the auxiliary tension cord 6.

[0047] The Fig. Figures 7 to 9 show different phases of loop formation. Fig. 7, the retaining pin 14 is already axially pushed into its loop-forming position, and the thread laying eyelet 13 is positioned in a raised, upper position. Fig. 8, the laying eyelet 13 is rotated by 180° and the hollow element 12 is in an axially lowered lower position. Fig. 9, the laying eyelet 13 is rotated by a further 180° and is again close to the starting position. The started loop 15 is guided around the main tension cord 5. This process takes place with continuous rotation of the loop forming wheel 9 and the tool drum 1. The position of the auxiliary tension cord laying unit 8 according to Fig. 9 forms, after completion of the loop formation, the starting point for the next loop 15 of the auxiliary tension member 6. Due to the synchronous rotation of the loop forming wheel 9 and the tool drum 1, the loops 15 are deposited in the tooth grooves 2 of the tool drum 1 with the correct pitch.

[0048] It should also be noted here that in the method according to the invention for producing a toothed belt 4, a reinforcing fabric can first be placed on the tool drum 1. The main tension cord 5 is guided through the hollow element 12. With the laying eyelet 13, a loop 15 is formed by one rotation per drum groove 2 or according to a required frequency of loops. To create the loop 15, a retaining pin 14 is first pushed into the area of ​​the loop 15 to be produced ( Fig. 7). The hollow element 12 is then rotated with the laying eyelet 13 while simultaneously lowering the hollow element 12 ( Fig.8). As a result, the auxiliary tension cord 6 is placed over the pin element 14 and the main tension cord 5 and then guided around the main tension cord 5, whereby the diameter of the retaining pin 14 determines the size of the loop. By further rotating the loop forming wheel 9 and the tool drum 1, the auxiliary tension cord 6 with the formed loops 15 is inserted into the axial grooves 2 of the tool drum 1. As soon as a loop 15 is placed on the tool drum 1 and arranged in the associated groove 2, the corresponding retaining pin 14 in the loop forming wheel 9 is retracted axially again, whereby the loop forming wheel 9 continues to rotate in order to lay the next loop 15.After the two tension cords 5, 6 have been completely laid on the tool drum 1, a rubber layer can be applied to the tension cords 5, 6 and the tool drum 1, and then its material can be pressed through the tension cords 5, 6 to the surface of the tool drum 1 and its grooves 2 in a vulcanization step under heat and pressure. This connects the belt body a to the main tension cord 5 in the belt back c and the toothing reinforced by the auxiliary tension cord 6, thus completing the timing belt 4. List of reference symbols 1 tool drum 2 tool groove 3 Drive bracket 4 timing belts 5 Main tension member 6 Auxiliary tension member 7 Tension cord laying unit 8 Auxiliary tension cord laying unit 9 Loop forming element, loop forming wheel 10 Main tension cord coil 11 Auxiliary tension cord coil 12 laying element, hollow element 13 Laying eyelet 14 Retaining pin 15 loops 16 Control and drive device 17 spindle 18 Direction of movement 19 First bearing for the spindle 20 Second bearing for the spindle 21 Drive means, belt drive 22 Longitudinal axis of the tool drum a belt body b Tooth head area c Belt back area d tooth root area

Claims

[1] Device for producing a toothed belt (4) made of rubber and / or plastic, with a cylindrical tool drum (1) rotatable about its longitudinal axis (22), on which a belt body (a) toothed at least on one side with a radially inner tooth head region (b), a belt back region (c) radially outer with respect to the toothing and a tooth root region (d) arranged radially therebetween can be produced, wherein the tool drum (1) has grooves (2) aligned in the longitudinal direction on its outer peripheral surface, wherein the grooves (2) have the tooth shape of the toothing of the toothed belt (a) to be produced, with a tension cord laying unit (7) movable in the longitudinal direction of the tool drum (1), by means of which at least one main tensile strand (5) can be wound onto the tool drum (1), which acts as the main strength member and can be arranged in the tooth root area (b) and / or in the belt back area (c) of the belt body (a), characterized by , that an auxiliary tension cord laying unit (8) is arranged on the tension cord laying unit (7), by means of which at least one auxiliary tensile strand (6) can be arranged in the belt body (a), which acts as an additional strength carrier, that by means of the auxiliary tension cord laying unit (8) the auxiliary tension cord (6) can be laid around the main tension cord (5) in such a way that loops (15) can be formed with the auxiliary tension cord (6), and that by means of the auxiliary tension cord laying unit (8) the loops (15) of the auxiliary tension cord (6) can be inserted into the grooves (2) when the main tension cord (5) and the auxiliary tension cord (6) are wound onto the tool drum (1) in such a way that in the finished product the auxiliary tension cord (6) is arranged essentially in the tooth head area and is operatively connected to the main tension cord running in the belt back area or tooth root area. [2] Device according to claim 1, characterized by , that the auxiliary tension cord laying unit (8) has a laying element (12) and a loop forming element (9) arranged adjacent thereto, that the laying element (12) is designed as a cylindrical hollow element with an axially end-side laying eyelet (13), that the loop forming element is designed as a loop forming wheel (9) with a circumferential arrangement of individually axially displaceable holding pins (14), that the axially displaceable retaining pins (14) serve to shape the loops (15) of the auxiliary tension member (6), that the distance between the retaining pins (14) is adapted to the distance between the grooves (2) on the outer surface of the tool drum (1), and that the hollow element (12) and the loop forming wheel (9) can be driven to rotate. [3] Device according to claim 1 or 2, characterized by that the drives of the hollow element (12), the loop forming wheel (9) and the tool drum (1) are controllable and synchronizable with one another. [4] Device according to one of claims 1 to 3, characterized by that the hollow element (12) is aligned perpendicular to the longitudinal axis (22) of the tool drum (1), that the hollow element (12) can be moved parallel to the longitudinal axis (22) of the tool drum (1), and that the hollow element (12) is rotatable about its longitudinal axis and displaceable in its longitudinal direction. [5] Device according to one of claims 1 to 4, characterized by that the loop forming wheel (9) is rotatable about an axis which is arranged parallel to the longitudinal axis (22) of the tool drum (1), and that the loop forming wheel (9) can be moved together with the hollow element (12) parallel to the longitudinal axis (22) of the tool drum (1). [6] Device according to one of claims 1 to 5, characterized by that the main tension cord (5) can be guided through the hollow element (12) for winding onto the tool drum (1), that the auxiliary tension cord (6) can be guided through the laying eyelet (13) for winding onto the tool drum (1), that the auxiliary tension cord (6) can be laid around the main tension cord (5) by means of the hollow element (12), that the loops (15) of the auxiliary tensile strand (6) can be formed by means of the holding pins (14) and the formed loops (15) can be inserted into the grooves (2) on the outer surface of the tool drum (1) by means of the loop forming wheel (9). [7] Device according to one of claims 1 to 6, characterized by that the size of the loops (15) and the arrangement of the loops (15) in the tooth head area (b) are predetermined by means of the diameter of the retaining pins (14) and by means of the circular diameter of the pin arrangement. [8] Device according to one of claims 1 to 7, characterized by that the main tensile strand (5) and the auxiliary tensile strand (6) are wound onto spools (10, 11) and can be fed from these spools (10, 11) to the tool drum (1), and that a defined tensile force can be exerted on the tensile strands (5, 6) by means of the spools (10, 11) when unwinding them and when winding the tensile strands (5, 6) onto the tool drum (1). [9] Device according to one of claims 1 to 8, characterized by that the tool drum (1), the hollow element (12) and the loop forming wheel (9) as well as the holding pins (14) of the loop forming wheel (9) can be driven and / or adjusted mechanically, pneumatically and / or electrically. [10] Device according to claim 9, characterized by that a common control and drive device (16) is provided, by means of which the drive and / or the adjustment of the tool drum (1), the hollow element (12) and the loop forming wheel (9) as well as the holding pins (14) of the loop forming wheel (9) can be controlled in a synchronized manner.

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