APPARATUS FOR FORMING RING-SHAPED MEMBER

Abstract: An apparatus for forming a ring-shaped member comprising a main body of rotating drum having a rotary shaft; a drum driving device for rotating the main body of rotating drum about the rotary shaft; a plurality of movable members parallely provided in the circumferential direction of the main body of rotating drum and radially movably held by the main body of rotating drum; drum segments fixed to respective movable members and collectively forming the outer peripheral portion of the rotating drum; a stepless expanding-contracting device for simultaneously moving the movable members and the drum segments in the radial direction of the rotating drum to expand or contract the diameter of the rotating drum; and a switching device for switching this stepless expanding-contracting device between a movable state and a stationary state.

Description: BACKGROUND ART The present invention relates to a tyre tread band assembly forming apparatus in which a tread is adhered onto a breaker to form a tyre tread assembly. In production of a radial tyre or other tyre, in general, there has been employed a green tyre production method in which a tyre tread band assembly is at first produced on a special drum by adhering a tread to a breaker, and this then is connected to a toroidal carcass which is formed on another drum. A tyre tread band assembly forming apparatus used in the above method comprises a rotary drum as shown in Fig.5 or 6. In the tread assembly forming apparatus 60 shown in Fig. 5, a rotary drum having a drum shaft 61 is made of a plurality of drum segments 63 each of which is in the form of an arc in a side view thereof. In addition, the tread assembly forming apparatus 60 is provided with an air bag 64 as an expansion and contraction means L for moving the drum segments 63 in radial directions. The air bag is placed over the outer periphery of a support 66 attached to the drum shaft 61. To contact the drum the air bag 64 is contracted and the drum segments 63 are then positioned as shown in the upper half of Fig.5. When the air bag 64 is expanded, the drum segments 63 are pushed radially outwards so that the outer diameter of the rotary drum 62 is expanded as shown in the lower half of Fig.5. Then, a breaker and a tread are applied over the outer periphery of the drum 62. Each drum segment 63 is integrally provided with engagement portions 67 cross section of which is hook-shaped so as to restrict the amount of diameter expansion. The engagement portions 67 engage projections 69 of a restriction rings 68 to set the amount of expansion in diameter. The forming apparatus 70 shown in Fig.6 is provided with air cylinders 71 as expansion and contraction means in place of the air bag 64. The number of air cylinders 72 is the same as that of the drum segments 72. In this case, the expanded length of the air cylinder 71 is considered as the amount of expansion of the drum diameter. Furthermore, the apparatus 70 is provided with a restriction block 74 so as to keep a predetermined expansion distance. The expansion length x set by the restriction block 74 is the amount of expansion of the drum diameter. In Fig 5 and 6, the breaker and tread are indicated by 75. Fig.7 is a diagram showing the positions of the drum segments 63 (72) when viewed in the direction of arrow A in Fig 5 and 6. It shows the positions of the drum segments 63 (72) contracted and expanded in the upper and lower half portions of Fig.7 respectively. As seen in Fig.7 in the conventional apparatus a peripheral surface is, when contracted formed by the respective longitudinal end edges of the drum segments 63 (72) being kept in contact with one another. On the other hand when expanded spaces exist between adjacent drum segments 63 (72). Thus in the conventional apparatus, it is necessary to use a restriction ring 68 or restriction blocks 74 to keep set and keep the predetermined expansion diameter amount x. Moreover, it is necessary to provide variously sized restriction rings 68 or restriction blocks 74 for different sizes of tyre. Also every time the diameter of a tyre is changed, the restriction ring 68 or restriction block 74 must be changed. Consequently, management of parts and the preparatory working for tyre building are complicated. Furthermore, the air bag 74 or air cylinder 71 has a limited effective stroke. If a tyre having a greater size than the limited effective stroke allows is to be built, it is necessary to use a rotary drum provided with expansion and contraction means having a greater effective stroke. In the conventional apparatus, spaces 'a' exist Between the drum segments when expanded. Accordingly, a band like material such as a breaker is likely to take a polygonal form when assembled over the rotary drum, which consequently provides undesirable quality. A tyre tread band assembly apparatus according to the preamble of claim 1 is known, for example, from FR-A-2216100. DISCLOSURE OF THE INVENTION To solve the above drawbacks, the following construction is employed in the present invention. A tyre tread band assembly forming apparatus comprising a rotary drum having a rotary shaft drum driving means for rotating the rotary drum about the rotary shaft, a plurality of movable members arranged around the peripheral direction of the rotary drum and radially movable drum segments fixedly attached to respective movable members for forming the outer periphery of the rotary drum continuous expansion and contraction means for simultaneously moving the movable members and drum segments in radial directions of the rotary drum so as to expand and contract the diameter of the rotary drum, and changer means for changing the continuous expansion and contraction means from the operation or building state to a suspension state for band removal and vice versa, characterised in that the movable member is a threaded rod, the continuous expansion and contraction means includes a threaded nut or cylinder having a through hole engageable with the threaded rod in the centre thereof, small bevel gears fixed onto the periphery of the threaded nut of cylinder and rotatable relative to the rotary drum body and a large gear coaxially and rotatably mounted on the drum shaft and engaged with each small bevel gear and the changer means is provided between the bevel gears and the drum shaft and includes a clutch for allowing rotation of the bevel gears and drum shaft independently of each other or together with each other. With the above construction, the continuous expansion and contraction means is first changed to the operational state, all the movable members and drum segments being moved in their respective radial directions simultaneously. When the drum segments reach the required position, the continuous expansion and contraction means is stopped at suspended state and the diameter of the rotary drum is thus held and set at the required building diameter at which the rotary drum can be rotated to allow assembly of the tread band assembly. The building diameter of the rotary drum can be continuously adjusted and set at any required diameter without needing different restriction blocks or restriction rings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view of a tyre tread band assembly forming apparatus of one embodiment of the present invention: Fig.2. is a sectional view of a clutch for the apparatus: Fig.3. is a diagram showing an arrangement of drum segments when viewed in the direction of arrow Z in Fig.1: Figs.4 (a) and (b) are diagrams illustrated the positional relationships between drum segments at the time of contraction and expansion of the rotary drum: Figs.5 and 6 are section views of conventional tyre tread assembly forming apparatus. Fig.7 is a diagram showing the arrangements of the drum segments when viewed in the direction of arrow A in Figs 5 and 6 and Fig. 8 is a block diagram showing the control means for adjusting automatically the diameter. BEST MODE OF CARRYING OUT THE INVENTION Now there will be described one embodiment of the present invention with reference to Figs 1 to 4. A tyre tread assembly forming apparatus 1 comprises a rotary drum 5. The rotary drum 5 includes a drum shaft (rotary shaft) 2 and a housing (a rotary drum body) 7. The drum shaft 2 is supported on a frame 4 by means of a hollow shaft 17 to be described below and bearings 3 and 18. The housing 7 is rotatable together with the drum shaft 2. A plurality of small bevel gears 10 (eight small bevel gears in this embodiment) are provided in an outer peripheral portion of the housing 7 running in bearings 8. A threaded nut 11 is fixedly attached inside each small bevel gear 10. The threaded nut is engaged with a threaded rod (moving member) 12. Various screw threads having forms including than a trapezoidal screw or ball screw can be used for the screw of the nut 11 and threaded screw rod 12. The threaded rod 12 has a drum segment 15 provided at one end portion thereof. As shown in Figs 4 (a) and (b), the drum segment 15 has end portions 15a and 15b which are formed in a comb-like shape. The end portion 15a (15b) of one drum segment 15 is engaged with the end portion 15b (15a) of another drum segment 15 adjacent to the first drum segment 15 i the peripheral direction so as to form the outer periphery of the rotary drum 5. The hollow shaft 17 is rotatably mounted around the drum shaft 2 by bearings 3 coaxial with the drum shaft 2. Also, the hollow shaft 17 is rotatably supported in the frame 4 by bearings 18 independently of the drum shaft 2. The hollow shaft 17 has a single large bevel gear 20 formed on an end thereof. The large bevel gear 20 is engaged with all the small bevel gears 10. The hollow shaft 17, large bevel gear 20, small bevel gears 10 and threaded nuts 11 constitute continuous expansion and contraction means N for moving the threaded rods 12 and the drum segments 15 simultaneously. A clutch (changer means) 22 is provided between the drum shaft 2 and hollow shaft 17. When the clutch 22 is released, the shafts 2 and 17 may be rotated independently of each other. When the clutch 22 is engaged, the shafts 2 and 17 rotate together. As shown in Fig.2 the clutch 22 has an idle member 21a. The idle member 21a can be moved in the same direction as that of the drum shaft 2 relative to a body fixedly attached to the drum shaft 2. A connector 21b is fixedly attached to the hollow shaft 17. The connector 21b is engaged with the idle member 21a by means of engaging teeth. The idle member 21a and the body are formed with engaging teeth 24 respectively, the engaging teeth 24 can be engaged with each other. The idle member 21a is usually held by the force of a compression spring 21c in a state in which the engaging teeth 24 are separated from each other the state shown in an upper half portion of Fig 2). When air is supplied to the clutch through an air hole, 16, the air pressure causes the idle member 21a to move against the force of the spring 21c. In addition, the engaging teeth 24 are engaged with each other ( in the state shown in a lower half portion of Fig 2) to transmit the torque. Now there will be described a drive mechanism for the rotary drum 5 with reference to Fig 1. The frame 4 has upper and lower intermediate shafts 39 and 40 rotatably provided inside thereof. The intermediate shafts 30 and 40 are parallel with the hollow shaft 17. The upper intermediate shaft 30 has a sprocket 31 directly attached thereto and a sprocket attachable thereto by a clutch 37. When the clutch 37 is locked, the sprocket 33 rotates together with the intermediate shaft 30. When the clutch 37 is released, the sprocket 33 ring rotates independently of the intermediate shaft 30. Also sprockets 25, 26 and 27 are provided on the outer periphery of the hollow shaft 17 which is in the frame 4. The sprocket 25 drives the sprocket 31 of the intermediate shaft 30 by a chain 29. The sprocket 33 of the intermediate shaft 30 is driven by an output shaft of a motor (drum driving means) 35 by chain 34. The motor 35 is mounted on the frame 4. When the clutch 37 is locked, the torque of the motor 35 is transmitted to the hollow shaft 17 by the chain 34, clutch 37, sprocket 33, intermediate shaft 30, sprocket 31, chain 29 and sprocket 25 (which constitutes a drive transmission mechanism), so that the hollow shaft 17 is rotated. When the clutch is released, the hollow shaft 17 may rotate independently of the motor 35. The sprocket 27 is associated with a rotary member of a pulse generator 51 by a chain 50. The pulse generator 51 is fixedly attached to an inner side wall of the frame 4 and sends a pulse signal to a calculation unit 56 (which constitutes a display means). The pulse signal sent from the pulse generator 51 corresponds to the rotational amount of the sprocket 27 (i.e. the amount of rotational of the hollow shaft 17) which is transmitted by the chain 50. The calculation unit 56 counts the number of pulses of the pulse signal. Subsequently, the radial displacement of the drum segment 15, i.e. the outer diameter of the rotary drum 5 is calculated from the count of pulses. The outer diameter thus calculated is displayed in a display unit 57 (which constitutes a display means). Next, there will be described the expansion and contraction adjustment means M. The expansion and contraction adjustment means M is adapted for contracting the rotary drum 5 to allow removal of the assembly tyre band and expansion of the assembly, and expanding the rotary drum 5 to give additional tension in the assembly. The intermediate shaft 40 has a pinion gear 45 fixedly attached thereto and a sprocket 41 attached thereto and a sprocket 41 attached thereto by a clutch 43. When the clutch 43 is locked, the torque of the sprocket 41 is transmitted to the intermediate shaft 40. When the clutch is released, the torque of the sprocket 41 is not transmitted to the intermediate shaft 40. The sprocket 41 is associated with the sprocket 26 on the hollow shaft side 17 by a chain 42. On the other hand, two air cylinders 47 and 49 are arranged in series in a lower portion of the frame 4 facing in opposite directions. The lower air cylinder 49 has a piston rod connected to the frame 4. The upper air cylinder 47 has a piston rod fixed to a rack gear 48. The rack gear 48 is engaged with the pinion gear 45. A clutch 55 is provided between the drum shaft 2 and the frame 4. When the clutch 55 is locked, the drum shaft 2 is fixedly connected to the frame 4. When the clutch 44 is released, the drum shaft 2 can be rotated. Next, there will be described the steps of building a tyre tread component including a breaker band by use of the above-mentioned apparatus. The building steps are divided broadly into a process of adjusting and setting the diameter of the rotary drum and a process of applying materials over the rotary drum. Firstly, the clutch 55 is locked to fix the drum shaft 2 to the frame 4. On the other hand, the clutches 22, 37 and 43 are released so that the hollow shaft 17 can be rotated independently of the drum shaft 2, motor 35 and intermediate shaft 40. The piston of one of the cylinders 47 and 49 is projected and that of the other cylinder is contracted. Then, a hand wheel 23 is manually rotated to rotate the hollow shaft 17. This torque is converted into a driving force for the axial movement of the screw rod 12 by way of the large bevel gear 20, small bevel 10 and screw cylinders 11. Consequently, all the drum segments 15 are moved in radial directions (moved inward or outward), so that the diameter of the rotary drum 5 is changed. During this operation, the change of the diameter of the rotary drum is calculated by the calculation unit 56 which received a detecting signal from the pulse generator 51, and then displayed in the display unit 57. The calculation are executed as follows. In initial state, if the reference diameter is DO, lead of the screw (an advancing amount of the screw per revolution) is ℓ the gear ratio of the large bevel gear 20 to the small bevel gear 10 is R1, the number of revolutions of the hollow shaft 17 is m and the sprocket ratio of the pulse generator 51 to the hollow shaft 17 is 1, the actual drum diameter ( segment diameter) D1 is expressed by the following equation: D1 = DO + 2 (ℓ x R1 x m) If the pulse generator generates n pulses per revolution and the actually counted pulse number is N, the following equation can be expressed: N = m x n Equations (1) and (2) are combined at the common variable m to produce an equation which makes it possible to calculate the actual segment diameter D1 based on the pulse number N. The segment diameter D1 and pulse number N calculated by the calculation unit 56 are displayed in the display unit 57. The operator carries out the adjusting operation watching the displayed segment diameter. When the segment diameter reached the desired diameter, i.e. the application diameter, the rotation of the hand wheel 23 is stopped. In this state, the clutch 22 is locked and the hollow shaft 17 is fixed to the drum shaft 2. Consequently, the drum segments 15 cannot be moved relative to the housing 7 of the rotary drum 5, so that the desired application diameter is held. Process of applying materials over the rotary drum as mentioned above is that after the application diameter is set, the clutch 55 is released to allow the drum shaft 2 and hollow shaft 17 to rotate relative to the frame 4. The clutch 37 is locked to allow the drum shaft 2 to rotate together with the hollow shaft 17 by the torque of the motor 35. In this state, when the motor 35 is driven, the drum segments 15 are rotated together with the housing 7 but the drum shaft 2 cannot be rotated relative to the hollow shaft 17. Consequently relative movement does not occur between the large bevel gear 20 and small bevel gears 10 and the drum diameter is therefore neither expanded nor contracted. In this state, also, the pulse generator 51 is electrically disconnected from the calculator unit 56 so that the pulse number is not counted. The application diameter set by the above process is stored. The breaker and tread are applied over the drum segments 15 to form a tyre tread assembly while the rotary drum 5 is rotated by the torque of the motor 35. Although the diameter of the rotary drum 5 is expanded the respective end portions 15a and 15b of the drum segments 15 are in the engagement positions as shown in Fig. 4 (b). Unlike the conventional construction shown in Fig.7. there are no spaced a. Accordingly, there is no likelihood that the outer periphery of the rotary drum 5 has a polygonal form. Consequently, the band member can be smoothly formed and its quality can be improved. When removing the assembly (a) the clutch 55 is locked to fix the drum shaft 2 relative to the frame 4, (b) the clutches 22 and 37 are released to allow the hollow shaft 17 to rotate independently of the drum shaft 2, and (c) the clutch 43 is locked. In this state, the projected piston rod of the air cylinder 47 or 49 of the expansion and contraction adjustment means M is contracted. The vertical movement of the rack gear 48, which is caused by the contraction of the piston rod, is transmitted to the hollow shaft 17 by way of the piston gear 45, intermediate shaft 40, clutch 43, sprocket 41, chain 42 and the sprocket 26 (which constitute the drive transmission mechanism). The revolution of the hollow shaft 17 is transmitted to the drum segments 15 by way of the large bevel gear 20, small bevel gears 10, screw cylinders 11 and screw rods 12, and the drum segments 15 are moved inward. Consequently, the outer diameter of the rotary drum 5 is contracted to a diameter enabling the band member to be removed. It is sufficient to contract the rotary drum 5 to a diameter which merely allows the removal of the assembly (breaker-tread band) to be removed from the rotary drum 5, preferably, 10 to 20 mm. The amount of contraction can be arbitrarily set by the cylinder stroke of the cylinders 47 and 49 the gear ratio of the rack gear 48 to the pinion gear 45 and/or the ratio of the sprocket 41 to the sprocket 26. One example of the calculation is as follows:- (the amount of expansion and contraction) = (s / r0) x R1 x R2 x ℓ s : cylinder stroke R0 : pitch circumference of the pinion gear R1 : bevel gear ratio R2 : sprocket ratio ℓ : lead of the screw rod After forming the tread assembly, there may be the necessity of expanding the diameter of the band member to give additional tension in order to discharge the air left in the breaker or to eliminate partial sag which is caused by unevenness of applied tension. In this case, the expansion and contraction adjustment means M is useful. Specifically, under the same condition as the removal operation, the piston rod of the contracted at cylinder 47 (49) is projected to move the drum segment 15 further outward and increase the outer diameter of the rotary drum 5. Consequently, a proper tension can be given to the band member positioned on the outside surface thereof. When removing the band member after the further expansion, the reverse operations are performed to decrease the diameter of the rotary drum 5. It should be noted that the present invention is not limited to the above-mentioned embodiments, for example, there may the following ways. (1) In the above embodiment, a worker manually operates the hand wheel 23 seeing the display unit 57 to adjust the application diameter. However, adjustment of the application diameter may be automatically performed by use of an appropriate device. Fig.8 is a block diagram showing a construction which enables automatic adjustment of the application diameter. In the drawing, a controller 59 receives the pulse signal from the pulse generator 51. Also, in the controller 59 is set in advance a pulse NO corresponding to the desired application diameter. In the adjustment of the drum diameter, first, the controller (control means) 59 locks the clutch 37 and at the same time allows the motor 35 to rotate and then the hollow shaft 17 to rotate to change the diameter of the rotary drum 5. Also, the controller 59 counts the number 'N of pulses of the pulse signal from the pulse generator 51. When the pulse number 'N becomes equal to the preset pulse number NO. the controller 59 releases the clutch 37 to stop the motor 35. With this construction, the diameter of the rotary drum 5 can automatically be adjusted by the controller 59. In addition, the motor 35, which is adapted for driving the rotary drum 5, is used as drive means for the adjustment of the drum diameter. Accordingly, the adjustment can be executed with a simple and small construction and at a low cost. In place of such combined use, however, it may be appropriate to provide another drive means for the adjustment of the drum diameter, i.e. separate drive means for the continuous expansion and contraction means N. In the construction of Fig.1, there may be provided a motor similar to the motor 35 a drive shaft of which is connected to the hollow shaft 17 by a clutch. (2) In this apparatus, without using the expansion and contraction adjustment means M, only by use of the continuous expansion and contraction means N, the rotary drum can be contracted to a diameter at which the formed band member can be removed, and expanded to the diameter at which additional tension is given to the formed band member. Specifically, a pulse number corresponding to a fine adjustment of the drum diameter is calculated in advance. The hollow shaft 17 is rotated relative to the drum shaft 2 by driving the motor 35 in accordance with the calculated pulse number. However, it will be seen that the use of the above-mentioned expansion and contraction adjustment means M makes fine adjustment easier. (3) In the above mentioned embodiments, the hollow shaft 17 is coaxially arranged around the drum shaft 2, and is formed with the large bevel gear 20 on the end portion thereof. However, the present invention does not limit to such a construction. It may be appropriate to employ a construction in which a separate large bevel gear 20 may be rotatably provided on the drum shaft 2 by a clutch, and be rotated independently of the drum shaft 2 by releasing the clutch, and be rotated together with the drum shaft 2 by locking the clutch. (4) According to the present invention, the changer means are not limited to the above specific construction, and may be constituted by various clutches other than the air clutch or means other than clutches. For example, the hollow shaft 17 may be attached to the drum shaft 2 by use of a bolt. When the drum diameter is adjusted, i.e. the continuous expansion and contraction means N is operated, the bolt is loosened to allow the hollow shaft 17 to rotate independently of the drum shaft 2. After the adjustment, the bolt is tightened to allow both drum shaft 2 and hollow shaft 17 to rotate together with each other. (5) In the above embodiments, the drum diameter is displayed by the display unit 58. If the operator knows the relationship between the drum diameter and the pulse number, the pulse number may be directly displayed. (6) The present invention is not limited to such forming of a tyre tread assembly as mentioned above, but is broadly applicable to forming other similar band members. INDUSTRIAL EXPLOITABILITY As described above, the present invention is useful as an apparatus for forming tyre tread assembly, in particular, as an apparatus for forming a breaker band by assembly together a breaker and a tread for tyre. The diameter of the rotary drum can be adjusted without steps or continuously. The adjusted diameter can be held. Accordingly, various kinds of band member having different diameters can be formed easily without using conventional restriction blocks or restrictions members.

Claims: A tyre tread band assembly forming apparatus comprising a rotary drum (5) having a rotary shaft (2) drum driving means for rotating the rotary drum (5) about the rotary shaft (2), a plurality of movable members (12) arranged around the peripheral direction of the rotary drum (5) and radially movable drum segments (15) fixedly attached to respective movable members (12) for forming the outer periphery of the rotary drum (5) continuous expansion and contraction means (N) for simultaneously moving the movable members (12) and drum segments (15) in radial directions of the rotary drum so as to expand and contract the diameter of the rotary drum (5), and changer means (22) for changing the continuous expansion and contraction means from the operation or building state to a suspension state for band removal and vice versa, characterised in that the movable member (12) is a threaded rod, the continuous expansion and contraction means includes a threaded nut or cylinder (11) having a through hole engageable with the threaded rod (12) in the centre thereof, small bevel gears (10) fixed onto the periphery of the threaded nut of cylinder (11) and rotatable relative to the rotary drum body (5) and a large gear (20) coaxially and rotatably mounted on the drum shaft (3) and engaged with each small bevel gear (10) and the changer means (22) is provided between the bevel gears and the drum shaft (2) and includes a clutch for allowing rotation of the bevel gears and drum shaft independently of each other or together with each other. An apparatus according to claim 1, characterised by a hollow shaft (3) rotatably mounted around the periphery of the rotary shaft (2) coaxially with and independently of the rotary shaft (2) when a clutch (22) is provided between the hollow shaft (3) and the drum shaft (2) and the large bevel gears (20) mounted on the hollow shaft (3). An apparatus according to claim 1 or 2, characterised by driving means (38) for driving the continuous expansion and contraction means. An apparatus according to claim 1, 2 or 3, characterised by a transmission mechanism for transmitting the driving force of the drum driving means (38) to the continuous expansion and contraction means. An apparatus according to claim 1, 2, 3 or 4, characterised by means for adjusting the diameter of the continuous expansion and contraction means by allowing the drum segments (18) to move by a predetermined amount (x). An apparatus according to claim 5, characterised in the adjusting means includes a cylinder (17) having an expandable piston rod, and a mechanism for covering the expansion of the piston rod to rotation of the hollow shaft (3). An apparatus according to any of claims 1 to 6, characterised by the drum segments (18) each have comb-like shaped end portions (15a, 15b) engageable with end portions of adjacent segment combs even when the rotary drum is expanded. An apparatus according to any of claims 1 to 7, characterised by means for detecting the amount of movement of the drum segments (15) and means for displaying the outer diameter of the rotary drum (5) based on the amount detected of movement. An apparatus according to claim 3 or 4, characterised by means for detecting the amount of movement or the drum segment, and means for controlling the driving of the continuous expansion and contraction means based on comparison of the detected amount of movement with a predetermined desired building or material application diameter.

Inventors: OSA MASAYUKI, OSA, MASAYUKI, OSA, MASAYUKI 671-231, AZA OOTANI SHIOYACHO
Applicants: SUMITOMO RUBBER IND, SUMITOMO RUBBER INDUSTRIES LTD.
Application year: 1990
Main classification: B29D30
IPC codes: B29D30