GB1563342A

GB1563342A - Tyre construction drums

Info

Publication number: GB1563342A
Application number: GB4553176A
Authority: GB
Original assignee: Metzeler Kautschuk AG
Current assignee: Metzeler Kautschuk AG
Priority date: 1975-11-14
Filing date: 1976-11-02
Publication date: 1980-03-26
Also published as: NL7612613A; IT1071848B; FR2331437A1; JPS537777A; SU689603A3

Description

(54) IMPROVEMENTS IN OR RELATING TO TYRE CONSTRUCTION DRUMS (71) We, METZELER KAUTSCHUK AG, of Westendstrasse 131, 8000 Munchen 2, Germany, a body corporate organised under the laws of the Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement::- The invention relates to an axially and radially adjustable construction drum for pneumatic tyres, in which the drum comprises two base members at the drum ends, the relative distance between which is adjustable, in which the base members each support a respective set of ring segments whose external surfaces form a substantially cylindrical surface and which are radially adjustable by means of an inflatable bladder and on which is situated a resilient band with an inflatable member disposed therebelow for folding over the edges of plies, there being retained between the sets of ring segments a middle part of the drum which is extensible radially and in the longitudinal direction of the drum, and in synchronism with said inflatable members.

Tyre construction drums of this kind function as support members for tyre structures of the most diverse widths. Different tyre sizes can be produced on these drums without the need for interchanging. The axial adjustability is defined by the width of various parts of the drum. This width must not exceed a specific value, otherwise there will be a risk that the tyre material is pressed into the gaps in the course of stitching operations.

It is necessary, more particularly for small tyre manufacturing plants, to be able to use a tyre construction machine with a tyre construction drum which permits rapid but nevertheless exact resetting to different tyre dimensions. Tyre construction drums whose diameter can be correspondingly varied, are used to this end. It is, however, also desirable for the construction drum to be usable for different tyre or belt widths.

The German Gebrauchsmuster 1 896 294 discloses a construction drum in which the overall width is adjusted by the segments, which are radially movable on the base members, being also adjustable in the axial direction through slots and screw fasteners.

The space or annular gap produced between the two sets of segments is bridged by a spacer ring, a specific ring width being provided for each tyre dimension. Filling the annular gap by means of a spacer ring is important because only uniform, continuous working surfaces can be used for the construction of tyre carcases or of reinforcing inserts over the entire drum width. Larger gaps in the middle region cause the tyre carcase or the reinforcing belt to become deformed or partially pressed into the gap during the stitching operations. The width of the gap in the middle region of construction drums for the reinforcement inserts of belted tyres should not exceed 8 mm.

Width adjustment by means of the segments which are mounted in the slots is timeconsuming because each segment set contains many individual segments and each segment in turn is secured by means of two screw fasteners.

The German Patent Specification 1 729 664 also discloses a tyre construction drum in which width adjustment is performed by means of a spindle with screwthread portions of opposite sense and nuts which are traversable thereon and act on the base members. The middle region between the two segment sets in this embodiment is also bridged by an intermediate ring. The intermediate rings of different width comprise of fabric-reinforced rubber and are anchored on the segment sets by means of retractable pins. Beneath the resilient intermediate ring the gap is bridged by overlapping spring steel strips of arcuate shape. The additional steel strips are: necessary because the resilient intermediate ring alone is not able to absorb the stitching forces.

An intermediate ring of different width is also employed in this drum for each adjusted width. Insertion of the intermediate rings is time-consuming and labour-intensive. Until they engage, the intermediate rings must be expanded and pulled over the drums, the friction between rubber surfaces which slip upon each other being particularly adverse. The overlapping spring steel strips can also damage or possibly destroy the covering rubber band.

It is an object of the present invention to provide an axially and radially adjustable tyre construction drum of the kind described hereinbefore, the possible working axial width of which can be rapidly and reliably adjusted and expanded and which can be employed over a wide working range.

According to the invention, there is provided an axially and radially adjustable construction drum for pneumatic tyres, comprising two base members at the drum ends, the relative distance between which is adjustable, the base members each supporting a respective set of ring segments whose external surfaces form a substantially cylindrical surface and which are radially adjustable by means of an inflatable bladder and on which is situated a resilient band with an inflatable member disposed therebelow for folding over the edges of plies, there being retained betwen the sets of ring segments a middle part of the drum comprising a set of further segments spaced around the drum and and each comprising a plurality of longitudinally spaced plates slidable in the longitudinal direction of the drum on a respective guide which interconnects the sets of ring segments, each pair of longitudinally adjacent plates being interconnected by means of interposed resilient means.

Because of the compressive prestress, the inserted plates automatically space themselves uniformly during every adjustment in the axial width of the drum so that the procedure of adjusting the axial width of the drum can be performed in a short time without calling for manipulation in the middle region.

Conventional drum embodiments called for resetting times of between 3 and 6 hours but in the present arrangement the width can be adjusted within a few minutes.

To ensure that the distances between plates remain uniform during adjustment of the drum width so that the gaps between the plates are identical, each plate may have fixedly inserted therein two spring cartridges, each end of each of the spring cartridges being mounted in a centering bore of the respective leading plate and the other end projecting into a guide bore of the respective trailing plate, and in which the spring cartridges in each plate are diametrically offset around the guide bore with respect to the spring cartridges of the succeeding plate.

This step ensures reliable centering of the plates and the diametral offset enables spring cartridges to be inserted so that they simultaneously bias three plates in positive manner. To this end, the compressive prestresses of the spring cartridges must be sufficiently high to ensure that all plates are shifted during adjustment, even with the maximum drum width.

Preferably, each of the spring cartridges has a cup for receiving spring means and a lid retained against the cup by means of an adjustable abutment which is preferably rigid in the thrust direction of the spring means, the spring means being prestressed in compression between the cup and the lid.

To this end, the spring means may comprise serially connected plate springs, one or more coil springs inserted into each other or a rubber spring. It is most convenient and involves the least expenditure in terms of construction technique to use a kind of spring cartridge since more than 1000 of such spring cartridges must be used in a construction drum in which each of the sets of segments on the base members comprises, for example 26 segments.

The spring cartridges can be produced with a specific prestress or with a fixed longitudinal extension but it is also feasible for the prestress of the spring cartridge to be variable at will by means of an adjusting screw.

For reasons related to installation and in order to improve the positional stability of the plates between the segments, a respective intermediate plate may be inserted between each end plate of the middle part and the adjacent segments of the corresponding base member. Parts of the spring cartridges of the first and last plate of the middle part will then project into bores of the said intermediate plates.

Compressed air or vacuum is normally required in the region of the ring segments to actuate various drum elements. It will then be advantageous if the guides comprise pipes, both ends of which are supported in the segments and are adapted to conduct pressure medium or vacuum to the drum actuating elements. Additional pressure supply lines can then be omitted.

Preferably, outside the adjustable middle part, the edge regions of the tyre construction drum are provided with known peripheral bands which have ground hollowfillet indentations for accommodating a bead core. The peripheral bands are interchange able and the position of the ground hollowfillet indentations can be varied on the peripheral bands. The distance between both bead cores of a tyre structure can thus again be varied by the amount of the distances between the appropriate ground indentations in the peripheral bands. In the event of a dimension change which exceeds the adjustment width of the axially adjustable tyre construction drum, it is not necessary in each case for the entire drum to be exchanged; it would be sufficient to exchange the bands.This operation is much simpler and can be performed much more rapidly and the space for storing the additional drums can also be saved.

The invention will be further described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 shows a preferred axially adjustable tyre construction drum; Fig. 2 shows a tyre construction drum according to Fig. 1 with bands for construcing tyres with large distances between their beads; Fig. 3 shows a tyre construction drum according to Fig. 1 for constructing tyres with short distances between their beads; Fig. 4 shows another tyre construction drum according to Fig. 1 for constructing tyres with even shorter distances between their beads; Fig. 5 is a section through a middle part of the drum according to Fig. 1; Figs. 6 and 7 are sectional views taken on the lines I-I and II-II of Fig. 5 Figs. 8 and 9 show two embodiments of spring cartridges according to Fig. 5.

The tyre construction drum 1, shown partially in section in Fig. 1, has a substantially cylindrical surface. The tyre construction drum is retained by means of an internal tube 2 on a driving device which is not shown. Two base members 3 situated opposite each other are arranged on the internal tube 2 so as to be slidable along the longitudinal direction of the drum, each member surrounding a screwthreaded nut 4. The screwthreaded nuts 4 have screwthreading portions of opposite sense and are in engagement with complementary screwthreaded portions of opposite sense of a sleeve 5 which is rotatable but is axially fixed on the internal tube 2. The sleeve 5 is also provided wtih a gear rim 6 which meshes with a pinion 7 of a spindle 8. The spindle 8 extends through the base member 3 and bears axially on a peripheral collar 9 of the sleeve 5.A square section 10 is integrally formed on the end of the spindle 8 to enable the latter to be rotated.

A set of segments 12, which are radially slidable over guides 11 and are adjacently disposed in the circumferential direction of the drum 1 so as to form an approximately cylindrical working surface, is situated on each base member 3. The segments 12 are slidably by means of an inflatable bladder 13 to stop rings 14 (arrow 15). Air is supplied to the bladder 13, for example through a duct 16 which extends into a chamber 17 in the base member 3 to which the bladder 13 is connected.

To this end, the guides of the spindle 8 and of the base member 3 on the internal tube 2 are sealed by means of gaskets 18.

A respective inflatable member 19 for folding over the edges of plies, which member is covered by a resilient band 20 is situated on the top of each set of segments towards the edge of the drum 1. Near the inner edges of the segments 12 the band 20 has peripheral ribs 21 between which extend ports 22 which lead to the interior of the segments.

The said ports 22 are connected to pipes 23 which are biased with vacuum. Each of the pipes 23 is supported in blind holes 24 of two oppositely disposed segments 12.

The pipes are sealed with gaskets 47 and function as guides for the middle part 25 of the drum which bridges the distance between the sets of segments. The middle part 25 comprises segments 26 each of which is associated with two oppositely disposed segments 12.

Each segment 26 comprises individual plates 27. Spring cartridges 28, which overlap each other, are inserted under prestress between the said plates. Intermediate plates 29 are disposed between the segments 26 and the segments 12. The individual plates 27 are maintained at identical distances from each other by and with the spring cartridges.

Figs. 2 and 3 each show an axially and radially adjustable tyre construction drum according to Fig. 1 with peripheral bands 49 which have ground hollow-fillet indentations 51 in the edge regions 50 for engaging tyre beads. When buliding a tyre, the distances 48 between beads can be varied by interchanging the peripheral bands 49.

Fig. 4 shows a tyre construction drum 1 in which the distance 48 between beads is reduced, the ground hollow-fillet indentations 51 being situated at the axial middle of the peripheral bands 49 of the tyre construction drum.

The construction of the segments 26 is shown more clearly in Figs. 5. The crosssectional shape of the segments 26 corresponds to the outer region of the segments 12 (Figs. 6 and 7). Each segment 26 has twelve plates 27 which are guided on the associated tube 23 at identical distances 30.

The space between the plates 27 is maintained by the spring cartridges 28. Two spring cartridges 28 which are diametrally offset about a guide bore 31 are provided in each plate 27. Said spring cartridges comprise a cup 32 the edge flange 33 of which is pressed into a centring bore 52 of the appropriate plate 27, where appropriate by adhesive bonding, and whose rear end slides in a bore of the succeeding plates. At the front the spring cartridges 28 have lids 34 by means of which they are pressed into the preceding plate 27 or into the intermediate plate 29. A prestressed spring fills the free space 36 between the lid 34 and the cup 32. The prestress is obtained by means of a rigid stop abutment, for example an adjusting screw 35, which also guides the lid 34 with respect to the cup 32.

The arrangement of the spring cartridges 28 ensures proper centring of all the plates 27 and ensures that the segments 26 are correctly positioned on the associated tube 23 as the said segments 26 would otherwise rotate on the tube 23. It is of course also feasible to interpose a square-section guide or two guide elements between the segments 12 on which the position of the segments 26 would then be ensured without the aid of the spring cartridges 28. In this case it would be possible to incorporate simpler springs between the plates, the function of such springs being purely to maintain the distance between the individual plates 27.

Figs. 6 and 7 which are views of the first two plates 27 shown as a longitudinal section in Fig. 5 clearly show the diametral offset of the individual spring cartridges.

This is necessary to prevent the cartridges abutting against each other when the plates 27 bear completely upon each other (minimum drum width).

Centring sleeves 38 are inserted into the intermediate plate 29 to provide additional centring for the plates 27 and to function as an assembly aid, the said sleeves on the one hand engaging with the segments 12 and on the other hand with the plate 27 which is the first plate in each case.

Figs. 8 and 9 show embodiments of spring cartridges 28. The embodiment according to Fig. 8 contains serially connected plate springs 39 as the resilient element, the said plate springs being compressively prestressed by means of the adjusting screw 35 between the lid 34 and the cup 32. The compressive prestress is sufficiently large to ensure in each case that with the drum set to the maximum adjusting width there will still be sufficient spring force to ensure that the friction of the plates 27 on the tube 23 is overcome in the course of adjustment. The length 40 of the cup 32 is adapted so that the spring cartridges cannot abut against each other even if the plates bear completely upon each other.

The embodiment of the spring cartridge 28 according to Fig. 9 differs from that of the previously described embodiment The resilient element in this case is a rubber spring 41 which is accommodated between two cups 42 and 43 which are telescoped into each other, the length of the spring cartridge 28 being defined by noses 45 which slide in slots. The rubber spring 41 in this case is also prestressed in compression so that it is able to overcome the pull-out moment of the plates 27 even when the drum 1 is adjusted to its maximum width. To mount this embodiment of a spring cartridge, the cup 43 is provided with a peripheral flange 46 which conveniently comprises wall material associated with the cup 43 and deformed when the slots 44 are produced. The rubber spring 41 can be secured between the bottom of the cups 42 and 43.To ensure reliable functioning it would also be sufficient if the rubber spring is housed without being affixed between the cups.

Width adjustment of the drum 1 is initiated by rotation of the spindle 8. Advantageously, the spindle 8 is actuated by means of a withdrawable crank handle which is not shown and the end of the spindle is secured by a locking device to prevent unintentional rotation. As the pinion 7 rotates the sleeve 5 through the gear rim 6, the nuts 4 and therefore the two base members 3 move towards each other or away from each other, depending on the direction of rotation of the spindle 8. The tubes 23 slide in the blind holes 24. The spring cartridges 28 compel the plates 27 to spread axially automatically while maintaining a uniform mutual spacing between the segments 12.

In practice, a tyre construction drum of this kind has a width adjustment of approximately 40 mm. This means that the plates are situated at a distance of approximately 3 mm from each other with the drum set to the widest width. These distances are of no significance for any stitching operations in the middle region of the drum because the processed reinforcing fabric is not pressed into these narrow gaps.

In the narrowest position of the drum the plates 27 bear upon each other and present an integral, cylindrical working surface. The times required for adjustment, which used to be very long, can be reduced to a few minutes with the previously described setting because of the elimination of the need for exchanging any intermediate rings or spacer rings. Initial installation of the segments 26 can be simplified by prefabrication with the spring cartridges 28 and by packaging to their narrowest widths by means of tensioning bands. They are then slid on to the guides between the segments 12, the tensioning bands are then released, after which each segment automatically fills the space.

Suitably modified segments can of course also be employed for other drums intended for the construction of tyre components.

They need merely be adapted to the appro priate conditions and must be provided with suitably modified spring cartridges for longer operating distances or shorter or wider gaps.

WHAT WE CLAIM IS: 1. An axially and radially adjustable construction drum for pneumatic tyres, comprising two base members at the drum ends, the relative distance between which is adjustable, the base members each supporting a respective set of ring segments whose external surfaces form a substantially cylindrical surface and which are radially adjustable by means of an inflatable bladder and on which is situated a resilient band wtih an inflatable member disposed therebelow for folding over the edges of plies, there being retained between the sets of ring segments a middle part of the drum comprising a set of further segments spaced around the drum and each comprising a plurality of longitudinally spaced plates slidable in the longitudinal direction of the drum on a respective guide which interconnects the sets of ring segments, each pair of longitudinally adjacent plates being interconnected by means of interposed resilient means.

2. A tyre construction drum as claimed in claim 1, in which the distances between the longitudinally adjacent pairs of plates are of equal width, the resilient means comprising spring cartridges.

3. A tyre construction drum as claimed in claim 2, in which each plate has fixedly inserted therein two spring cartridges, each end of each of the spring cartridges being mounted in a centering bore of the respective leading plate and the other end projecting into a guide bore of the respective trailing plate, and in which the spring cartridges in each plate are diametrically offset around the guide bore with respect to the spring cartridges of the succeeding plate.

4. A tyre construction drum as claimed in claim 2 or 3, in which each of the spring cartridges has a cup for receiving spring means and a lid retained against the cup by means of an adjustable abutment which is preferably rigid in the thrust direction of the spring means, the spring means being prestressed in compression between the cup and the lid.

5. A tyre construction drum as claimed in claim 4, in which the spring means comprises serially connected plate springs, spiral springs, or a rubber spring.

6. A tyre construction drum as claimed in any one of the preceding claims, in which a respective intermediate plate is inserted between each end plate of the middle part and the adjacent segments of the corresponding base member.

7. A tyre construction drum as claimed in any one of the preceding claims, in which the guides comprise pipes, both ends of which are supported in the segments and are adapted to conduct pressure medium or vacuum to the drum actuating elements.

8. A tyre construction drum as claimed in any one of the preceding claims, in which the width adjusting device contains a sleeve which is rotatable on an internal tube and which has two portions of external screwthreading of opposite sense, each engaging with a nut of the base members, a spindle being axially supported on the sleeve and meshing with a pinion, a gear rim being provided on the sleeve, and being guided with respect to the exterior by means of one of the base members.

9. A tyre construction drum as claimed in any one of the preceding claims, in which, outside the adjustable middle part, the edge regions of the tyre construction drum are provided with known peripheral bands which have ground hollow-fillet indentations for accommodating a bead core.

10. A tyre construction drum as claimed in claim 9, in which the position of the ground hollow-fillet indentations can be varied on the peripheral bands.

11. A tyre construction drum as claimed in claim 9 or 10, in which the peripheral bands are interchangeable.

12. An axially and radially adjustable drum for constructing pneumatic tyres, substantially as hereinbefore described with reference to Figures 1, 2, and 5 to 8 of the accompanying drawings.

13. An axially and radially adjustable drum for constructing pneumatic tyres substantially as hereinbefore described with reference to Figures 1, 2, 5 to 7, and 9 of the accompanying drawings.

14. An axially and radially adjustable drum for constructing pneumatic tyres substantially as hereinbefore described with reference to Figures 1, 3, and 5 to 8 of the accompanying drawings.

15. An axially and radially adjustable drum for constructing pneumatic tyres substantially as hereinbefore described with reference to Figures 1, 3, 5 to 7, and 9 of the accompanying drawings.

16. An axially and radially adjustable drum for constructing pneumatic tyres substantially as hereinbefore described with reference to Figures 1, and 4 to 8 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. priate conditions and must be provided with suitably modified spring cartridges for longer operating distances or shorter or wider gaps. WHAT WE CLAIM IS:

1. An axially and radially adjustable construction drum for pneumatic tyres, comprising two base members at the drum ends, the relative distance between which is adjustable, the base members each supporting a respective set of ring segments whose external surfaces form a substantially cylindrical surface and which are radially adjustable by means of an inflatable bladder and on which is situated a resilient band wtih an inflatable member disposed therebelow for folding over the edges of plies, there being retained between the sets of ring segments a middle part of the drum comprising a set of further segments spaced around the drum and each comprising a plurality of longitudinally spaced plates slidable in the longitudinal direction of the drum on a respective guide which interconnects the sets of ring segments, each pair of longitudinally adjacent plates being interconnected by means of interposed resilient means.

17. An axially and radially adjustable

drum for constructing pneumatic tyres substantially as hereinbefore described with reference to Figures 1, 4 to 7, and 9 of the accompanying drawings.